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Biomedical subjects

M Marks

Publications and source records attributed to M Marks.

At least 55 records · Page 3Linked to original sources
PubMed1992

Tissue compatibility of tyrosine-derived polycarbonates and polyiminocarbonates: an initial evaluation.

Compression-molded disks of two tyrosine-derived polymers [poly(desaminotyrosyl-tyrosine-hexyl ester carbonate) and poly(desaminotyrosyl-tyrosine hexyl ester iminocarbonate)], two polymers derived from Bisphenol A [poly(Bisphenol A iminocarbonate) and poly(Bisphenol A N-phenyliminocarbonate)], and two clinically used standard materials [poly(D,L-lactic acid) and high-density polyethylene] were implanted subcutaneously in the back of Sprague-Dawley rats. The tissue response elicited by these materials was evaluated histologically at 7, 30, and 120 days postimplantation, based on the total cell density (including fibroblasts, monocytes, giant cells, and macrophages) at the implantation site. The tissue response observed for the two tyrosine-derived polymers was mild, comparable to the two standard materials, medical-grade poly(L-lactic acid) and high density polyethylene. The two Bisphenol A-containing polymers elicited significantly more severe tissue responses. These results indicate that the use of derivatives of the natural amino acid L-tyrosine in the synthesis of degradable implant materials improved the tissue compatibility of these materials relative to chemically related polymers that contain Bisphenol A, an industrial diphenol. The tyrosine-derived polyiminocarbonate and polycarbonate are therefore promising candidates for a detailed evaluation of their biocompatibility, including long-term implantation studies in higher mammals.

Animals↗
PubMed1992

Acute colonic diverticular perforation presenting as left ear pain and facial swelling due to cervical subcutaneous emphysema in a patient administered corticosteroids.

A 56-yr-old white female administered corticosteroids presented with left ear pain and facial swelling due to cervical subcutaneous emphysema from a diverticular perforation of the sigmoid colon. This case demonstrates that localized signs of a bowel perforation may be absent in patients administered corticosteroids, that these patients may present with unusual, remote findings, and that bowel perforation can produce cervical subcutaneous emphysema.

Acute Disease↗
PubMed1990

Polyneuropathy, ophthalmoplegia, leukoencephalopathy, and intestinal pseudo-obstruction: POLIP syndrome.

We describe 5 individuals (from three separate families) with a progressive neurological disorder characterized by sensorimotor peripheral polyneuropathy, cranial neuropathies (external ophthalmoplegia, deafness), and the syndrome of chronic intestinal pseudo-obstruction. Magnetic resonance imaging showed widespread abnormality of the cerebral and cerebellar white matter in the 2 patients studied. Autopsy examination in 3 revealed widespread endoneurial fibrosis and demyelination in the peripheral nervous system, possibly secondary to axonal atrophy, and poorly defined changes in cerebral white matter (leukoencephalopathy). The cranial nerves and spinal roots were less severely involved and the neurons in the brainstem and spinal cord were intact. The fatal gastrointestinal dysmotility was due to a severe visceral neuropathy. We suggest that these patients manifested a hereditary disorder with distinctive clinical, radiological, and neuropathological features, and propose the acronym POLIP to emphasize the distinctive tetrad of polyneuropathy, ophthalmoplegia, leukoencephalopathy, and intestinal pseudo-obstruction.

Adult↗
PubMed1990

Wd(a+) red blood cells in two sisters of a Hei//om Khoisan family in Namibia.

Two sisters in a Hei//om family of the southern African Khoisan race in Namibia were found to have Wd(a+) red blood cells. Wda is a low-frequency antigen identified so far only in a European family in Canada and a family in Holland. The Wda gene may have had an independent origin in the Khoisan. Alternatively, the Hei//om population may have acquired it through miscegenation.

Blood Group Antigens↗
PubMed1988

Hepatobiliary scintigraphy in arteriohepatic dysplasia (Alagille's syndrome). A report of two cases.

