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Biomedical subjects

M Pearl

Publications and source records attributed to M Pearl.

At least 19 recordsLinked to original sources
PubMed1995

Problems associated with early discharge of newborn infants. Early discharge of newborns and mothers: a critical review of the literature.

OBJECTIVE: To determine whether research supports the advisability of early discharge of healthy newborns and mothers. METHODS: Critical review of English-language literature cited in the Index Medicus or the International Nursing Index. FINDINGS: No adequately designed studies have examined discharge before 48 hours after delivery without additional postdischarge services. Few studies have examined the consequences of recommending a clinic visit within the first days after discharge; studies of this practice among low-income populations found high no-show rates. Some small studies suggest that early discharge is likely to be safe for selected populations at low psychosocial, socioeconomic, and medical risk, with careful antenatal screening and preparation and multiple postpartum home visits. Some studies suggested adverse outcomes associated with early discharge even with early follow-up. CONCLUSIONS: Published research provides little knowledge of the consequences of short maternal/newborn hospital stays or varying postdischarge practices for the general population. The studies that have concluded that early discharge was safe were applied under restricted circumstances or were too small to detect clinically significant effects on important outcomes. Further research is needed to inform clinical and reimbursement policy on health services in the first days of life and parenting. Rigorous studies of sufficient size are needed to examine the impact of different hospital stays and different postdischarge practices on a range of outcomes for mothers and newborns in diverse populations and settings. Given a priori concerns, decisions on neonatal/obstetric discharge planning should be made cautiously.

Adult↗
PubMed1994

Potential acceptability of ovulation detection kits and RU-486 at two college campuses.

Two innovations in fertility research may expand birth control options in the United States. Ovulation detection kits, used alone or in conjunction with barrier methods of contraception, could be used to chart the fertile period. RU-486, when used in conjunction with a prostaglandin, induces early abortion, providing an alternative to conventional vacuum aspiration abortion. To measure the hypothetical acceptability of these methods, the authors surveyed 710 women at two college campuses in California regarding potential use of ovulation detection kits and RU-486. Seventy-one percent of the women in the final sample indicated an interest in using ovulation kits. Of these women, most (72%) were interested in using an ovulation detection kit as a supplement to barrier methods, and 22% indicated they would consider the kit as a sole method of birth control. More than 68% of the women in the sample indicated they would choose an abortion if faced with an unwanted pregnancy, and 60% would hypothetically choose RU-486 in preference to a conventional pregnancy termination. The most frequently cited reason for preferring RU-486 rather than conventional methods of abortion was to avoid the risks associated with the vacuum aspiration technique.

Abortion, Induced↗
PubMed1989

Nuclear imaging and the assessment of human Fc receptor function: studies in systemic lupus erythematosus.

In vivo immune clearance of immunoglobulin G sensitized autologous erythrocytes (rbc) was studied in nine patients who fulfilled American Rheumatism Association (ARA) criteria for systemic lupus erythematosus (SLE). Opsonized rbc were radiolabelled with technetium 99. The rate of radioactive blood clearance was measured, as was organ-specific radioactive uptake utilizing area-of-interest (AOI) measurements in a computerized scintigraphic imaging system. It was shown that dynamic quantitation of an AOI corresponding to the heart generated time-activity curves which approximated blood-clearance curves. Calculation of first order clearance (min per 50% decrease in counts) showed a highly significant correlation between rates derived from heart AOI curves and those derived from blood-clearance curves (r = 0.9483, P = 0.0003). Clearance curves showed a monoexponential slope in most patients. Further exploration of organ-specific AOI curves showed that percent splenic uptake and the nature of the splenic uptake curves varied between patients. These studies point toward a variable splenic role in Fc receptor function for SLE patients and further demonstrate the utility of nuclear imaging in studying immune clearance.

Adult↗
PubMed1987

Cytosolic calcium and the action of vasopressin in toad urinary bladder.

