摘要:

ExtractStudies of platelet function were performed on venous blood specimens from 64 newborn infants within 0–48 h after birth. Fifty-two of the infants studied were normal, full-term average for gesta-tional age (AGA) infants, three were normal, premature AGA infants, seven were premature AGA infants with the respiratory distress syndrome (RDS), and two were premature AGA infants who had repeated apneic periods. Although it was not possible to study all variables of platelet function in each of the groups, those studies that were performed showed no differences in the results based on the group to which an individual infant belonged.Compared with 24 normal adult controls, the infants showed impaired platelet aggregation in the presence of ADP, collagen, and thrombin. The mean time required for maximal platelet aggregation with ADP, collagen, and thrombin for the adults was 120, 230, and 74 sec, respectively, compared with values of 160, 443, and 158 sec for the infants (table II, figs. 2, 3, and 4). The percentage total platelet aggregation with ADP, collagen, and thrombin for the adults was 79, 91, and 74% compared with 47, 73, and 47%, respectively, for the infants (table II, figs. 2, 3, and 4). Infant whole blood and platelet-rich plasma clot retraction were markedly defective compared with normal adults (table I). In addition, platelet factor 3 release in 10 normal infants, as measured by the modified Stypven time, was decreased when compared with 10 values for normal adults (fig.5). Other variables of platelet function (bleeding times, native blood platelet adhesiveness, petechiometer tests) studied in newborn infants were normal (table I). Thrombelastograms were compatible with hypercoagulability of the blood (table I). None of the infants studied had clinical evidence of a bleeding tendency.In vitromixing experiments suggested that the impaired ADP platelet aggregation was due neither to the presence of plasma ADP inhibitors, a refractory state due to increased circulating levels of ADP, anticoagulants, nor to a selected population of platelets. Physiologic alterations of infant platelets are similar to platelet functional changes observed in thrombasthenia.SpeculationTransient physiologic alterations have been described in many components of the newborn's blood, i.e., decreased plasma coagulation factors, red cell enzyme changes, low immunoglobulins, and an altered kinin system. It is not surprising, therefore, to find a transient platelet functional deficiency as well. Indeed, this hypofunction may be a defense against intravascular coagulation at a time when the infant's blood may be hypercoagulable and susceptible to increased thrombotic tendencies. Whether this platelet functional alteration could aggravate or be related to the cause of hemorrhage in severely ill infants remains to be shown.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractLiver biopsies were performed on three patients suffering from the nonketotic form of hyperglycinemia. Direct assay of the enzymes involved in glycine-serine conversion revealed that the enzymic defect underlying this disease was due to nonfunction or absence of a glycine cleavage system. This enzyme system catalyzes the conversion of glycine to hydroxymethyltetrahydrofolic acid, carbon dioxide, and ammonia. In patients with hyperglycinemia, serine to glycine conversion is normal and patients depend on this metabolic conversion for their supply of C1units. As glycine formed in this reaction cannot participate as a C1-unit donor, it cannot be metabolized further and consequently will accumulate.A therapeutic approach was devised to supply the organism with sufficient C1units and was achieved by addition of methionine to a diet devoid of serine and glycine.As a consequence, the patient with hyperglycinemia does not rely so heavily on the glycine-serine conversion to fulfill his requirements for C1units and glycine will not accumulate. Levels of glycine in plasma fell to normal values after feeding a diet with 0.3 g methionine/kg/24 h for a period of 10 days. It was demonstrated that the decrease in plasma glycine by administration of methionine was not due to increased excretion of glycine in the urine.SpeculationThese studies have yielded evidence that the nonketotic form of hyperglycinemia is due to absence or nonfunction of the enzymic system responsible for the conversion of glycine to CO2, NH3, and hydroxymethyltetrahydrofolic acid. To meet the requirements of the organism for C1units the conversion of serine to glycine proceeds at an accelerated rate. This can be compensated by addition of methionine to the diet, which serves as an alternate C1-unit donor. Patients with hyperglycinemia that do not respond to serine- and glycine-free diets may respond to diets rich in methionine.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractQuantitative studies of the ultrastructure of heart muscle in iron- and copper-depleted rats show an increased mitochondrial area that contributes to cardiac hypertrophy in both conditions. The mean ratios of mitochondrial/myofibrillar areas are 1.73 and 1.69, respectively, in the deficient groups compared with 0.70 in control animals. The markedly enlarged mitochondria appear to displace and distort the myofibrils. After iron-deficient rats are provided with iron, the reversal of the abnormal mitochondrial/myofibrillar ratio and of cardiac hypertrophy requires about 16 days or approximately twice as long as the complete repair of anemia.In heart muscle from iron-deficient animals, the mitochondrial cytochromes, which all contain iron, remain essentially normal in concentration. In the copper-deficient rats, in contrast, cytochromea+a3, which contains copper, is depressed to less than one-half the normal concentration. Isolated mitochondria from heart and liver of all animals deficient in iron and copper function normally with respect to respiration and phosphorylation. Thus, a correlation between abnormality of mitochondrial structure, composition, and function is not as yet apparent.The mitochondrial contribution to the cardiac hypertrophy of iron and copper deficiency cannot be attributed entirely to increased work load secondary to anemia, particularly in copper-deficient rats whose cardiac enlargement precedes the development of anemia. The morphologic changes are distinct from those observed in experimental work hypertrophy and can represent a response to the lack of essential precursors required for the cytochromes or other mitochondrial constituents.SpeculationCardiac hypertrophy in iron and copper deficiency is in part attributable to enlargement of the mitochondrial compartment. This results from the lack of trace metals required for the production of cytochromes or other mitochondrial constituents.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractThirty-one newborns with anencephaly had small kidneys; the weights of these organs were only 67% of the mean value for control infants of the same gestational age. Kidneys of the anencephalic infants had only 81% as many nephrons as kidneys of the control infants. In the kidneys of anencephalic newborns, tubular cells distal to the proximal convoluted tubules contained less cytoplasm than did comparable cells of control subjects. For example, in anencephalic infants, cells in the distal convoluted tubules had only 57% as much cytoplasm as control cells. Pituitary dysfunction may be directly or indirectly responsible for this maldevelopment, since in this study, an infant with isolated congenital absence of the pituitary had similar renal abnormalities while a newborn anencephalic infant with a normal parabiotic twin partner had near normal kidneys.SpeculationDysfunction of the hypothalmic—neurohypophyseal system might contribute to the hydramnios common in anencephalic gestations by leading to increased urine output by the fetus. In any case, nephron structure is so abnormal in anencephalic newborns that it should be interesting to test their renal function.