Hepatobiliary scintigraphy has proven to be of great utility in distinguishing biliary atresia from other causes of neonatal cholestasis. Arteriohepatic dysplasia (Alagille's syndrome) is an uncommon entity characterized by typical facial features, pulmonary artery stenosis, and a liver disorder which presents during the neonatal period as progressive jaundice. Two neonates, who were later shown to have Alagille's syndrome, underwent hepatobiliary scintigraphy to rule out biliary atresia. Findings on the hepatobiliary scans from the two patients were similar to those usually associated with biliary atresia and both finally required surgical exploration to rule out biliary atresia. The findings on hepatobiliary scans in these patients with Alagille's syndrome are discussed and compared with those associated with other forms of neonatal cholestasis.

Bile Ducts, Intrahepatic↗
PubMed1988

Sputum changes associated with therapy for endobronchial exacerbation in cystic fibrosis.

We sought to define objective indicators of the resolution of Pseudomonas aeruginosa endobronchial infection in patients with cystic fibrosis. We prospectively studied 75 patients admitted for treatment of a pulmonary exacerbation and quantitated sputum bacterial density, DNA content, and the concentration of albumin and total protein in sputum, and compared these values with clinical evaluation. Eleven of the 75 patients had systemic signs, fever, and leukocytosis, which we arbitrarily defined as due to endobronchial infection. At the end of hospitalization, these 11 patients were afebrile, had peripheral leukocyte counts in the normal range, and were judged improved. Sputum P. aeruginosa density, DNA content, and total protein content on admission were similar in the two illness groups. Hospitalization and parenteral antibiotic administration for an average of 14.6 days were associated with improved pulmonary function in all 75 subjects (P values for forced vital capacity, forced expiratory volume at 1 second, and peak expiratory flow rate were all less than 0.001). With improvement, there was a decrease in sputum P. aeruginosa density (mean of both groups decreased from 10(7.80) CFU/g on admission to 10(5.96) CFU/g; P less than 0.001), and a decreased DNA concentration (overall mean 4.73 +/- 4.75 on admission to 2.76 +/- 2.49 mg/g; P less than 0.002). The decrease in sputum total protein concentration for both groups was not significant (overall mean 60.5 +/- 48.4 to 43.9 +/- 38.2 mg/g; P = 0.06). Sputum albumin concentrations did not change in either group. We conclude that in cystic fibrosis subjects with a pulmonary exacerbation, bacterial density, sputum DNA and protein content decrease with hospitalization and parenteral antibiotic therapy. At the end of treatment, these indices of sputum infection and inflammation correlate with improved pulmonary function and clinical improvement. These changes are independent of the presence or absence of fever on admission.

Adolescent↗
PubMed1988

Sleep and circadian rhythms of temperature and urinary excretion on a 22.8 hr "day".

Two groups of subjects (total N = 6) were studied in an isolation chamber for a period of 3 weeks whilst living on a 22.8 hr "day". Regular samples of urine were taken when the subjects were awake, deep body temperature was recorded continuously and polygraphic EEG recordings were made of alternate sleeps. The excretion in the urine of potassium, sodium, phosphate, calcium and a metabolite of melatonin were estimated. Measurements of the quantity and quality of sleep were made together with assessments of the temperature profiles associated with sleep. In addition, cosinor analysis of circadian rhythmicity in urinary variables and temperature was performed. The 22.8 hr "days" affected variables and subjects differently. These differences were interpreted as indicating that the endogenous component of half the subjects adjusted to the 22.8 hr "days" but that, for the other three, adjustment did not occur. When the behaviour of different variables was considered then some (including urinary potassium and melatonin, sleep length and REM sleep) appeared to possess a larger endogenous component than others (for example, urinary sodium, phosphate and calcium), with rectal temperature behaving in an intermediate manner. In addition, a comparison between different rhythms in any subject enabled inferences to be drawn regarding any links (or lack of them) that might exist between the rhythms. In this respect also, there was a considerable range in the results and no links between any of the rhythms appeared to exist in the group of subjects as a whole. Two further groups (total N = 8) were treated similarly except that the chamber clock ran at the correct rate. In these subjects, circadian rhythms of urinary excretion and deep body temperature (sleep stages and urinary melatonin were not measured) gave no evidence for deterioration. We conclude, therefore, that the results on the 22.8 hr "day" were directly due to the abnormal "day" length rather than to a prolonged stay in the isolation chamber.

Adolescent↗
PubMed1987

Nephropathic cystinosis with central nervous system involvement.

