Biomedical subjects
Publications and source records attributed to M G Ross.
Herpes genitalis is commonly seen by the obstetrician-gynecologist. Prolonged persistence of herpes is unusual and may herald an underlying disorder. A case of chronic primary herpes is presented, in which the diagnosis of acquired immunodeficiency syndrome was delayed because of a low degree of suspicion.
The contraction stress test has been widely used to manage high-risk pregnancies. Breast-stimulated uterine contractions have been assumed to be mediated through oxytocin release. We studied 20 women undergoing a breast-stimulated contraction stress test. There was no significant increase in plasma oxytocin levels during this study in either test responders or nonresponders. These results suggest that the presence of a breast stimulation-uterine contraction reflex is not mediated by oxytocin.
Prematurity, the major cause of perinatal morbidity and mortality, results from a multifactorial interaction of medical, historic, and psychosocial conditions. Although the literature contains several reports of prematurity risk-scoring systems, the relative importance of specific risk factors may depend on the population studied. This report represents the first prematurity risk-scoring system designed specifically for a predominantly Hispanic population in the United States. Retrospective analysis of 8240 births occurring at Harbor/UCLA Medical Center from July, 1979 to December, 1982 identified maternal prenatal risk factors that were found to be statistically related to prematurity. A linear logistic regression model was then employed to derive a composite risk score. Using the logistic risk scores, we developed a simplified model for identifying women at risk for preterm birth. The methodology and analyses provide a system for the development of population-specific risk scoring.
Amniotic fluid volume reflects a balance between fetal lung fluid and fetal urine production and fluid reabsorption via fetal swallowing. Arginine vasopressin (AVP) infusion decreases both fetal lung fluid and urine production and increases amniotic fluid osmolality and AVP concentration. In the present study we assessed the effect of amniotic fluid AVP injection on plasma AVP (n = 6) and renal function (n = 4) in chronically catheterized fetal lambs (X gestation = 130 days). Thirty minutes after addition of 25 micrograms of synthetic AVP into the amniotic cavity, mean +/- SE fetal plasma AVP increased from a base line of 2.7 +/- 0.2 to 14.6 +/- 3.4 pg/ml (P less than 0.01). One hundred and twenty minutes after injection, plasma AVP had increased to 26.9 +/- 5.7 pg/ml. Fetal urine volume did not change (0.78 +/- 0.01 ml/min) but significant increases in urine osmolality (169 +/- 19 to 315 +/- 25 mosm) and urine sodium (64 +/- 11 to 125 +/- 11 mueq/ml) were observed 120 min after AVP administration. In conclusion, amniotic fluid AVP levels can affect fetal plasma AVP concentration, and AVP absorbed from the amniotic fluid by the fetus remains biologically active.
Chronically prepared third trimester fetal lambs were administered intravenous infusions of nitropruside. Mean basal systolic and diastolic blood pressure (59.8 and 42.4 mmHg, respectively) decreased significantly during the infusion (49.2 and 36.8 mmHg, respectively) and increased significantly during the recovery period (66.4 and 48.5 mmHg, respectively). Fetal plasma arginine vasopressin (AVP) significantly increased from a mean basal level of 1.25 +/- 0.09 to 6.81 +/- 0.39 pg/ml during the hypotensive period. Urinary AVP basal levels of 1.21 +/- 0.13 pg/ml increased to 3.18 +/- 0.66 pg/ml during the hypotensive period and 5.87 +/- 0.82 pg/ml during the recovery period (P less than 0.05). The fetal urinary response to nitroprusside appeared biphasic. The hypotensive phase was marked by decreases in both free water and osmolar clearances. During the recovery phase free water clearance remained decreased, while osmolar clearance returned to basal levels. Thus AVP secretion represents an important mechanism for ovine fetal modulation of solute and water excretion in response to utero hypotensive stress.