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractConcentrations of free and conjugated bile acids in cord blood (30 samples) were within the adult range and were significantly higher than in serum from newborns (15 infants). Deoxycholic acid (D) was absent from sera of newborns and present in 7 of 23 cord samples. Only two of nine infants in year 1 of life showed detectable amounts of D. In 25 children, ages 1–13 years, bile acid concentrations in serum fell within the normal adult range. Small amounts of unconjugated bile acids were present in some specimens.Thirty-three children with cystic fibrosis of the pancreas (ages 2–14 years) had serum concentrations within the normal adult range. No correlation with age, sex, or severity of disease was noted.Thirty-two children with a variety of hepatobiliary disorders had significantly elevated concentrations of bile acids with the exception of a few infants with terminal cirrhosis. Determination of patterns and concentrations of bile acids in serum are of limited usefulness in differential diagnosis of these disorders.SpeculationThe estimation of bile acids in serum will have to be combined with measurement of bile acids in bile and study of excretion of fecal bile acids if evaluation of bile acid metabolism is to provide better understanding of hepatobiliary disease.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractIn 14 obese females and 9 obese males, body length was used as a base line for the detection of excess growth of lean and adipose tissue.Eighteen patients had increased lean body mass based on body water determinations (fig.1), and40K was found to be an unreliable diagnostic agent for the prediction of lean body mass. A similar number of patients had excessive amounts of intracellular mass (fig.2). Males had an increment in total protein content within the adipose tissue mass (table IV), whereas half of the females (and all those possessing advanced bone age) had increments in muscle mass (fig.3) and in the DNA content of their musculature (fig.4). A sufficient number of female patients were studied to document two classes of obesity—one group with, and one group without advanced maturation, excess nuclei (fig.4), and reduced protein/DNA (fig.5) in the musculature.Studies of noncollagen protein in adipose tissue mass of male subjects indicated an increase in the number of adipocytes compared with those found in normal or obese females (table IV). In addition, protein and water concentrations of adipose tissue were reduced in all the obese patients studied (table III). The extracellular volume was found to be constant at 17% of body weight in obese adolescent males.SpeculationObesity in adolescents is the result of genetic, environmental, nutritional, and hormonal factors. Over-nutrition in infancy influences hormonal secretion and produces advanced maturation and excessive cell growth in muscle (as found in this study in one group of obese females). Also, in one group of obese females, estrogens, which retard cell number increase (in the normal pubertal female), are possibly suppressed by androgens and thus allow androgen and growth hormone to exert maximal effects at the muscle level (increase of cell number).In the obese male, the superimposition of high levels of circulating insulin on androgen secretion enhances the growth of collagen and of adipocytes in the adipose tissue mass. Thus, the particular changes in body composition occurring in obesity are dependent on the sex of the individual.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractBlood glucose levels and rates of excretion of insulin in urine were measured in 31 infants with erythroblastosis. Twenty-two of these infants had determinations of insulin excretion in urine performed during the first 24 h of life. These infants can be divided into two groups. Group 1 were infants of greater than 36 weeks gestation. When using hemoglobin as the index of severity of the disease, they can be subdivided into two groups. Group 1A (six infants with a cord hemoglobin value of greater than 13 g/100 ml) had a mean excretion ratio of insulin/creatinine in urine of 6.9 μU/mg compared with a mean of 5.4 μU/mg for the control group (P= 0.5). Group 1 B (six infants with a cord hemoglobin value of less than 13 g/100 ml) had a mean value for insulin in the urine of 47.0 μU/mg, compared with a mean value of 5.4 μU/mg for the control group. Group 2, composed of 10 infants of less than 36 weeks gestation, had a mean value for insulin in urine of 129.7 μU/mg, compared with a mean of 21.9 μU/mg for the control group (P< 0.01). Excretion of insulin was inversely related to blood glucose. Seven infants were hypoglycemic (blood glucose levels of less than 20 mg/100 ml) and all had elevated insulin levels in urine.SpeculationIn erythroblastotic infants, simultaneous occurrence of islet cell hyperplasia, hypoglycemia, and hyperinsulinuria is indicative of increased insulin production. The cause of the islet cell hyperplasia is not apparent. The placenta is commonly hyperplastic, and hence, its ability to destroy insulin may be enhanced, thus causing islet cell hyperplasia. At birth, separation of the infant from the placenta leads to an abrupt decrease in the infant's rate of insulin destruction, and thus, to temporary over-production of insulin. This hypothesis is in keeping with the observed early hypoglycemia and the normal birth weight for gestational age.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractA group of patients is described with paramyotonia congenita whose condition was marked by a negative arterial-venous (A-V) difference in potassium concentration in plasma under basal conditions. The means ± SEM for arteriolized capillary blood, venous blood, and the differences between them were 4.13 ± 0.13, 5.05 ± 0.10, and −0.48 ± 0.08 mEq/liter, respectively. The A-V potassium difference in plasma becomes positive during exacerbation of signs and symptoms. The corresponding means ± SEM were 4.74 ± 0.17, 4.66 ± 0.15, and +0.08 ± 0.03 mEq/liter. The symptoms are precipitable by either chilling or administering potassium. Attacks of either myotonia or paresis were not associated with spontaneous hyperkalemia. The muscles of these patients contain increased amounts of water and sodium and decreased amounts of potassium.SpeculationIt is believed that the negative A-V potassium difference in plasma constitutes a marker that enables patients with paramyotonia congenita to be separated from patients with hyperkalemic periodic paralysis and myotonia. In the latter instance, myotonia is also precipitable by chilling and relieved by rest. There is a correlation between increased muscle water between attacks and the occurrence of myotonia in patients with the various forms of periodic paralysis.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

