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Biomedical subjects

R M Pitkin

Publications and source records attributed to R M Pitkin.

At least 19 recordsLinked to original sources
PubMed1979

Platelet and leukocyte counts in pregnancy.

Platelets and leukocytes in venous blood were counted with automated methodology in 23 women studied longitudinally throughout pregnancy and at six weeks after delivery. The average platelet count declined monotonically in a manner consistent with the gestational increase in blood volume. Total leukocyte count rose early in gestation and remained elevated, with neutrophils accounting for the changes. Absolute neutrophil counts during gestation were nearly twice those of the same women postpartum (5.76 vs 3.13/cu mm x 10(-3).) The monocyte count also tended to increase, whereas lymphocytes, eosinophils, and basophils declined in number.

Basophils↗
PubMed1979

Effects of magnesium sulfate treatment on perinatal calcium metabolism. I. Maternal and fetal responses.

Serial maternal and cord blood determinations of the ions and hormones involved in calcium homeostasis were made in pre-eclamptic women treated with intravenous magnesium sulfate. A 4 gm loading dose followed by 1 to 2 gm/hr caused maternal serum magnesium concentrations to rise 150%, to levels of 3.3 to 4.5 mEq/L, and ionized calcium levels to fall 16%, to 1.89 mEq/L. The hypocalcemia etly altering calcitonin. Changes in total calcium paralleled those of ionized calcium; phosphorus levels were not affected by magnesium infusion. At the time of delivery the offspring of these women were hypermagnesemic and relatively hypocalcemic, although less so than their mothers. Fetal ionized calcium levels, although lower with magnesium treatment than in control subjects, were within the lower limits of the normal range, which perhaps explains why the fetus did not respond with increased PTH or decreased calcitonin output. These results indicate that the principal maternal response to magnesium-induced hypocalcemia involves increased parathyroid hormone secretion which tends to preserve maternal calcium homeostasis, while the fetus is partially protected from hypermagnesemia and hypocalcemia by the placenta.

Adult↗
PubMed1979

Calcium metabolism in normal pregnancy: a longitudinal study.

Total and ionic calcium, magnesium, phosphorus, albumin, and immunoreactive parathyroid hormone (iPTH) and calcitonin (iCT) were measured in serum or plasma from 30 women throughout pregnancy (beginning before 12 weeks' gestation) and the puerperium. Total calcium levels declined during gestation, paralleling a progressive fall in albumin concentration, whereas ionic calcium values declined only very slightly. Although iPTH levels in early pregnancy were lower than postpartum values (suggesting that iPTH may decline initially following conception), the major portion of gestation was characterized by progressively increasing concentrations which at term averaged 53% above early pregnancy levels and 33% above puerperal values. Thus, the principal adjustment during pregnancy is "physiologic hyperparathyroidism" which acts to preserve maternal homeostasis by maintaining the concentration of calcium ions in extracellular fluid in the presence of expanding fluid volume, increased renal function, and placental transfer. iCT levels were not affected consistently by pregnancy and exhibited highly variable patterns; half of the subjects demonstrated an increase during the first and second trimesters and then a decline in the third trimester and the remaining half was equally divided between those with no change and those with progressively falling levels.

Adult↗
PubMed1979

Maternal-perinatal calcium relationships.

Serum concentrations of total and ionic calcium, magnesium, phosphorus, and albumin were measureed in maternal and cord blood of 115 near-term deliveries. The same measurements (except for ionic calcium) were made in blood obtained from corresponding newborns at 24 hours of age. Cord levels of all components exceeded maternal values, and maternal and cord levels correlated significantly with each other. In the case of calcium, the cord-maternal difference involved both ionic and protein-bound forms. Significant umbilical arterio-venous differences were found only in the case of total calcium, and this difference reflected variation in the protein-bound form only. During the first 24 hours postpartum, total calcium concentration fell (by an average of 0.75 mEq/liter), phosphorus levels rose (by an average of 0.63 mg/dl), and magnesium and albumin did not change significantly. Cord levels of all agents correlated significantly with corresponding neonatal values. In view of the significant positive relationships demonstrated between maternal and cord levels and between cord and neonatal levels, these results substantiate the importance of the maternal serum ionic calcium concentration in normal perinatal calcium homeostasis.

Calcium↗
PubMed1978

Urinary urea-nitrogen ratio as an index of protein nutrition in diabetic pregnancy.

