Biomedical subjects

M Shields

Publications and source records attributed to M Shields.

34 records · Page 2Linked to original sources

PubMed1985

Lead-induced activation and inhibition of potassium-selective channels in the human red blood cell.

The selective increase of net K+ permeability in human red cells brought about by either Ca2+ or lead was studied using a light scattering technique to measure net K+ fluxes in cell suspensions and the patch-clamp technique to study K+ transport in individual K+-selective channels of the red cell membrane. Using ultrapure solutions it was demonstrated that the effect of lead is neither the indirect consequence of a lead-induced increase of the accessibility of the receptor sites of the K+-selective channels to traces of Ca2+ that are present as contamination in analytical grade reagents nor to the release of Ca2+ from intracellular Ca2+ stores. It is further shown that in cell-free membrane patches low concentrations of lead (10 microM) in Suprapur solutions evoke the same single-channel events as added Ca2+ and that this activity can be inhibited by high concentrations of lead (100 microM), similar to the net KCl efflux measured by means of the light scattering technique. It is concluded, therefore, that both Ca2+ and lead independently activate the same K+-selective channels in the red cell membrane.

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

PubMed1985

Open letter to women who have ever used an IUD.

Explore the source record for details and available documents.

Female↗

PubMed1985

Subarachnoid space: middle ear pathways and recurrent meningitis.

Congenital bony abnormalities of the inner ear may result in a communication between the middle ear and the subarachnoid space. Patients with this anomaly often present with recurrent meningitis associated with acute otitis media or with middle ear fluid. This article presents three cases of recurrent meningitis with open middle ear--subarachnoid space connections. The first two cases involve a cerebrospinal fluid leak into the middle ear via the oval window, both patients having a Mondini-type of inner ear deformity. The pathway in the third case opened into the middle ear along the horizontal portion of the facial nerve. Computed tomography (CT) scanning with metrizamide and differential density calculations helped to identify the abnormal pathway and to confirm that the leak has been closed postoperatively. Use of the CT scanner in these cases can be helpful in planning the surgical closure and in postoperative follow-up.

Adolescent↗

PubMed1983

The association between prolyl hydroxylase metabolism and cell growth in cultured L-929 fibroblasts.

Prolyl 4-hydroxylase (EC 1.14.11.2) is a key enzyme in collagen biosynthesis, its active form is a tetramer (alpha 2 beta 2). In L-929 fibroblasts in the log phase of culture there is a low level of active enzyme. When the cell culture reaches confluency, prolyl hydroxylase activity in cells increases by a process that requires de novo RNA and protein synthesis. The same result may be achieved by crowding the cells (replating log phase cells at the density of stationary phase cells). In the work reported here we further examined induction of the enzyme. RNA synthesis necessary for enzyme induction is complete 6 h after "crowding" while protein synthesis requires 12 h. Thymidine (0.2-0.5 mM) added to log phase cells will also cause enzyme induction to the level found in "crowded" or resting cells. We also looked at the decay of the enzyme activity after subculture. This occurs rapidly (enzyme half-life is 1-2 h) and is concurrent with the re-entry of resting cells into cell cycle; however, thymidine added at the time of subculture to block DNA synthesis does not prevent the loss of prolyl hydroxylase activity. These results suggest that when cells are not engaged in propagation, they begin to synthesize luxury proteins such as prolyl hydroxylase. However, the loss of prolyl hydroxylase during subculture is probably not a direct consequence of DNA synthesis.

Animals↗

PubMed1983

Neuroblastoma associated with Beckwith-Wiedemann syndrome.

This report describes an infant with Beckwith-Wiedemann Syndrome (BWS) found to have a thoracic neuroblastoma. Infants with BWS are known to have an increased incidence of tumors (10%). We believe this to be the first report of a malignant neural crest tumor in a child with BWS and also the first case occurring in familial BWS. Usually the malignancies associated with the BWS are intraabdominal; however, this malignancy was located in the chest. It is important to detect malignancy in early stages. Therefore, recommendations for screening children with BWS are discussed.

Beckwith-Wiedemann Syndrome↗

PubMed1982

Evaluation of a detoxification regimen for fat stored xenobiotics.

A detoxification regimen has been found to be safe for use by individuals exposed to recreational (abused) and medical drugs, patent medicines, occupational and environmental chemicals. Patients with high blood pressure had a mean reduction of 30.8 mm systolic, 23.3 mm diastolic. Cholesterol level mean reduction was 19.5 mg/100ml, while triglycerides did not change. Medical complications associated with the program were rare, occurring in less than three percent of the subjects. The program resulted in improvements in psychological test scores. The mean increase in Wechsler Adult Intelligence Scale IQ was 6.7 points. High Minnesota Multiphasic Personality Inventory profiles decreased on the third scale (10.7), the fourth scale (8.0), the fifth scale (4.5) and the sixth scale (8.0). The decrease in the fourth scale suggests hope for sociopaths, a group with fourth scale scores not improved by National Institute for Mental Health or Narcotic Addict Rehabilitation Act inpatient programs.

Adipose Tissue↗

PubMed1980