Nephropathic cystinosis is associated with end-stage renal failure, retinal damage, and hypothyroidism. Patients may now survive past the first decade of life with the use of dialysis and renal transplantation. Examination of a 24-year-old woman with this disorder revealed ovarian failure, mildly abnormal results on a glucose tolerance test, intermittent confusion, short-term memory loss, and cerebral atrophy on computerized axial tomography. Autopsy examination at age 25 years revealed cystine storage in multiple tissues including the atrophic ovaries, pancreatic islet cells, the aorta, and the brain. Dysfunction of multiple organ systems may develop in patients with cystinosis who survive into adulthood. This emphasizes the need for a systemic therapy for cystinosis.

Adult↗
PubMed1986

Clinical pharmacology of vinzolidine.

Vinzolidine (VZL), a new semisynthetic vinca alkaloid, was studied by using 3H-labeled VZL administered PO in four patients. At single doses from 1.5 to 36.5 mg/m2 (0.034-0.919 mg/kg) radioactivity was rapidly absorbed with a half-life of absorption of 1 h and a peak at 4 h. Plasma decay of radiolabel followed a biphasic pattern with an alpha half-life of 10.48 h and a beta half-life of 172 h. The apparent plasma clearance was dose-dependent. The total radiolabel recovered was 52.9% +/- 11.4% of the administered label, with 90% in the feces. HPLC analysis revealed that in all extracted plasma, urine, and feces the predominant material was unchanged VZL. Several metabolites were observed but not identified.

Dose-Response Relationship, Drug↗
PubMed1985

Refinements in reconstruction of congenital breast deformities.

The use of tissue-expansion prostheses offers significant advantages in the reconstruction of congenital breast deformities, including Poland's syndrome. In the patient who has completed normal breast development, expansion on the abnormal side allows the development of adequate overlying skin and enlargement of the nipple-areola complex. It further allows transposition of the nipple-areola complex to a more normal location. In young patients who have not completed full breast development, tissue expanders have been placed beneath the hypoplastic breast and remain in place for many years. Periodic inflation of saline allows symmetry to be maintained as the opposite breast matures.

Adolescent↗
PubMed1985

Small bowel trauma in children and adolescents.

Fifty-five children and adolescents with blunt and penetrating small bowel injuries were treated during a 17-year period. Fourteen patients had blunt injuries, and there were no deaths in this group. The remaining 41 patients had penetrating small bowel injuries, with a mortality of 10 per cent. A decision to operate based on physical examination can be made in the pediatric age group without unduly delaying operation or increasing mortality.

Abdominal Injuries↗
PubMed1983

Hyperbaric-oxygen treatment of multiple sclerosis. A randomized, placebo-controlled, double-blind study.

Several uncontrolled studies have suggested a beneficial effect of hyperbaric oxygen on multiple sclerosis. We studied 40 patients with advanced chronic multiple sclerosis who were randomly divided into two matching groups. The experimental group received pure oxygen, and the placebo group received a mixture of 10 per cent oxygen and 90 per cent nitrogen; both groups were treated at a pressure of 2 atmospheres absolute for 90 minutes once daily, for a total of 20 exposures. Objective improvement occurred in 12 of 17 patients treated with hyperbaric oxygen and in 1 of 20 patients treated with placebo (P less than 0.0001). Improvement was transient in seven of the patients treated with oxygen and long-lasting in five. Those with less severe forms of the disease had a more favorable and lasting response. At one year of follow-up, deterioration was noticed in 2 patients (12 per cent) in the oxygen group, neither of whom had had an initial response, and in 11 patients (55 per cent) in the placebo group, one of whom had had a positive initial response (P less than 0.0008). Minor ear problems and reversible myopia were the only side effects observed. These preliminary results suggest a positive, though transient, effect of hyperbaric oxygen on advanced multiple sclerosis, warranting further study. This therapy cannot be generally recommended without longer follow-up periods and additional confirmatory experience.

Adult↗
PubMed1979

Urinary hexosaminidase in patients with lung carcinoma.

The specific activity of urinary hexosaminidase was determined in 58 patients with various histological types of lung carcinoma. Compared to an apparently healthy control population, 32/35 patients with widely disseminated disease showed elevated values and 18/23 patients with disease confined to the chest had normal hexosaminidase values. Detailed studies of 18 patients indicated that declining hexosaminidase values were associated with effective therapy, rising values generally accompanied progressive disease.

Adenocarcinoma↗