Urinary urea nitrogen-total nitrogen ratio (UN/TN) was measured at intervals throughout pregnancy in 12 normal women and in 10 with insulin-dependent diabetes mellitus and the results were related to protein ingestion estimated by dietary history. While urea and nitrogen correlated significantly with each other in both normal and diabetic subjects, the relationship between UN/TN and protein intake was quite different in the two groups. Nondiabetic patients exhibited generally close correlation between UN/TN and protein intake with statistically significant correlation coefficients (r = 0.74-0.99) in 11 of 12 subjects. In none of the 10 diabetic patients, however, was significant correlation found. While the reliability of the index in diabetic patients tended to improve as hyperglycemia lessened, even under conditions considered clinically to indicate excellent metabolic control (mean plasma glucose less than or equal to 125 mg/dl), UN/TN still did not correlate significantly with protein intake. These observations suggest that the unstable carbohydrate metabolism characteristic of diabetes mellitus may be responsible for altered protein retention during pregnancy. From a clinical point of view, the utility of urinary urea studies as a simple and objective index of protein intake in the normal pregnant women does not apply in the diabetic patients.

Adult↗
PubMed1978

Laminaria as an adjunct in induction of labor.

The safety and efficacy of laminaria tents as an adjunct to labor induction near term were examined in a prospective, controlled, and randomized study involving insertion of laminaria into the cervical canal the evening prior to planned induction. Six of 35 subjects in whom laminaria were used entered labor spontaneously and delivered overnight, compared with 1 of 39 controls. Of the remainder, the Bishop score increased an average of 3.7 points, a highly significant change, in the laminaria-treated group compared with no change in the controls. Labor, induced primarily by amniotomy with intravenous oxytocin then given to patients in whom regular contractions did not begin within 8 hours, was shorter with laminaria use than in controls, though the amniotomy-to-delivery interval did not differ significantly. However, comparison of the subgroup with cervices relatively unfavorable for induction, indicated by an initial Bishop score of 5 or less, showed both length of labor and amniotomy-to-delivery interval to be significantly shorter (each by an average of 3 hours) in the laminaria-treated group compared with controls. Complications, including febrile morbidity, did not differ. We conclude that laminaria tents are both effective and safe as an adjunct to labor induction, acting by accelerating the preparatory changes in the cervix which normally occur in late pregnancy.

Dilatation↗
PubMed1978

Calcium-regulating hormones during the menstrual cycle.

Calcium metabolism during the menstrual cycle was studied in seven women from whom fasting blood samples were drawn daily or every other day throughout ovulatory cycles. Total calcium (Ca), ionic calcium (Ca++), magnesium (Mg), phosphorus (P), and immunoreactive parathyroid hormone (PTH) and calcitonin (CT) were measured. LH levels were used to date each cycle and progesterone levels were used to confirm ovulation. Plasma estradiol was measured in two of the subjects. In six subjects with cycle lengths of 27-31 days, PTH levels rose progressively through the follicular phase to a peak at or slightly before the LH surge, then fell progressively through the luteal phase; peak PTH levels were 30-35% above early follicular and late luteal values. CT levels were also highest at midcycle, but the CT pattern was somewhat more variable than that of PTH. Ca++ tended to fall until 3-4 days before ovulation and then to increase, while Ca, Mg, and P exhibited no particular pattern. One subject experienced a prolonged (44 day) ovulatory cycle characterized by three distinct PTH peaks, each of which coincided with elevations in plasma estradiol level. These results represent the first report of menstrual cyclicity in calcium-regulating hormones. The timing suggest an estrogen effect and it is hypothesized that estrogen inhibits PTH-induced bone resorption, lowering serum Ca++, which in turn provokes a compensatory PTH output. With the decline of the preovulatory estrogen peak, Ca++ levels rise and PTH secretion falls. Alternatively, it is possible that the primary action may be an estrogen-induced rise in CT release, causing hypocalcemia and consequent PTH output. Cyclic changes in PRL release or vitamin D metabolism might also be involved.

Calcitonin↗
PubMed1978

Radioimmunoassay of calcitonin in the plasma of rhesus monkey and man.

We describe a radioimmunoassay for rhesus monkey and human immunoreactive calcitonin, in which a selected goat anti-human calcitonin antiserum, 131I-labeled synthetic human calcitonin tracer, and purified synthetic human calcitonin standards were used. The mean basal concentration of calcitonin in normal monkey plasma (254 microgram/liter) was not significantly different from that in normal human plasma (217 microgram/liter). The data indicate that the method is sensitive (lower limit of detection, 5 ng/liter), specific, accurate, and reproducible (coefficient of variation, 1-11% over a wide range of concentrations). Monkey calcitonin response to changes in plasma calcium concentration is similar to that in man, with significant correlation between calcium and calcitonin concentrations. Use of this radioimmunoassay for monkey and human calcitonin allows the monkey to be used in further studies of factors regulating secretion, function, and metabolism of calcitonin under various experimental conditions that would not be feasible in man.

Animals↗
PubMed1977

Serum calcium concentrations in human pregnancy.