The effects of experimental procedures believed to increase cytosolic calcium on basal and vasopressin-stimulated osmotic water flow and transepithelial sodium transport were examined in the toad urinary bladder. Exposure of isolated toad bladders to quinidine, calcium ionophores (A23187, X537A), or low-sodium or potassium-free serosal solutions resulted in a dose-dependent decrease in the hydrosmotic response to vasopressin or exogenous adenosine 3',5'-cyclic monophosphate (cAMP). The degree of inhibition of cAMP-induced water flow induced by low-sodium or potassium-free serosal bathing media varied, and in a similar manner, with the serosal calcium concentration. The effects of quinidine sulfate (2 X 10-4 M), X537A (2 X 10(-5) M), and low serosal sodium (20 mM), but not that of A23187 (10(-5) M), were readily reversible. Exposure to quinidine (4 X 10(-4) M), A23187 (10(-5) M), X537A (5 X 10(-6) M), or low serosal sodium (2 mM) also inhibited the basal short-circuit current (SCC). Vasopressin, 4-20 mU/ml, completely overcame the inhibition of the SCC induced by quinidine, A23187, or low serosal sodium, but a submaximal dose of hormone (4 mU/ml) failed to fully reverse the inhibitory effect of X537A, 5 X 10(-6) M. These results are consistent with the view that 1) a Na-Ca exchange process operates across the basolateral surface of the granular epithelial cells of the toad urinary bladder in vivo, and 2) the level of free calcium in the granular cell cytosol plays a modulatory role in the control of apical membrane water and sodium permeability by vasopressin, and in the regulation of the basal rate of transepithelial sodium transport.

Animals↗
PubMed1985

Anion transport inhibitors: effects on water and sodium transport in the toad urinary bladder.

Acidification of the medium bathing the serosal surface of the toad urinary bladder results in impairment of the water permeability response to vasopressin. The magnitude of the hydrosmotic response to a maximal concentration of either vasopressin or the cyclic nucleotide analogue 8-(p-chlorophenylthio)-cyclic 3',5'-adenosine monophosphate (C1PhS-cAMP) was progressively reduced when serosal bath pH was decreased from 8.5 to 6.5. The disulfonic stilbenes SITS and DIDS and the diuretic furosemide, agents known to interfere with anion transport and with the regulation of intracellular pH in other tissues, inhibited the water flow response to vasopressin and C1PhS-cAMP in a pH-dependent manner when added to the serosal bathing medium. Inhibition of the hydrosmotic response to 10(-5) M C1PhS-cAMP was estimated to be half-maximal at 1.5 X 10(-4) M SITS, 2 X 10(-5) M DIDS, and 1 X 10(-5) M furosemide. The degree of inhibition induced by the anion transport inhibitors varied inversely with the concentration of exogenous cyclic nucleotide. SITS, DIDS, and furosemide had no effect on either basal or vasopressin-stimulated short-circuit current at serosal pH 8.5; all three agents inhibited basal short-circuit current at pH 7.1 but had no effect on the natriferic response to vasopressin. These results are consistent with the view that changes in intracellular hydrogen ion and/or anion concentration can selectively inhibit the increase in water permeability elicited by vasopressin at a step(s) distal to the generation of cAMP.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1984

Studies on the spectrin-like protein from the intestinal brush border, TW 260/240, and characterization of its interaction with the cytoskeleton and actin.

