摘要:

Pediatric renal allograft recipients receive a relatively greater increase in renal mass than do adult recipients because the donors are usually adults. They also have a higher frequency of posttransplant hypertension and cardiovascular problems. Avoiding other variables common to both pediatric and adult patients including pre-existing hypertension and renal disease and the use of corticosteroids, renal mass was increased by up to 50% in immature dogs by implanting large kidneys from adult dogs. Cardiovascular and renal function were studied before and after transplantation. Blood pressure was decreased in anesthetized mongrel pups at 2 hr and 3 days after surgery by 22 and 6 mm Hg, respectively; pressure was similarly reduced in conscious, chronically catheterized DLA-matched beagle pups maintained for 14 days, from 96.1 ± 3.0 to 76.8 ± 6.7 mm Hg (P< 0.001). Glomerular filtration rate was decreased at 2 hr and 3 days, but was normal at 14 days. Cardiac output was reduced in four of five recipients at 2 hr but was unchanged at 3 days. Plasma volume was increased at 3 days in the mongrel dogs but was normal in the beagles both at 2 and 14 days. We conclude that an increase in renal mass of up to 50% by itself does not cause hypertension in the dog and that other factors may be implicated in pediatric allograft recipients.SpeculationSince increase in renal massper sedoes not cause hypertension in healthy immature pups, other factors may be responsible for posttransplant hypertension in pediatric renal allograft recipients. Likely candidates are pre-existing renal disease, pre-existing vascular disease, and the use of corticosteroids. Immature animals may respond differently than do adults to stimuli which contribute to posttransplant hypertension.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

