摘要:

ExtractA modification of a previous method for the assay of γ glutamyl transpeptidase (GGTP) was developed. Substrate solubility difficulties alluded to by other investigators were avoided by employing heating and solubilization of the chromogenic substrate γ glutamyl-β-naphthylamide in a medium of carbonate 0.05 M and Tris buffer 0.1 M at pH 9.5. The kinetics and conditions for such an assay are described. Whole intestinal homogenates of adult male guinea pigs were used as the source of the enzyme.The developmental pattern of this enzyme was determined in fetuses at 55 and 63 days of gestation and at varying times from 1 to 90 days of age. A total of 69 animals was assayed. The general pattern was that of high specific activity during prenatal life, with a rapid decline during the neonatal period (3–24 days of age) and a slight increase after 55 days of age.Other guinea pig organs were studied. Liver and kidney were found to contain enzyme activity greater than that of the intestine. Subcellular fractionation of intestinal mucosa using ultracentrifugation revealed a twenty-fold enrichment of activity in jejunal brush border membrane, compared with whole jejunal homogenates when expressed as specific enzyme activity per mg of protein. The stability characteristics of GGTP disclosed no loss of specific activity when stored at −28° for 50 days.This simple enzyme assay, stability of the enzyme when frozen, subcellular distribution in the intestinal brush border membrane, and an unusual developmental pattern made this enzyme a useful adjunct to the study of intestinal protein metabolism.SpeculationThe unique ability of GGTP to hydrolyze > glutamic acid-peptide bonds and the location of the enzyme in the intestinal brush border suggest a role for this enzyme in the metabolism of an unusual group of physiologically important peptides such as glutathione, folic acid, and gluten-gliadin. The significance of these γ-bonded compounds may now be approached in order to investigate the role of this enzyme in gluten enteropathy and related disorders.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractPlasminogen-activator activity was measured in lungs from 7 newborn premature infants examined at autopsy (control lungs) and 11 infants dying of hyaline membrane disease (hyaline membrane lungs) and was reevaluated by using human and rabbit fibrin substrates in addition to the traditional bovine fibrin substrate. The whole homogenate and the supernatant and sediment fractions from the lungs of the normal infants were active when tested on unheated human, bovine, and rabbit fibrin plates. In comparison, 10 of the 11 specimens of hyaline membrane lungs failed to lyse either bovine or human fibrin when the whole homogenate or the supernatant or sediment fractions were tested. Rabbit fibrin substrate was digested by all the hyaline membrane lung homogenates, but only after a prolonged incubation period. Mixtures of the supernatant fraction from any of the 10 hyaline membrane specimens, plus equal volumes of lung homogenate from a normal infant, resulted in total inhibition of normal plasminogen-activator activity.Mixture of 0.05 ml 2M KSGN with 0.1 ml normal lung homogenate enhanced plasminogen-activator activity by approximately 80% using human, bovine, or rabbit fibrin substrates. The addition of thiocyanate also induced plasminogen-activator activity of homogenates from 11 hyaline-membrane lungs. Three of these 11 specimens caused lysis of heated human fibrin plates in the presence of thiocyanate, indicating direct protease activity.Extraction of the hyaline-membrane lungs with thiocyanate by the method of ASTRUP and Albreghtsen[5]revealed plasminogen-activator activity in all specimens. None of the thiocyanate extracts caused lysis of heated fibrin plates. Thus, the direct proteolytic activity, induced in some lung homogenates by the addition of thiocyanate, did not survive the acid precipitation phase of the thiocyanate extraction procedure.Saline extracts (supernatants) of 11 hyaline membrane and 7 control lungs were tested on unheated and heated human fibrin plates with the addition of either 2M KSGN or water to determine whether thiocyanate enhanced activator activity by increasing the solubility of the enzyme or by direct enhancement of enzyme activity. Activator activity of the supernatant fractions from 7 control lungs was enhanced by the addition of 2M KSCN; three of the 7 specimens showed a low degree of protease activity on heated plates. The enhancement of soluble enzyme activity in the controls indicated a direct effect of the electrolyte on enzyme activity. Hyaline membrane lungs, however, failed to develop plasminogen-activator activity in 8 of 11 supernatant fractions, and 2 of the 3 specimens that did develop lytic activity also lysed heated fibrin. It appeared, therefore, that the majority of hyaline-membrane lungs lacked saline-soluble plasminogen activator in contrast to control lungs. Acid precipitates prepared from the inactive saline extracts of hyaline membrane lungs and dissolved

