Random multiplicative processes and transport in structures with correlated spatial disorder.
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Journal Article↗
Biomedical subjects
M Schwartz
Publications and source records attributed to M Schwartz.
Search for new, long-lived, neutral particles.
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Journal Article↗
Potential difference responses to nutrient K+, Cl- and Na+ changes in secreting and resting states of frog stomach.
The effects of changes in nutrient concentrations of K+, Cl- and Na+ on the transmucosal potential difference (PD) and the resistance were compared for secreting fundus and resting fundus of Rana pipiens. Increase of K+ from 4 to 40 mM, decrease of Cl- from 81 to 8.1 mM and decrease of Na+ from 102 to 10 mM gave, 10 min after the change in the secreting fundus, delta PD values of -28.2, -19.8 and -7.5 mV, respectively. In the resting fundus with SCN- inhibition, the same changes in nutrient ion concentration gave delta PD values of -20.1, -17.0 and -10.2 mV, respectively. Changes in Na+ concentration were considered in a set of experiments of high acid secreting stomachs (4 to 6 mu equiv. . h-1 . cm-2). Here, delta PD gave for 10-fold decreases in Na+ concentration in secreting fundus -4.8 mV and in resting fundus with SCN- inhibition -22.6 mV. Omeprazole inhibition gave results quite similar to those with SCN- inhibition. From these results in going from secretion to inhibition, it follows that the increment of K+ conductance if it increased was lower than the increase in NaCl symport conductance since the change in delta PD for K+ decreased and that for Na+ increased. Also HCO3- conductance increased with inhibition. After SCN- inhibition the transmucosal resistance initially increased and later decreased. The decrease can be accounted for by the increase in conductance of the NaCl symport pathway and of the HCO3- pathway.
Animals↗
Shot-noise-generated 1/f fluctuations in one-dimensional systems.
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Journal Article↗
Prenatal diagnosis of cystic fibrosis using linked DNA probes.
This paper presents data collected in Europe on 107 prenatal diagnoses of cystic fibrosis (CF) using linked DNA markers. To date, 38 children have been born without CF, as predicted, demonstrating the present rapid move from research to clinical genetic service.
Adult↗
Regional localization of polymorphic DNA loci on the proximal long arm of the X chromosome using deletions associated with choroideremia.
In two unrelated families, males have been identified who suffer from choroideremia and at the same time have an interstitial deletion on the proximal long arm of the X chromosome. By high-resolution banding we have characterized the deletion chromosomes as del(X)(q21.1-q21.33) and del(X)(q21.2-q21.31) respectively. By Southern blot analysis we have mapped ten different polymorphic DNA loci relative to the position of the deletion and the choroideremia locus TCD. One probe, p31, was shown to cover one of the breakpoints of the smallest deletion. The following order of the loci was suggested by deletion mapping: cen-DXS106-DXS72-TCD-(DXYS1/DXYS23/DXYS5)- DXYS2-(DXYS12/DXS3)-(DXS17/DXS101)- Xqter.
Choroid↗
Investigation of three XX males by cytogenetic and DNA analyses. Suggestion of Y chromosome inversion polymorphism.
We report cytogenetic and DNA studies in three XX males. Two males seemed to have extra chromosomal material on the tip of one X chromosome. All three males were shown to have Y chromosome material as indicated by hybridization of Y-specific DNA probes to genomic DNA. One male was unusual in that as he showed the 15-kb fragment detected by pDP34 that is thought to map close to the Y centromere. It is suggested that this finding might point to an inversion on the Y chromosome.
Chromosome Inversion↗
Interstitial deletion of the short arm of chromosome 3. Fetal pathology and exclusion of the gene for beta-galactosidase-1 (GLB-1) from 3(p11----p14.2).
A de novo interstitial deletion of the short arm of chromosome 3 was prenatally diagnosed in a male fetus, karyotype 46,XY,del(3)(pter----p14.2::p11----qter). The fetus had craniofacial dysmorphisms, a single transverse palmar crease, ulnar deviation in the wrists, cardiovascular anomalies, a slight ureteric dilatation and a mobile caecum. Our observations are compared with five other cases with interstitial deletion of the short arm of chromosome 3 to delineate further the proximal 3p deletion syndrome. The gene for beta-galactosidase-1 (GLB-1) has previously been assigned to chromosome 3(p21----q21). The absence of a gene dosis effect for GLB-1 in this study indicates exclusion of GLB-1 from 3(p11----p14.2).
Abnormalities, Multiple↗
Effectiveness of neonatal transport in New York City in neonates less than 2500 grams--a population study.