An oyster gill ciliostatic factor material has been isolated from the saliva of patients with cystic fibrosis (CF) by utilizing its ability to bind to α-amylase. It was quantitatively assayed by its ability to reversibly inhibit rabbit muscle glycogen debranching enzyme. The specificity of this CF factor material was investigated by comparing activities from the saliva of CF homozygotes (patients) varying in age, sex, and the severity of the disease; CF obligate heterozygotes (carriers); normal control subjects who had no family history of CF; non-CF asthmatic and allergic bronchitis patients; non-CF immunologically deficient patients with chronic respiratory problems; non-CF juvenile diabetic patients; non-CF pancreatic insufficiency patients; non-CF patients with obstructive liver cirrhosis; and non-CF patients with ectodermal dysplasia. The results show that the CF factor material isolated from CF saliva is specific to subjects with cystic fibrosis and is not associated with similar non-CF chronic disease states, nor is it produced as a result of an organ pathology associated with CF. There was no correlation between the amount of factor present in an individual CF homozygote sample and the severity of the disease. In the case of both the CF homozygote and heterozygote samples, there was also no correlation in either age or sex and the amount of factor present. The degree of inhibition produced by CF homozygotes compared to CF heterozygotes is characteristic of the autosomal recessive mode of inheritance of CF. This finding appears to associate the isolated CF factor material with the affected CF gene and suggests that the factor material is related in some way to the genetic lesion in CF.SpeculationThese studies indicate that the salivary cystic fibrosis factor material isolated by the glycogen-complex method is in some way dependent on the cystic fibrosis gene and is not associated with similar non-cystic fibrosis chronic disease states or produced as a result of the pathologic alterations in those organs commonly affected in cystic fibrosis.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Pregnant dogs were starved for 72 hr while controls were fasted overnight. Maternal starvation significantly reduced fetal birth weight (269 ± 7.2versus294 ± 4.4 g). Total caloric deprivation had no effect on maternal or fetal blood glucose concentrations at the time of delivery; however, fasting neonatal blood glucose levels were depressed during the first 9 hr of life. Starvation produced a large elevation of maternal free fatty acids (1.68 ± 0.39versus0.74 ± 0.2 mM) and ketone bodies (2.99 ± 0.70versus1.04 ± 0.48). Although fetal free fatty acids increased minimally (0.39 ± 0.03versus0.22 ± 0.07), ketone body levels were markedly elevated (2.53 ± 0.35versus1.01 ± 0.32). After birth, plasma-free fatty acid and β-hydroxybutyrate levels were lower in pups of starved mothers at 3 hr, and acetoacetate was lower at 6 and 9 hr. Other alternate fuels such as amino acids demonstrated lower levels of glutamine in pups of starved mothers throughout the day (except 3 hr), whereas alanine levels declined significantly only at 24 hr (114.9 ± 15versus187.6 ± 26 μM.Glucose production was significantly depressed in pups of starved mothers at 3 (13.7 ± 1.4versus22.7 ± 3) and 9 hr (17.5 ± 2.2versus26.0 ± 2.8 μmoles/kg/min), whereas glucose clearance rates were elevated at 3, 6, and 9 hr of age. Lactate carbon incorporation into glucose increased throughout the day but was not significantly affected by prior maternal starvation.SpeculationBecause glucose concentration and turnover were depressed whereas glucose clearance was elevated early during neonatal fasting, diminished oxidation of alternate fuels (such as fatty acids) may necessitate enhanced glucose consumption. Diminished intrahepatic oxidation of fatty acids may limit the energy source for sufficient glucose production from gluconeogenic precursors.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Recent studies have demonstrated the ability of visible light or phototherapy to modify the intracellular DNA of prokaryotic and eukaryotic cells. The present study was undertaken to determine the effect of light used in phototherapy on antibiotic resistance in prokaryotic cells using tester strains of gentamicin-sensitiveEscherichia coliandStaphylococcus aureus.A growing population of the tester microorganisms was inoculated on plates containing nutrient medium and gentamicin. Experiments were performed to determine the effect of blue light on the induction of gentamicin-resistant mutants. The plates were divided into two populations, one of which was illuminated, while the other was kept in the dark to serve as a control. During photoirradiation, the plates were protected from direct sunlight and air cooled to maintain a temperature of 27°C. The sample distance from the light source was adjusted to maintain a fluence rate (450 nm) of 141 uW/cm2. Control experiments were performed to investigate the effect of photoirradiation on the media and gentamicin. An increased frequency of mutation to gentamicin resistance was seen in the irradiated population of bacteria. The mutagenic effect was observed over a wide range of gentamicin concentrations and correlated in a linear fashion with increasing duration of photoirradiation. There was an inverse correlation between the size of the bacterial inoculum and the recovery of mutant bacteria.SpeculationIn view of the demonstrated ability of high-intensity visible light to modify intracellular DNA and induce mutations in bacterial populations, the relationship between the widespread use of phototherapy and the emergence of multiple antibiotic-resistant bacteria in nursery populations needs to be determined.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Previous studies have demonstrated that phototherapy depresses serum riboflavin in jaundiced infants. The potential long-term hazards of thisin vivoreaction may be significant in view of thein vitroreaction of riboflavin which modifies intracellular DNA in eukaryotic and prokaryotic cells. Previous investigations have suggested that the DNA-modifying activity of riboflavin results from the generation of singlet oxygen and photooxidation of the guanine moieties of the DNA. In the present study, we demonstrate that singlet oxygen is not involved in the photodynamic reaction of riboflavin and deoxyguanosine.SpeculationIn view of the known relationship between DNA-modifying activity and mutagenesis and carcinogenesis, the photodynamic reaction between riboflavin and deoxyguanosine may have adverse long-term effects on children exposed to phototherapy. A better understanding of the characteristics of this photochemical reaction may permit the development of a phototherapy unit effective in the photoisomerization of bilirubin yet devoid of DNA-modifying activity.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