Intravascular hemorrhage of the ovine fetus is a potent stimulus for arginine vasopressin (AVP) secretion. However, the method (acute, continuous) and rate of blood withdrawal may influence the fetal response. To determine the hemorrhage threshold for AVP secretion in response to slow continuous hemorrhage, five chronically catheterized ovine fetuses were continuously hemorrhaged (0.6% blood vol/min) to 24-30% blood volume withdrawal. Immediately after hemorrhage fetal blood was reinfused at an equivalent rate. In addition to AVP measurements by radioimmunoassay, fetal urinary responses were monitored as an index of fetal AVP secretion. Significant increases in plasma AVP occurred during hemorrhage (1.0 +/- 0.1 to 8.0 +/- 2.0 pg/ml). The fetal plasma AVP-hemorrhage threshold, as defined by regression analysis, occurred at withdrawal of 13.0% blood volume. Fetal urine volume significantly decreased from a mean basal rate of 0.59 +/- 0.03 to 0.21 +/- 0.06 ml/min at the completion of hemorrhage. Urinary sodium, potassium, and osmolar excretion also significantly decreased at the completion of hemorrhage. Urinary AVP excretion, urine osmolality, sodium, and potassium concentrations did not change significantly during the hemorrhage period but increased significantly during the reinfusion period; the delay a result of renal and catheter dead space. Reinfusion of blood resulted in a return of plasma AVP to basal levels. These results define a threshold for AVP secretion and demonstrate significant urinary effects in response to slow continuous hemorrhage.
The neuropeptides arginine vasopressin (AVP) and arginine vasotocin (AVT) are present in ovine fetal plasma in similar concentrations. Although AVP appears to be an important factor in the regulation of fetal water metabolism, the significance of AVT in the fetus is not clear. In the present study we assessed the effects of changes in steady plasma AVT levels on renal and cardiovascular function of fetal lambs (mean gestation, 128 days) maintained with vascular and bladder catheters. Successive 1-h infusions of synthetic AVT (n = 8) at rates of 1.0 and 2.0 ng/min X kg resulted in steady state plasma AVT levels of 30 +/- 7 and 59 +/- 12 pg/ml, respectively. The AVT infusions increased both urinary AVT concentrations and urinary AVT excretion. Plasma and urinary AVT clearance rates (45 +/- 8.4 ml/min X kg and 0.38 +/- 0.13 ml/min, respectively) remained constant over the observed range of plasma AVT levels. Urinary AVT clearance accounted for less than 1% of the total plasma AVT clearance and was nonsaturable. Increases in plasma AVT augmented urinary osmolar excretion and osmolar clearance, and evoked a significant natriuresis. AVT at either 1 or 2 ng/min X kg decreased fetal heart rate and tended to increase blood pressure. These results suggest that AVT, like AVP, may be important in modulating ovine fetal electrolyte homeostasis.
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Decreased free water excretion and the development of interstitial edema are recognized characteristics of preeclampsia. However, the pathophysiology of decreased urine excretion in preeclampsia is presently controversial: diminished glomerular filtration, renal arteriolar spasm, elevated plasma vasopressin levels, and plasma volume contraction have been suggested as etiologies. We studied seven pregnant patients with a diagnosis of mild preeclampsia to assess the role of vasopressin, serum protein, and glomerular function in the renal excretion of water. The ability to excrete a water load was significantly and directly correlated with serum albumin (P less than 0.05) and protein (P less than 0.02) concentrations. Neither plasma vasopressin nor creatinine clearance correlated with water excretion. The similarity of preeclampsia and the nephrotic syndrome with regard to the renal excretion of water is discussed.
Antibodies to cytomegalovirus (CMV) and Epstein-Barr virus capsid antigen (EBVCA) were examined in 41 patients with rheumatoid arthritis (RA), 26 patients with primary sicca syndrome, and 26 healthy subjects of similar age and sex. IgG antibody titres to EBVCA and CMV were similar in all three groups, apart from a trivial increase of antibodies to EBVCA in RA. False positive IgM anti-CMV antibodies detected in serum from one patient with sicca syndrome and 20 patients with RA were shown to be due to rheumatoid factors. These data did not support recent suggestions that patients with these diseases showed exaggerated immunological responses to either virus and emphasised the need to incorporate adequate laboratory and disease controls when seroepidemiological studies are performed on sera containing rheumatoid factors and autoantibodies.
Chronically prepared, third trimester fetal lambs were administered 72-h intravenous infusions of arginine vasopressin (AVP) (65 or 130 mU/kg h) or 0.9% saline. Saline infusion preceding the AVP infusion did not change amniotic fluid (AF) composition. During the AVP infusion, there were significant increases in amniotic fluid osmolality (278.8 +/- 4.9 to 302.1 +/- 4.5 mosm) and in sodium (122.7 +/- 3.3 to 135.3 +/- 3.6 meq/l) and potassium (9.7 +/- 2.6 to 13.8 +/- 1.3 meq/l) concentrations. Saline infusion after the AVP infusion resulted in return of AF osmolality, sodium, and potassium toward normal levels. Fetal plasma and amniotic fluid AVP levels measured by radioimmunoassay significantly increased during AVP infusion and decreased during the subsequent saline infusion. There were no changes in maternal or fetal plasma osmolality in response to AVP. These results suggest that fetal AVP released in response to intrauterine stress may alter the composition and osmolality of amniotic fluid in a reversible manner.