The terminal web of the intestinal brush border contains a spectrin-like protein, TW 260/240 (Glenney, J. R., Jr., P. Glenney, M. Osborne, and K. Weber, 1982, Cell, 28:843-854.) that interconnects the "rootlet" ends of microvillar filament bundles in the terminal web (Hirokawa, N., R. E. Cheng, and M. Willard, 1983, Cell, 32:953-965; Glenney J. R., P. Glenney, and K. Weber, 1983, J. Cell Biol., 96:1491-1496). We have investigated further the structural properties of TW 260/240 and the interaction of this protein with actin. Salt extraction of TW 260/240 from isolated brush borders results in a loss of terminal web cross-linkers primarily from the apical zone directly beneath the plasma membrane. Morphological studies on purified TW 260/240 using the rotary shadowing technique confirm earlier results that this protein is spectrin-like and is in the tetrameric state in buffers of low ionic strength. However, examination of TW 260/240 tetramers by negative staining revealed a molecule much straighter and more uniform in diameter than rotary-shadowed molecules. At salt concentrations at (150 mM KCl) and above (300 mM KCl) the physiological range, we observed a partial dissociation of tetramers into dimers that occurred at both 0 degree and 37 degrees C. We also observed (in the presence of 75 mM KCl) a concentration-dependent self-association of TW 260/240 into sedimentable aggregates. We have studied the interaction of TW 260/240 with actin using techniques of co-sedimentation, viscometry, and both light and electron microscopy. We observed that TW 260/240 can bind and cross-link actin filaments and that this interaction is salt- and pH-dependent. Under optimum conditions (25-75 mM KCl, at pH 7.0) TW 260/240 cross-linked F-actin into long, large-diameter bundles. The filaments within these bundles were tightly packed but loosely ordered. At higher pH (7.5) such bundles were not observed, although binding and cross-linking were detectable by co-sedimentation and viscometry. At higher salt (greater than 150 mM KCl), the binding of TW 260/240 to actin was inhibited. The presence of skeletal muscle tropomyosin had no significant effect on the salt-dependent binding of TW 260/240 to F-actin.

Actins↗
PubMed1983

Actin filaments and vasopressin-stimulated water flow in toad urinary bladder.

Vasopressin increases the water permeability of the apical membrane of the granular epithelial cells of the toad urinary bladder. Cytochalasin B inhibits this action of the hormone, indicating that microfilaments may play a role in the water permeability response. We have extended previous functional studies with cytochalasin B and have demonstrated that dihydrocytochalasin B, a more specific inhibitor of actin filament elongation, similarly diminishes the hydrosmotic response to vasopressin. Biochemical studies of isolated epithelial cells indicate that an actin-like protein accounts for about 10% of the soluble protein of the epithelium. Morphological studies of whole toad bladders incubated with heavy meromyosin conclusively demonstrate that actin is a component of the epithelial cells and that actin-containing filaments are associated with both plasma membranes and cytoplasmic organelle membranes. Taken together, these findings provide strong, albeit indirect, evidence that actin microfilaments play a functional role in the hormone-induced increase in water permeability in the toad urinary bladder.

Actins↗
PubMed1980

Radiographic findings in congenital lead poisoning.

Because lead crosses the placenta throughout pregnancy, the fetus is at risk for lead poisoning. A full term, asymptomatic child was born with congenital lead poisoning secondary to maternal pica. Radiographic findings of a dense cranial vault, lead lines, and delayed skeletal and deciduous dental development were noted at birth. After chelation therapy, when the patient was seven months old, radiographs revealed normal skeletal maturation. Tooth eruption did not occur until 15 months of age. Newborn infants with these radiographic findings should be screened for subclinical, congenital lead poisoning.

Adolescent↗
PubMed1978

Cerebral echinococcosis, a pediatric disease: report of two cases with one successful five-year follow-up.

Two cases of cerebral echinococcosis in children emphasize the need to consider the Echinococcus in the differential diagnosis of children with CNS signs and symptoms. One patient died because of delay in seeking medical attention. The other is now a 22-year-old college student with no evidence of recurrence more than five years after removal of Echinococcus cysts from both brain and liver. The newer modalities available for diagnosis are discussed. Therapy with mebendazole is reviewed; this relatively new, highly effective anthelmintic is well tolerated and has been apparently highly effective in a small number of cases.

Adolescent↗
PubMed1977

Busulfan lung.

An uncommon, but lethal, toxic side effect of busulfan (Myleran) therapy for chronic myelogenous leukemia is pulmonary fibrosis. A 16-month-old male infant treated for 11 months with busulfan for chronic myelogenous leukemia is, we believe, the first case of "busulfan lung" in the pediatric age group to be reported. Progressive roentgenographic changes in the lung of a diffuse intra-alveolar and interstitial pattern were noted. The patient died after a four-day episode of cough, fever, and progressive dyspnea. At autopsy, no evidence of infection or leukemic infiltrates were seen in the lungs. Characteristic histologic findings as a result of busulfan therapy were observed in the lung and pancreas.

Busulfan↗