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractLiver biopsies from two children with Morquio's disease were studied by electron microscopy. The diagnosis was based upon typical clinical findings and x-ray examination. Urinary excretion of keratosulfate was abnormally high in both cases. The Kupffer cells contained large relatively electron-lucid inclusions (0.3 to 4.3 μU in diameter) bounded by a single membrane and containing a finely arranged protein-like precipitate. These inclusions occasionally appeared as compact bodies (figs. 2 and 3). Membranous 'myelin-like' round bodies were infrequently seen in the vacuoles. Hepatocytes were usually normal, but some contained a few electron-lucid inclusions that resembled those seen in the Kupffer cells, although they were smaller in size (0.4 to 1.9 μU) (fig. 5). Peribiliary dense bodies were numerous and rarely contained myelin-like figures (fig. 4). In some atypical groups of cells, discontinuous limiting membranes were observed. These cells also contained electron-lucid vacuoles bounded by single membranes of varying sizes (0.3 to 4.0 μU) (fig. 6).The inclusions were very similar to those previously described in different forms of gargoylism, although the site was different. The rupture of some Kupffer and/or parenchymal cell membranes, secondary to technical manipulations, apparently caused the peculiar aspect of the atypical groups of cells.SpeculationThis study supplies new evidence linking Morquio's disease and gargoylism. Some pathogenic mechanisms appear to be similar in these diseases, both of which affect mucopolysaccharides of the liver in a similar way.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractAt 15 days after birth, the small intestine of the rat showed a striking increase in relative weight, an increased depth of intestinal crypts, an elevation of the mitotic and the labeling index of crypt cells, and a decrease in the ratio of height of the villi to depth of the crypts.Metabolically, the biological half-life of14C phenylalanine incorporated into protein was decreased in the intestine of 21-day-old rats compared with that of the 32-day-old rat. With autoradiography, a decreased half-life of3H-leucine in crypt cells was noted in rats 5 and 21 days of age, compared with fully weaned rats 32 days of age. These observations indicated that protein turnover is not completely dependent on cellular turnover in suckling rats.Artificial feeding of suckling rats from 9 to 15 days of age produced an increase in the relative weight, mitotic index, depth of crypts, and activity of invertase in the jejunum. Prolonged administration of hydrocortisone to newborn rats resulted in similar changes in the duodenum and in the jejunum, but not in the ileum. These changes could be related to an increased rate of cellular migration along the villi of the duodenum and the jejunum. It was concluded that both diet and hormones were important factors in the marked changes in intestinal cell proliferation and differentiation observed at weaning.SpeculationThe usual changes in cellular proliferation and differentiation of the intestinal mucosa of the weanling rat and the observation that these changes can be stimulated precociously suggest that the intestinal tract of suckling rats could be used to investigate further those factors important to the control of cell differentiation. Since cell turnover increases to adult levels after 15 days of age, the observed increase in protein turnover in suckling and in weanling rats, compared with that of adult rats, suggests that at these ages protein turnover is not coordinated with cell turnover.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractA nine-month-old male with recurrent pulmonary and gastrointestinal infections and persistent lymphopenia was presumed to have hereditary thymic dysplasia. He was unresponsive to intradermal injections of Monilia antigen, Varidase®, and diphtheria toxoid, and could not be sensitized to dinitro fluorbenzene. He failed to reject a skin allograft. Peripheral blood lymphocytes were unresponsive to phytohemagglutinin stimulation. The serum contained markedly diminished concentrations of γA, γM, and γG globulins, and he could not form specific antibodies to a variety of injected antigens.A female sibling of the child was presumed to have leukocytes that shared the major histocompatibility antigens with the leukocytes of her brother. Consequently, 100 × 106bone marrow cells were transplanted from the sister into the affected infant. Five days later, what appeared to be a graft-versus-host reaction was noted with hepatosplenomegaly, a maculopapular rash, edema, diarrhea, and, terminally, profuse hemorrhage. At autopsy the presumptive diagnosis was confirmed: a rudimentary thymus gland weighing 1.5 g was found. Lymph nodes and spleen lacked lymphoid follicles. Plasmacytoid cells, presumably of donor origin, were found in great abundance in the spleen, blood, and bone marrow.SpeculationFurther attempts to reconstitute immunocompetence in infants with thymic dysplasia should be pursued with transplants of histocompatible tissues. The limitations of current methodology in assessing minor differences in histocompatibility suggest, however, that immunosuppressive therapy is required to prevent the lethal effects of seemingly histocompatible cells from an immunocompetent donor in an immunologically unresponsive host. Ideally, such transplants should be performed only when a donor identical with the recipient at the HL-A locus is available.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractThe calorigenic effect of an artificial formula, Adapta, was examined in premature infants kept at and below the neutral temperature. After a preliminary period of 15–30 minutes, a feeding (40–60 ml) was offered or given by gavage. The test feeding was followed by an experimental period of four hours, during which time oxygen consumption and CO2production were continuously recorded by an open circuit method using the Kipp diaferometer.The results of investigations carried out in the zone of thermoneutrality are summarized in table I. The amount of oxygen consumed 30 minutes after ingestion of the formula was already appreciably larger than that corresponding to the basal metabolic rate. At 90 or 120 minutes, the average oxygen consumption was 30% higher than that at the preliminary level. Oxygen consumption then fell and had approached the fasting level by the end of the period of observation.In order to obtain the cumulative effect of thermogenesis, total and basal heat production were calculated for a period of four hours. The average amount