The pineal gland indolamine melatonin now appears to be a primary mediator of the timing of estrus in mammals. Because the neurohypophyseal nonapeptides arginine vasotocin and oxytocin have recently been identified in the pineal glands of several species, we sought to assess the possibility of an interaction between melatonin and the neurohypophyseal hormones. An acute melatonin infusion (216 mumol) was administered to pregnant and nonpregnant ewes. Although plasma arginine vasopressin and arginine vasotocin levels did not change, melatonin produced a significant increase in plasma oxytocin in the nonpregnant though not the pregnant ewe. These data suggest a possible interaction between melatonin and oxytocin in the integration of mammalian reproduction cycles.
Arginine vasotocin ([8-arginine]-oxytocin) (AVT), the primary antidiuretic principle in submammalian vertebrates, has been reported to be present in mammalian pituitary and pineal glands. Although the most phyletically ubiquitous of the known neurohypophysial peptides, AVT is still not recognized as a mammalian hormone. We examined plasma, urine, and amniotic fluid from fetal lambs by radioimmunoassay (RIA) for evidence of AVT to assess the possibility of its being such a hormone. Measureable quantities of AVT-like immunoreactivity (irAVT) were observed in fetal plasma (2.4 +/- 0.2 pg/ml), urine (1.4 +/- 0.2 pg/ml), and amniotic fluid (1.9 +/- 0.2 pg/ml). Since the AVT antiserum shows minimal cross-reactivity with arginine vasopressin (AVP) and oxytocin (OT), measurements of AVP and OT concentrations in the same biological fluids also were conducted with specific antisera. The results suggest that the irAVT was not accountable on the basis of cross-reaction. To further verify the identity of the irAVT, a high pressure liquid chromatography system using RIA as a means of detection was developed. This system is sufficiently sensitive to allow the separation and quantitation of picogram quantities of the synthetic peptides AVT, AVP, and OT. In this system, the irAVT in fetal plasma, urine, and amniotic fluid appeared as a single peak coeluting with synthetic AVT. These results indicate that AVT is present in ovine fetal plasma and support the view that the fetus secretes this peptide. The physiological significance of circulating AVT remains to be defined.
To examine the effect of prolactin (PRL) on transplacental water flow, we infused mannitol (500 ml; 20% solution) over 10 min into five chronically catheterized ewes (121-134 days' gestation), producing a peak maternal plasma osmolality by 10 min and fetal osmolality by 20 min. One day before or after, an identical amount of mannitol was infused into the same ewe during the 2nd h of a 2-h infusion of PRL (40 +/- 2.2 micrograms/h) into a fetal leg vein. Mean (+/- SE) fetal plasma PRL levels were 6.9 +/- 3.2 ng/ml at baseline. Steady state fetal PRL levels were 17.7 +/- 7.4 ng/ml during PRL infusion. Maternal mannitol infused without administration of PRL to the fetus evoked a rise in fetal plasma osmolality similar to that following maternal mannitol during PRL administration to the fetus. Thus, as shown previously, PRL affects water permeability across the membranous chorioamnion, whereas results of the present study indicate that the hormone does not affect water transfer across the ovine chorionic villi (placenta).
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The fetal lung, filled with fluid during intrauterine life, is recognized as a site of fluid production, significantly contributing to amniotic fluid volume. To assess possible hormonal control of lung liquid production, we studied the effect of intravenous vasopressin or vasotocin on lung liquid production in chronically catheterized fetal sheep. Both vasopressin and vasotocin infusion resulted in a significant decrease in lung fluid production (38% and 40%, respectively) when compared to that in control animals receiving saline infusion. There was no significant change in lung fluid osmolality, sodium, or potassium. These findings suggest that lung liquid production in utero may be regulated by the fetus and that vasopressin or vasotocin may be of physiologic importance in lung fluid dynamics during the third trimester of ovine pregnancy and perhaps during parturition.
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Impetigo herpetiformis is a rare and often serious pustular dermatosis of pregnancy. The usual course of impetigo herpetiformis is one of continued progression throughout pregnancy with rapid resolution during the puerperium. This patient is the first reported case, to the authors' knowledge, of impetigo herpetiformis presenting during the puerperium, a time usually associated with the disease's remission. This suggests that impetigo herpetiformis should be included in the differential diagnosis of puerperal fever, particularly in those cases associated with dermatoses.