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Biomedical subjects

M McLaughlin

Publications and source records attributed to M McLaughlin.

At least 19 recordsLinked to original sources
PubMed1992

Which newborns in New York City are at risk for special education placement?

In this study of 162 third graders in New York City public schools, we found that slightly over half of the children in special education were males who had Medicaid coverage at birth and mothers with medical conditions or adverse health habits noted on the birth certificate; two thirds of the children with this combination of characteristics actually were placed in special education. These findings suggest that newborns at risk for later learning disabilities can be targeted to receive preventive interventions.

Birth Certificates↗
PubMed1991

Robustness of G proteins in Alzheimer's disease: an immunoblot study.

Many of the neurotransmitter systems that are altered in senile dementia of the Alzheimer type are known to mediate their effects via G proteins, yet the integrity of guanine nucleotide-binding proteins (G proteins) in Alzheimer's diseased brains has received minimal investigation. The aim of this study was to establish whether the level of G alpha subunits of five G proteins was altered in Alzheimer's disease. We used immunoblotting (Western blotting) to compare the amounts of Gi1, Gi2, GsH (heavy molecular weight), GsL (light molecular weight), and Go in the frontal cortex and hippocampus, two regions severely affected by the disease, and the cerebellum, which is less severely affected. The number of senile plaques was also quantified. We report that there was no significant difference in the level of these G alpha subunits between Alzheimer's diseased and age-matched postmortem brains. These results suggest that alterations in the amount of G protein alpha subunits are not a feature of Alzheimer's disease.

Alzheimer Disease↗
PubMed1991

Expression in non-lens tissues of an enzyme activity related to the 'lens-specific' protein, delta crystallin.

When chick embryo neutral retina (NR) cells are cultured for long periods in vitro, they undergo extensive transdifferentiation into lens and express the lens protein, delta crystallin. We now demonstrate that this process is accompanied by a change in the chromatin conformation of the delta-gene locus from DNAase1-resistant to DNAase1-sensitive in the nuclei of most cells. Transcripts hybridising to a delta probe are also much more prevalent among the in vitro transcription products from lens or transdifferentiated NR culture nuclei, as compared to nuclei from fresh NR tissue. Published evidence indicates that the chick delta 1 crystallin gene encodes the major structural protein of embryonic lens fibres, whereas the closely related delta 2 gene may encode the urea-cycle enzyme argininosuccinate lyase (ASL). Our present data lends further support to this view. Both immunodetectable delta-related protein(s) and ASL activity are present in fresh embryonic NR tissue, as well as in mouse and Rana liver, and in Rana lens. Our polyclonal anti-delta antibody also cross-reacts with a major constituent of commercial bovine ASL, of the same molecular size as chick delta crystallin. Immunoselection studies suggest that the ASL activity in chick embryonic NR is conferred mainly by the delta-related protein band. So-called 'ectopic' expression of delta crystallin in embryonic NR (and other tissues) may thus involve the delta 2/ASL gene, and could reflect some metabolic requirement for ASL activity.

Animals↗
PubMed1990

Basal and haloperidol-stimulated prolactin in neuroleptic-free men with schizophrenia defined by 11 diagnostic systems.

Forty-four male, neuroleptic-free, acutely psychotic patients with at least one diagnosis of schizophrenia among 11 diagnostic systems, and 28 healthy controls, underwent measurement of prolactin (PRL) concentrations before and after intravenous administration of haloperidol (0.5 mg). Basal PRL concentrations were lower in the patients with Research Diagnostic Criteria (RDC) DSM-III, Cloninger, and Taylor and Abrams schizophrenias than in controls. Compared with the controls, the PRL response to haloperidol was lower in the patients with schizophrenia defined by all diagnostic systems except those of Schneider and M. Bleuler. Neither basal nor stimulated PRL concentrations were correlated with positive symptoms, but basal PRL was correlated with the Brief Psychiatric Rating Scale (BPRS) depression-related subscore. This study lends further support for the presence of dopaminergic dysfunction in schizophrenia, and demonstrates the advantages and problems in the use of multidiagnostic psychopathological evaluation to categorize a disorder where there is major disagreement among diagnostic systems.

Acute Disease↗
PubMed1990

Effect of 2-amino-7-phosphonoheptanoic acid (APH) on seizure susceptibility in the prepubescent and mature rat.

There is now considerable evidence that the N-methyl-D-aspartic acid receptor is important in the genesis of seizures. One of the selective antagonist of the NMDA receptor is 2-amino-7-phosphonoheptanoic acid (APH). In this study we evaluated the effects of intracerebroventricular (i.c.v.) administration of APH on seizure susceptibility in both prepubescent and mature rats using the rapid kindling and flurothyl ether seizure models. Both the immature and mature animals receiving APH kindled at a significantly slower rate than control animals receiving phosphate-buffered saline. APH also demonstrated a significant anticonvulsant effect against flurothyl-induced seizures in both the immature and mature animals. This study supports prior work that selective NMDA receptor antagonists such as APH may have promise as potential antiepileptic agents.

2-Amino-5-phosphonovalerate↗
PubMed1990

Inhibitory influence of phosphate and arsenate on contraction of skinned skeletal and cardiac muscle.