of total extra calories was 1.7 kcal/kg which, in relation to basal heat production during the same period of time and to the ingested calories, represented an increase of 26.4 and 9.2%, respectively (table VI).The changes in oxygen consumption at different levels of thermoregulatory heat production in totally and partially swaddled premature infants maintained at 20–22° are shown in tables II, III and IV. The responses are also diagrammatically compared (fig. 4). It can be seen that the magnitude of specific dynamic action is the same for babies in a thermoneutral and colder environment, despite the difference in the preingestion levels of oxygen consumption. Control experiments in nonfed premature infants revealed that the specific dynamic action of food in a heat-losing environment is not due to muscular activity, but appears in an additive manner and independently of the metabolic increase induced by the cold environment (table V).The summation of the metabolic response to cold and to food was also reflected by the behavior of body temperature. The ingestion of 50 ml of formula stopped the fall in body temperature and even caused a small transient rise during the period of maximum increase in heat production.SpeculationWhen considering the various factors upon which the zone of thermoneutrality depends, it is likely that a protein or calorie-rich feeding may constitute a significant thermal burden to premature infants cared for at neutral temperature. In contrast to thermoneutral conditions, however, the independence of the stimulating effect of food and cold on thermogenesis indicates that specific dynamic action below the critical temperature can be regarded as a useful source of heat to help maintain the body temperature in a heat-losing environment. Future studies are needed to clarify the thermoregulatory significance of postprandial thermogenesis in premature infants cared for under various environmental conditions and maintained on different feeding regimens.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractDuring normal growth in male rats (3 weeks to 3 months of age) weighing from 50–400 g, kidney weight and glomerular filtration rate (GFR) increased at slower rates than did body weight; in contrast, the rate of increase in kidney weight and glomerular filtration rate were the same, and the ratio of GFR:g kidney weight was constant after 4–5 weeks of age. The ratio of maximal glucose reabsorption (TmG) to GFR increased only slightly with growth. Na-K-dependent ATPase activity/mg light microsomal protein from kidney cortex and QO2did not change during growth. Kidney growth up to 200 g body weight at 16 weeks of age was due more to an increase in cell number; beyond then it was due more to an increase in cell size. The pattern of function-structure relation during growth differed from that observed in kidney hypertrophy secondary to uninephrectomy. It was not specifically determined from cell number or size but from some property proportional to total protein mass or to the product of cell number and cell mass.SpeculationTubular functions of the nephron during growth increase in proportion to each other and in proportion to total renal mass. This pattern of increase differs in several respects from that which occurs following uninephrectomy. The inference is that growth response differs in fundamental biological character from the hypertrophy response.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractIntrauterine exchange transfusions were conducted in fetal sheep using adult sheep as donors. Indwelling catheters in the fetus permitted sampling of blood for 8 to 36 days following the transfusion. In the first days after the procedure there was a decreased oxygen affinity of umbilical blood, an increase of about 5 mm Hg in umbilical venous O2tension, and a decrease of about 30% in O2saturation. In the following weeks there was a gradual return of O2affinity, PO2, and oxygen saturation to normal. In all of the experiments there was a good correlation between the O2affinity of umbilical blood and the percentage of adult cells present. This correlation indicated that adult cells retained a normal O2dissociation curve even after weeks of exposure to the new environment. Despite an increased umbilical venous PO2, the fetal reticulocyte count increased significantly after transfusion, but the oxygen capacity of umbilical blood remained within normal limits.SpeculationThese studies suggest that the correction of fetal anemia in erythroblastosis fetalis by the use of fetal blood instead of adult blood would produce a greater increase in the amount of hemoglobin capable of carrying oxygen at the low oxygen tensions characteristic of the fetal circulation.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractFollowing weaning, Sprague Dawley rats were given 60% of a normal Purina chow intake until 7 weeks of age. There was a reduced DNA content in the cerebrum at 49 days of age. Previous failure to demonstrate reduced DNA content in rat brain during undernutrition could relate to preoccupation with whole brain analysis. The present study indicates that cerebral DNA increases in normal rats after weaning.The cell size or the ratio of protein: DNA increased in the muscle tissues of rats subjected to the caloric restriction, while the ratio of RNA: DNA increased in all tissues studied. These findings are contrary to those found in protein deficiencyper se.Carcass weight, fat, and water were below expected levels, but skeletal collagen was less affected.Rats from 26 to 38 days of age, given an increased insulin-induced caloric intake, showed an excess weight gain per gram of food consumed per day and an excess growth of muscle and fat. In contrast, cerebral weight, water, protein, DNA, and RNA content were reduced possibly because of periodic hypoglycemia.SpeculationFollowing weaning, rats subjected to sustained caloric restriction have reduced cell numbers for age and are said not to reach expected cell populations on rehabilitation. With caloric restriction, growth hormone may no longer be effective at the cellular level, but insulin activity continues. Although the ratio of cytoplasm: nucleus is maintained, DNA replication is minimal. Alternatively, since DNA content in the cerebrum decreases, hypothalamic or acidophilic cells may be lost, and growth hormone production may be insufficient for adequate DNA replication and somatic growth.When protein is restricted, the failure of cells to increase in size may be associated with atrophy of the pancreas and a decrease in insulin production.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