In the past two decades, there has been a gradual trend to regionalization of perinatal care, categorization of hospitals and transport services for neonatal health care. The literature alludes to both beneficial and deleterious effects of neonatal transport (T) but no controls such as a matched nontransport (NT) population have been utilized to date. The major goal of this study was to evaluate the effect of neonatal transport from Level I and II high risk less than or equal to 2500 gm. neonates (born in NYC in one calendar year, 1979) compared to a cohort nontransported population matched for hospital of birth, weight, race, sex and risk. All transported less than or equal to 2500 gm. from Level I and II (n = 328) were studied and a stratified random sample of the nontransported (NT) infants less than or equal to 2500 gm. from these same hospitals (n = 2042) was used for comparison. The principle outcome variable was survival. The major conclusion of this study is that in Level I and II hospitals the transport group had a significantly increased survival in infants who were sick (Apgar less than 6) compared to cohorted nontransported controls. Interhospital differences in survival were noted among Level I and II but not seen in the subdivisions of (A) and (B) hospitals.
Demography↗
The effect of relaxin on calcium fluxes in the rat uterus.
Relaxin is a polypeptide hormone that inhibits rat uterine contractions. To test the hypothesis that the mechanism of action of this effect may involve shifts in calcium ions, the biologic action of relaxin on isolated rat uterine horns was directly correlated with measurements of 45Ca2+ efflux from and uptake into the tissues. Kinetic analysis demonstrated that the efflux of 45Ca2+ from rat uterine horns was significantly faster when tissue was incubated with 25 ng/ml relaxin as compared with control tissues incubated with no relaxin. In addition, at the end of the efflux experiments, control uteri contained 3.9% of the starting 45Ca2+, whereas the relaxin-treated uteri contained only 2.55%, indicating greater total Ca2+ efflux from the relaxin-treated horns (p less than 0.05). The effect of relaxin on 45Ca2+ uptake by uterine tissue was also studied. Analysis of uptake curves by linear regression demonstrated that relaxin treatment leads to less total uptake of 45Ca2+ in the uterine tissue, although the differences are not statistically significant. These experiments demonstrate that relaxin inhibition of rat uterine contractions in vitro is associated with a decrease in intracellular free Ca2+, caused, at least in part, by the promotion of Ca2+ efflux. These results represent the first step in defining the mechanism of action of this hormone.
Animals↗
Handedness, prenatal stress and pregnancy complications.
Two hundred and ninety children aged 2 yr were assessed for laterality on a number of preference and dexterity tasks. The mothers were interviewed about their child's pre- and perinatal history. Information was also obtained from hospital records about pregnancy and delivery stress and complications. High risk pregnancies or pregnancy complications were not associated with an increase in the proportion of sinistrality. Only one of the stress factors (low Apgar) was associated with a decrease in the strength of dexterity. Since maternal and hospital reports were not in agreement in reporting complications, the validity of data generated from maternal reports is questioned.
Child, Preschool↗
Interactions between human and carp (Cyprimus carpio) low density lipoproteins (LDL) and LDL receptors.
1. We have compared the concentration and chemical composition of carp and human plasma lipoproteins and studied their interaction with human fibroblast LDL receptors. 2. The main lipoproteins in carp are of high density (HDL) in contrast to low density lipoproteins (LDL) in human. 3. Carp lipoproteins are devoid of apolipoprotein (apo) E, a major ligand for interaction with LDL receptors in mammals. 4. Carp very low density lipoproteins (VLDL) and LDL but not HDL nor apoA-I cross react with human LDL in their interaction with LDL receptors on human cultured fibroblasts. 5. Carp liver membranes possess high affinity receptors that are saturable and have calcium dependent ligand specificity (apoB and apoE) similar to human LDL receptor. Carp VLDL and LDL but not HDL nor its major apolipoprotein complexed to L-alpha-phosphatidylcholine dimyristoyl (apoA-I-DMPC) competed with the specific binding of human LDL to this receptor.
Adult↗
Treatment of ischemia due to "steal" by arteriovenous fistula with distal artery ligation and revascularization.
Three cases are described of upper extremity ischemia occurring after the creation of fistulas (AVFs) (one case) and bridge AVFs (two cases) for hemodialysis access. All three cases were successfully treated with ligation of the artery immediately distal to the origin of the AVF in conjunction with a reversed saphenous vein bypass. The latter was constructed from the artery proximal to the origin of the fistula to the artery distal to the site of ligation. Preoperative and postoperative hemodynamic measurements and complete disappearance of symptoms indicated that this procedure corrected the ischemic steal phenomenon. Angioaccess function was not affected in these three cases, thereby allowing continuation of its use immediately after corrective surgery and for follow-up periods of 1 month, 6 months, and 8 years.
Adult↗
Type-specific antibodies to herpes simplex virus type 2 (HSV-2) glycoprotein G in pregnant women, infants exposed to maternal HSV-2 infection at delivery, and infants with neonatal herpes.