HLA identical fibroblasts were transplanted into three patients with Sanfilippo A syndrome in an attempt to prolong the effectiveness of enzyme replacement therapy. The donors were the patients' mothers or brother and showed no mixed leucocyte reaction when tested against their recipients' cells. Fibroblast cultures from donors were established with 0.2 x 0.3 cm full-thickness skin biopsies from the anterior surface of the forearm; and their ability to correct abnormal35SO4incorporation in the recipients' cells was confirmed before grafting. At the time of grafting, all patients were severely mentally subnormal. All three patients were on an immunosuppressive regimen of 25 mg Imuran and 20 to 25 mg prednisolone daily for 4 wk before fibroblast transplant, and this was continued for approximately 5 months afterwards. When the primary cultures were confluent, the cells were removed by trypsinisation, and approximately 2 x 108viable cells were injected as a suspension into four subcutaneous dorsal sites.Excretion of urinary glycosaminoglycans precipitable by 5-aminoacridine increased markedly in all three patients after transplant, the mean increases ranging from 12 to 76%. Uronic acid-containing low-molecular-weight oligosaccharides in the urine also increased considerably in two of the three patients, with mean increases of 3, 65, and 84% being recorded. Oligosaccharides were separated into six fractions (I-Va) by chromatography on Bio-Gel P-2. Urine samples collected before transplant contained a much higher proportion of oligosaccharides of larger hydrodynamic size than did samples taken after treatment. The relative proportions of peaks II-V decreased after transplant, whereas at the same time, there was marked increase in the proportion of peak Va. The sulphamino/hexosamine molar ratios of fraction IV decreased from 0.64 to 0.29 and from 0.53 to 0.35 in two of the three patients after transplant, whereas the third patient showed little change. A protein fraction precipitated by ammonium sulphate from urine samples was tested for its ability to reduce the abnormally high35SO4accumulation in fibroblasts cultivated from biopsies taken from each patient before transplant. Most samples taken before transplant had little corrective factor activity, with mean activities ranging from 2.5 to 19% of normal control values. Excretion of corrective factor rose sharply after transplant in all three patients, with a mean level ranging from 48 to 58% of that found in normal age-related controls. The three patients selected for this treatment were observed for periods ranging from 3 years, 3 months to 2 years, 2 months, during which time there were no consistent changes in development achievements, joint mobility, or liver and spleen size as assessed by serial scans.SpeculationWe speculate that the implanted donor fibroblasts survived for a long period of time and possibly even increased in number in the recipients' subcutaneous space. They released glucosamineN-sulphatase, which could enter the patients' cells by adsorptive endocytosis and become incorporated into lysosomes, increasing catabolism of glycosaminoglycan accumulated there. It is possible that repeated fibroblast transplants may increase enzyme levels sufficiently to produce clinical correction, particularly in younger patients in whom physical and mental deterioration has not yet become irreversible.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

This study determined the relation between hematocrit and resistivity of fetal blood and compared it with values obtained in similar studies on adult blood. Both exponential and Maxwell-Frick-estimated relationships were calculated and compared. The results indicate that there is no significant difference between resistivity in adult and fetal blood. The best relation between blood resistivity and fetal hematocrit is obtained by using the Maxwell-Frick estimated curve calculated in the following manner:ρ = 53.0(1 + χ · h)/(1 - h)whereχ = 1.2h = H/100 (H = hematocrit).SpeculationHematocrit varies over a wide range during the newborn period. Accurate knowledge of resistivity-hematocrit relationships over the entire hematocrit range is essential whenever blood resistivities are to be estimated from hematocrit values. This study reveals that a better correlation is obtained when using the Maxwell-Frick model instead of the ordinary exponential model. Thus, a tool is offered to improve the accuracy of the impedance cardiography method in newborns.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Twelve newborn lambs less than 48 hr old had their high oxygen affinity blood exchanged for low-affinity fresh adult blood. Tissue oxygenation, hemodynamic status, blood gases, and myocardial function were compared before and after the exchange transfusion. The P50was increased from 18 to 29 mm Hg after exchange transfusion; pH and hemoglobin levels remained constant; and there was no change in myocardial function, arteriovenous O2content difference, O2consumption, or cardiac output. However, mixed venous Po2was significantly increased with low affinity red cells (33versus23 mm Hg).SpeculationThis study suggests that in the immediate neonatal period adequate a lowering of red cell oxygen affinity under normoxemic conditions can result in a increase in tissue Po2.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

Blood from full-term newborns was compared to adult blood for its ability to regenerate prostaglandin I2(PGI2)-like activity from vascular tissue. The neonate possesses a markedly decreased ability to regenerate PGI2(0.10 ± 0.07 ng/mg vascular tissue) when compared to the adult (0.42 ± 0.12). This decreased activity was not due to the presence of an inhibitor in neonatal blood. The impaired ability of neonatal blood to regenerate PGI2-like activity was related to its markedly decreased antioxidant potential and was corrected (0.34 ± 0.08 ng/mg vascular tissue) by the addition of Vitamin Ein vitro.Plasma PGI2-like regenerating activity had normalized by 3 to 5 months of age (0.41 ± 0.11 ng/mg).SpeculationThe neonate demonstrates a normal bleeding time despite concomitant impairment in platelet function. Our finding of a deficiency of plasma prostaglandin I2(PGI2)-like regenerating activity may provide an explanation for the paradoxical normal neonatal bleeding time. Plasma PGI2-like regenerating activity normalized by 3 to 5 months of age, at a time when platelet function also is no longer impaired. The physiologic impairment in platelet function observed in the neonate is thus a teleologic necessity, providing a compensatory safety mechanism to counteract the prothrombotic tendency induced by a deficiency of plasma PGI2-like regenerating activity.

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1981

数据来源: OVID