ExtractTwenty-six full-term infants delivered vaginally were studied. There were 16 males and 10 females. Capillary blood samples for glucose were obtained hourly. When the infant voided spontaneously, the urine collection for determination of epinephrine (E), norepinephrine (NE), metanephrine (M), normetanephrine (NM), and vanillylmandelic acid (VMA) was discontinued. Using the value of 30 mg/100 ml as the lower limit of normal for glucose in blood, the study patients were divided into three groups: group A (16 subjects), all values over 30 mg/100 ml; group B (5 subjects), one value under 30 mg/100 ml; group C (5 subjects), two or more values less than 30 mg/100 ml.Comparison of the means by groups revealed no significant differences in individual or total catecholamine excretions. The two patients who were judged to be the most severely hypoglycemic, however, showed the lowest epinephrine excretions of the entire study group. Nonparametric statistical analysis was used to compare the epinephrine excretion of the 16 patients who maintained a normal glucose level with that of the 10 patients of groups B and C. APvalue of less than 0.05 was obtained, suggesting that the ability to maintain adequate blood glucose was associated with a higher epinephrine excretion. Nonparametric statistical analyses did not show a significant difference in E+M or E+M+VMA excretion among the study groups. This negative finding does not support our hypothesis of deficient epinephrine release as a contributory factor in spontaneous neonatal hypoglycemia.Gatecholamines in urine were determined in nine newborns who were treated in a fashion similar to the study groups except that they were not subjected to heel punctures as repeated unpleasant stimuli. The results, expressed as mean ± SD were: E, 7.73 ± 5.36; NE, 35.3 ± 22.9; M, 52.8 ± 33.9; NM, 201 ± 140; and VMA, 899 ± 356 ng/kg/h. The only significant difference between these values and those of the study group lay in the levels of epinephrine excretion where significant differences were found between these subjects and those in group A. It appears reasonable to attribute the observed difference to the lack of stimulation by heel punctures.A rise in blood glucose concentrations was observed after epinephrine injection in all groups, with no differences between them.SpeculationThese results suggest that in certain instances failure of endogenous epinephrine release may play a role in spontaneous hypoglycemia of the newborn. A major unresolved question is whether this failure of epinephrine release is itself primary, or whether asymptomatic hypoglycemia is not a sufficient stimulus for adrenal activation in these children.

ISSN:0031-3998    

出版商:OVID    

年代:1970

数据来源: OVID