It has been widely observed that Pi decreases maximum calcium-activated force (Fmax) and calcium sensitivity of skinned skeletal and cardiac muscle. However, whether a particular ionic species of Pi (i.e., H2PO4-) is responsible for these effects is controversial. To clarify this issue, we examined the influence of Pi and its structural analogue arsenate (Asi) on contraction of skinned rabbit psoas (fast twitch), soleus (slow twitch), and cardiac papillary muscle. Asi decreased Fmax of all three muscles types to a greater extent than Pi. Both Pi and Asi decreased calcium sensitivity of psoas and cardiac muscles, with Asi having the greater effect. The effect of the protonated form of Pi and Asi on Fmax was evaluated by measuring the response to 30 mM total Pi or Asi at pH 7.4, 7.0, 6.6, and 6.2. In psoas fibers we found that both Pi and Asi were more effective in decreasing Fmax as the pH was lowered (i.e., as the concentration of the diprotonated forms increased). On the contrary, soleus and cardiac fibers did not exhibit this behavior. These differences in the effects of Pi and Asi on Fmax in psoas vs. cardiac and soleus muscles may be related to differences in their myosin heavy chains other than the binding site for the gamma-phosphate of ATP which appears to be conserved for all myosins.

Animals↗
PubMed1989

Nuclear factors from expressing tissues interact in vitro with a rat alpha-2u globulin gene intron.

Members of the rat alpha 2u globulin gene family are expressed in a tissue-specific manner. Using a DNase I footprinting assay, we find that expressing tissues (liver, lachrymal, and salivary gland) contain nuclear proteins that interact specifically with two sites in the third intron of a cloned gene. These sequences are similar to a CCAAT-like sequence in the 5'-flanking region of the gene and the binding site for the transcription factor Sp1. Extracts of nonexpressing tissues (kidney, testis, brain, and spleen) do not show footprinting activity at these sites. Whereas hepatic expression of alpha 2u globulin is restricted to normal adult males, nuclear extracts of liver from all animals (adult and juvenile, male and female, intact and hypophysectomized) produce similar footprints. Footprints by extracts of lachrymal and salivary glands, tissues that express a subset of alpha 2u globulin genes distinct from the hepatic set, are also similar to the liver activity. The findings suggest that the third intron of an alpha 2u globulin gene contains sites that interact with tissue-specific factors to establish the potential for hormonal and developmental control of expression.

Alpha-Globulins↗
PubMed1978

Monomethylformamide levels in human urine after repetitive exposure to dimethylformamide vapor.

Eight healthy male subjects were exposed to DMF vapor at a concentration of 8.79 +/- 0.33 ppm for six hours daily for five consecutive days. All urine voided by the subjects was collected from the beginning of the first exposure to 24 hours past the end of the last exposure and each sample was analyzed for monomethylformamide (MMF). MMF was rapidly eliminated from the body with urine values peaking within a few hours following the end of each exposure period. Very little was found in the 24-hour postexposure sample and none was found in a 48-hour postexposure sample. There was no increased excretion of MMF in the urine following repetitive exposure. The mean for the seven-hour (end of exposure) sample was 4.74 microgram/ml or 736.8 microgram. Lower and upper one-sided 95% tolerance limits for 95% of the population were 1.2 microgram/ml (367 microgram) and 13.9 microgram/ml (1625 microgram). The coefficient of variation (CV) for microgram MMF/ml was approximately 25 times more variable than the CV for total microgram.

Adult↗
PubMed1978

Cation and hydrogen ion effect on canine acid and gastrin output.

Differential stimulating effects on the parietal cell of dogs by calcium, magnesium and sodium were noted only at an alkaline pH. Acid inhibited the parietal cell, and antral perfusion did not cause gastrin stimulation at any pH level. The pH of the milieu of the parietal cell appears to be a more critical regulator of acid secretion than physiologic antral gastrin variation.

Animals↗
PubMed1976

Human gastrin response to secretin after vagotomy.

The gastrin response to a liquid meal with and without secretin infusion was studied in nine patients undergoing selective or truncal vagotomy with pyloroplasty for duodenal ulcer disease. Fasting gastrin levels were significantly increased in eight of nine patients after vagotomy, but secretin infusion did not consistently suppress these basal gastrin levels either pre- or postoperatively. Infusion of secretin did significantly lower the integrated gastrin response to feeding both pre- and postoperatively in eight of nine patients. Vagotomy alone did not significantly alter the integrated gastrin response to feeding. This data gives evidence that secretin infusion remains a helpful diagnostic test, differentiating those patients with recurrent ulcer and elevated gastrin levels postvagotomy from those patients with occult Zollinger-Ellison syndrome.

Calcium↗
PubMed1976

Effects of hypercapnia on uterine and umbilical circulations in conscious pregnant sheep.

Changes in the uterine and umbilical circulations during induced hypercapnia were studied in nine unanesthetized near-term pregnant sheep. Blood flows were measured with electromagnetic flow transducers and arterial pressures with vascular catheters implanted under anesthesia 2-16 days prior to experiments. Hypercapnia was induced in the fetus alone by giving acetazolamide iv to the fetus, 100-200 mg/kg. Mean fetal arterial Pco2 increased from 49.5 to 63.4 mmHg but no significant changes in umbilical blood flow occurred. Stepwise increases in both maternal and fetal arterial Pco2 were induced by increasing maternal inspired CO2 concentration to a maximum of 12%. No dignificant changes occurred in uterine or umbilical circulations until hypercapnia was severe (maternal arterial Pco2 greater than 60 mmHg, fetal arterial Pco2 greater than 70 mmHg). With severe hypercapnia uterine vascular resistance increased significantly and uterine blood flow decreased despite an increase in maternal arterial pressure; fetal arterial pressure and umbilical blood flow increased significantly, but umbilical vascular resistance did not. We conclude that hypercapnia in conscious pregnant sheep is associated with significant changes in uterine and umbilical circulations, but only when hypercapnia is severe. Carbon dioxide is unlikely to be a factor in normal physiological regulation of the uteroplacental circulation in this species.

Acetazolamide↗