ExtractThis study explores changes in deoxyribonucleic acid (DNA), ribonucleic acid (RNA), protein, and water content of muscle, liver, and cerebrum in hypophysectomized rats and the effects of injecting growth hormone, insulin, or growth hormone with epinephrine conjointly over an eleven-day period.Male hypophysectomized rats, 26 to 49 days of age, fed anad libitumdiet were studied. At 38 days of age they were injected with insulin, 0.4 to 1.8 units per day, with bovine growth hormone (250 μUg/day) or with the same amount of growth hormone and epinephrine, 5 to 20 μUg/day, concomitantly, or were untreated until the 49th day of age. Control rats of the same age were either pair-fed to untreated hypophysectomized rats or given anad libitumdiet.Untreated hypophysectomized rats showed poor body weight gain per unit food intake and reduced skeletal growth. The nucleic acid and protein content of liver, muscle, and cerebrum was reduced when compared with controls of the same age. The ratio of protein: DNA (cell size) was increased for body size but reduced for age.Administration of insulin caused hypertrophy of liver cells and increased the protein content of liver, but did not affect muscle and cerebrum. DNA content of liver or cerebrum did not increase, and the gain in DNA content of muscle was not remarkable. There was a definite increase in RNA content of muscle, liver, and cerebrum and in the ratios of RNA: DNA and protein: DNA of liver.Injections of growth hormone caused an increase in DNA (cell number), RNA, and protein content in liver, muscle, and cerebrum. There was a reduction in the ratio of cytoplasm to nucleus. The protein increment was nullified by the injection of epinephrine in conjunction with growth hormone. DNA content of muscle and liver was increased, but not to the level produced by growth hormone alone. The increase in RNA content of liver, muscle, and cerebrum was again significant; the ratio of RNA: DNA increased only in liver. Caloric intake of untreated hypophysectomized rats and those treated with growth hormone or insulin was comparable. Rats injected with epinephrine showed a significant increase in caloric intake.The results indicate that insulin is involved with growth in cell size, while growth hormone is active with respect to the increase in cell number. Both hormones are required for optimal growth.SpeculationThe present study indicates that both growth hormone and insulin are required for optimum cell growth. Epinephrine administration retards the increase in cell number that normally occurs in hypophysectomized rats receiving growth hormone. This suggests that overactivity of the sympathetic pathways may retard growth and produce effects that simulate hypopituitarism.

ISSN:0031-3998    

出版商:OVID    

年代:1969

数据来源: OVID