We used a murine monoclonal antibody to herpes simplex virus (HSV) type 2 (HSV-2) glycoprotein G (gG) to develop an enzyme immunoassay that detected HSV-2 type-specific antibodies in human sera. Antibodies to HSV-2 gG were detected in 98 (96%) of 102 sera from pregnant women with culture-proved HSV-2 infection. Sixty-five percent of the women had serological evidence of past HSV-2 infection by the Rawls index, based on titers of neutralizing antibody to HSV type 1 and HSV-2. Thirty (88%) of 34 infants exposed to maternal HSV infection at delivery had antibodies to HSV-2 gG and remained well. One infant exposed to primary maternal HSV-2 infection lacked antibodies to HSV-2 gG and developed neonatal HSV-2 infection. The mean +/- SD optical density by HSV-2 gG enzyme-linked immunosorbent assay for sera obtained from 17 infants within one week after onset of neonatal HSV-2 infection was 0.25 +/- 0.12, compared with 1.15 +/- 0.34 in cord blood sera from exposed infants who did not develop symptoms (P less than .0001 by t test).
Antibodies, Viral↗
Decompression and circumferential stabilization of unstable spinal fractures.
A technique of anterior decompression of the spinal canal with anterior strut grafts, followed by posterior instrumentation and local fusion, is described in a group of 18 patients with unstable thoracolumbar fractures. All patients were found to have greater than 50% encroachment of the spinal canal and a preoperative kyphosis of 21.8 degrees. At follow-up 81% of patients with incomplete neurological lesions improved at least one Frankel Grade. Residual encroachment on the spinal canal was 4.6% and at follow-up the kyphotic angle was 17.1 degrees. Complications included one anterior graft loosening (not requiring revision), three loosened rods, only one of which required revision, and one fractured Harrington rod which did not require revision. The authors conclude that this technique is an effective and safe method for treating unstable thoracolumbar injuries and is recommended if anterior instrumentation is unavailable.
Adult↗
Esmolol: safety and efficacy in postoperative cardiothoracic patients with supraventricular tachyarrhythmias.
Esmolol, an intravenous, ultrashort-acting beta-blocker, was studied for its ability to safely control supraventricular arrhythmias up to 24 hours in 15 postoperative cardiothoracic surgery patients with atrial fibrillation or flutter and rapid ventricular response. Esmolol obtained an initial therapeutic response in nine (60 percent) patients. Mean heart rate for the 15 patients was reduced from 139 +/- 12 beats/min before therapy to 106 +/- 21 beats/min during esmolol infusion (p less than 0.01). The mean time to a therapeutic response after initiation of therapy, using a multistep titration regimen (500 micrograms/kg/min loading infusions over one minute, prior to incremental titration steps from 50 to 300 micrograms/kg/min over 4 to 14 minutes), was 22 +/- 9 minutes, and therapy was continued for 17 +/- 9 hours in responders. Esmolol significantly lowered blood pressure in the group studied and resulted in mild supine or orthostatic hypotension in ten (67 percent) patients. Side effects, including hypotension (10/15 patients), gastrointestinal disturbances (2/15), and weakness or somnolence (6/15), were transient and were not associated with serious clinical sequelae. We conclude that esmolol is effective for rate control in a majority of postoperative cardiothoracic surgery patients with atrial fibrillation or flutter. Side effects, although mild, occur relatively frequently, limiting prolonged infusions and warranting close surveillance of patients.
Adrenergic beta-Antagonists↗
Effect of amphotericin B and tear K+ on PD responses to changes in stromal K+ in frog cornea.
Data have been presented in this paper that support the hypothesis that normal or anomalous responses to changes in stromal K+ are a result of the relative conductances of the simple K+ and the (Na+ + K+)-ATPase pathways located in the basolateral membrane of the corneal epithelium. The simple K+ conductance may be changed by changing the tear K+ concentration in the presence of amphotericin B and by the use of Ba2+ in the stromal solution.
Amphotericin B↗
Hereditary X-linked thrombocytopenia maps to the same chromosomal region as the Wiskott-Aldrich syndrome.
Hereditary X-linked thrombocytopenia occurs either as isolated thrombocytopenia or as a part of the Wiskott-Aldrich syndrome (WAS). We studied X-linked thrombocytopenia in a family with eight affected male members, none of whom exhibited the increased susceptibility to infection that occurs in WAS. We found a significant linkage between thrombocytopenia and DXS 146, a marker on the proximal part of the short arm of the X-chromosome. WAS has previously been mapped to the same chromosomal region. The present findings indicate that X-linked thrombocytopenia and WAS are closely related and may even be caused by different mutations of the same gene. This view is supported by our findings of atopic symptoms and minor deviations in immunologic variables among some of the affected subjects.
Adolescent↗