Total and ionic calcium concentrations were measured in maternal serum from nonpregnant (N=30), pregnant (N=137), and early puerperal (N=17) women. In this cross-sectional study, total calcium levels (measured by atomic absorption spectrophotometry) exhibited the previously described pattern of a decline beginning in the first trimester and continuing until approximately 32 weeks, with a slight terminal rise from thence to term. Mean (+/-SD) values for the three trimesters were 4.80 (+/- 0.13), 4.56 (+/- 0.14), and 4.46 (+/-0.16) mEq. per liter, respectively, with all differences statistically significant. Ionic calcium levels (measured by calcium flow-through electrode) declined to a lesser (though still statistically significant) degree; mean (+/- S.D.) values for the three trimesters were 2.33 (+/-0.07), 2.28 (+/-0.08), and 2.24 (+/-0.06) mEq. per liter, respectively. Because of the differential rates of fall, the proportion of total calcium represented by the ionic component increased progressively during gestation. The results indicate that the major portion of the characteristic decline in maternal serum total calcium concentration with pregnancy reflects changes in the nonionized (albumin-bound) fraction while the ionic portion declines only slightly. The concentration of calcium ions in serum is maintained within a very narrow physiologic range throughout gestation.

Calcium↗
PubMed1977

Nutritional influences during pregnancy.

Maternal nutrition represents one of the important influences on the course and outcome of pregnancy and attention to nutritional factors (i.e., assessment of nutritional status, dietary advice, and follow-up evaluation) properly constitute an essential component of prenatal care. Nearly all nutrients are required in increased amounts during gestation but the magnitude of the increase varies from nutrient to nutrient. Caloric needs increase by 300 kcal per day, representing an addition of 15 per cent, and should be sufficient to support a weight gain averaging 350 to 400 gm per week during the last two trimesters. Total protein intake during pregnancy should be 1.3 gm per kg for the mature woman and somewhat higher for the adolescent. Gestational needs for iron cannot be met by diet and supplementation (in the form of simple ferrous salts, 30 to 60 mg daily) should be provided. Folate requirements are doubled during pregnancy and, while these can be met by diet, supplementation may be considered as an option. Provision of the gestational calcium allowance from food sources is readily possible if (and only if) daily products are consumed. The generally increased need for other nutrients can be provided readily by the properly selected diet. Thus, with respect to supplements, iron and perhaps folate should be advised routinely while other vitamin-mineral supplements are probably neither helpful nor harmful. Prescription of vitamin-mineral supplements cannot be expected to compensate for poor dietary habits. Dietary restriction of nutrients in general, and energy and sodium in particular, has the potential for impairing the maternal capacity to make the required physiologic adjustments of pregnancy and interfering with fetal development. Restriction of any nutrient to levels below the guidelines provided by the Recommended Dietary Allowances is rarely if ever advisable.

Ascorbic Acid↗
PubMed1977

Placental transfer of glucose-amino acid complexes present in parenteral solutions.

Intravenous infusion of glucose-amino acid complexes, formed during heat sterilization of mixtures of glucose and amino acids or protein hydrolysates, has been associated with mild dehydration in infants, and with excessive trace metal ion excretion in both infants and adults. When parenteral solutions containing these glucose-amino acid complexes were infused into pregnant rhesus monkeys, the compounds accumlated in the maternal plasma and were transported to the fetal circulation. Although all of the compounds studied crossed the placenta, fetal levels were consistently lower than maternal levels. Amniotic fluid concentrations of these compounds increased progressively with the length of maternal infusion, presumably through fetal urination into the amniotic sac. In animals infused with solutions not heat sterilized, levels of these compounds could not be detected in maternal plasma and urine, fetal plasma and urine, or in amniotic fluid. In view of possible toxicity of the glucose-amino acid complexes, parenteral solutions containing these compounds should probably be avoided in the intravenous nutrition of the pregnant woman.

Amino Acids↗
PubMed1977

Radioimmunoassay of parathyroid hormone (parathyrin) in monkey and man.

A radioimmunoassay for rhesus monkey and human immunoreactive parathyrin was developed in which a selected anti-bovine parathyrin antiserum, radioiodinated purified bovine parathyrin tracer, and human parathyroid tissue-culture media standards were used. The resulting data indicate that (a) the method is sensitive, specific, accurate and reproducible; (b) it is valid for both the rhesus monkey and the human; (c) the serum immunoreactive parathyrin concentration of the monkey is essentially the same as that in man; (d) monkey immunoreactive parathyrin responds to changes in serum calcium concentration similarly to that in man; and (e) the rhesus monkey is therefore a suitable species in which to study parathyroid physiology, from which conclusions can be applied to the human.

Adult↗
PubMed1977

Drugs and the fetus.

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Drug-Related Side Effects and Adverse Reactions↗