Search PubMed⌕ Search

Biomedical subjects

L J Martin

Publications and source records attributed to L J Martin.

At least 181 records · Page 10Linked to original sources
PubMed1984

Cytophotometric analyses of brain neuronal RNA in soman intoxicated rabbits.

Quantitative azure B-RNA cytophotometry was used to monitor metabolic responses of individual neurons of the motor cortex (layer V) and caudate nucleus of soman (pinacolyl methylphosphonofluoridate) poisoned rabbits. Time- and dose-dependent RNA responses were related to the extent of acetylcholinesterase (AChE) inactivation of these 2 brain regions and to overt behavioral manifestations of toxication. A complex pattern of RNA responses was evidenced, with RNA depletion occurring at both arousal and convulsive doses of soman. In general, RNA changes paralleled previously reported metabolic responses observed in soman toxicated rats and mice: (1) linear dose-dependent suppression of RNA was evidenced during the depressant phase but not in the acute excitatory phase of toxication; and (2) RNA depletion was more severe following than during the appearance of excitatory symptoms. These data indicate that soman poisoning results in metabolic correlates of impaired rather than excessive CNS activation. It is postulated that metabolic disturbances are related to blockade of central cholinergic excitation, and that disruption of functionally integrated synaptic activity forms a critically important aspect of toxication.

Acetylcholinesterase↗
PubMed1982

A study of radiation parameters in an open-pit mine.

Radiation parameters associated with the open pit mining of a small (10,000 tonnes), but high grade (2%) uranium deposit at Nabarlek, N.T., have been investigated in detail. External radiation levels, radon emanation rates and radon daughter levels were measured systematically during the development of the mine, and are correlated with ore grade, properties of the host rock and atmospheric conditions. Significant radon daughter concentrations were observed only under stable atmospheric conditions, usually during the might and were invariably associated with thermal inversions. The mean cumulative exposure to radon daughters was estimated from the measured levels to be 0.065 Working Level Months for employees working in the pit for the entire four and a half months of mining. The mean cumulative external gamma ray exposure for the same employee group was measured using thermoluminescent dosimeters to be 2.3 mSv (230 mrem). For most other employees, however, exposures were much lower. Data on long lived radionuclides in dust and on particle size distribution are also presented.

Air Pollution, Radioactive↗
PubMed1981

Intraocular endoscopic surgery.

We have successfully used a new small endoscope in posterior segment surgery in situations where the operating microscope or binocular indirect ophthalmoscope provided an inadequate view. In this series of 18 procedures, we preformed posterior vitrectomies, removed retained foreign bodies, and reattached persistent retinal detachments. The only major complication was a retinal detachment. Learning to use a monocular system requires practice and preparation with experimental animals.

Adolescent↗
PubMed1980

Weight reduction utilizing a protein-sparing modified fast.

Forty-five grossly obese patients (averaging 64.1 kg. above ideal body weight) were treated as in-patients with a modified protein-sparing fast. Twenty-seven of these patients had diabetes, sixteen of them requiring insulin. In-patient treatment with PSMF ranged from three days to two years. The dietary regimen provided 1.2 gm. protein per kilogram ideal body weight, with no added fat or carbohydrates; this generally amounted to 270 to 430 gm. meat, distributed in three meals (about 500 to 800 kcal per day). Generous vitamin and mineral supplements were provided. Concomitant psychotherapy was also part of the treatment. Before discharge, the patients had lost from 0.45 to 93.2 kg., depending on compliance, length of hospitalization, and amount of exercise. After discharge, compliance fell, despite provision of group therapy with a psychologist and bi-weekly appointments with the physician and dietitian. The more committed patients who attended group therapy regularly have been more successful in continuing to lose weight.

Adult↗
PubMed1980

Osmotically induced retinal detachment in the rabbit and primate. Electron miscoscopy of the pigment epithelium.

Previous work has shown that the injection of a hyperosmotic solution into the rabbit vitreous will cause rapid detachment of the retina. The present experiments show that osmotic detachment also occurs in the monkey eye. No anatomic changes were found to account for the early separation of the retina, but within a few minutes of detachment in the rabbit or several hours in the monkey, the retinal pigment epithelium microvilli lose their normal organization. This may be a nonspecific response to separation from the outer segments. After longer periods of osmotic detachment in the rabbit, the RPE cells became edematous and the microvilli shrank and disappeared. Although some cells ruptured at the apical membrane and large cysts were often observed above the cell junctions, the intercellular tight junctions always appeared intact. Osmolarity should be accounted for in the evaluation of intravitreal injections for man, and care should be used to avoid injection of concentrated solutes near the retina.

Animals↗
PubMed1978

Clinical aspects of ball-bearing bomb injuries.

This paper reports the effects on 22 victims of a bomb containing ball-bearings. Of five patients requiring admission to hospital three had sustained injuries due specifically to ball-bearings. The mechanism of the weapon, and the nature of the injuries are described. The particular type of wounds sustained, their presentation and management are discussed.

Abdominal Injuries↗
PubMed1978

Delayed onset chloroquine retinopathy: case report.

A patient presented with decreased visual acuity and retinal findings compatible with chloroquine retinopathy 5 years after discontinuing regular usage of chloroquine for rheumatoid arthritis. A review of the literature on chloroquine retinopathy is outlined. In addition, the characteristic findings including fluorescein angiography, retinal physiologic studies, and symptoms are reviewed. Chloroquine retinopathy is dose related and essentially irreversible and often progressive once typical findings are noted. To our knowledge very delayed onset of chloroquine retinopathy is a relatively rare phenomenon but the medical and ophthalmic communities must be alerted to the possibly severe complications of this iatrogenic disease entity.

Chloroquine↗
PubMed1975

Formation of steroids by the pregnant mare. V. Metabolism of 14C-isopentenylpyrophosphate and 3H-dehydroisoandrosterone injected into the fetus.

A mixture of 1-14C-isopentenylpyrophosphate and 3H-dehydroisoandrosterone was injected into a horse fetus intramuscularly during laparotomy, after which maternal urine was collected for 4 days. Steroid conjugates in the urine were extracted with Amberlite XAD-2 resin, hydrolysed and separated into phenolic and neutral fractions. From the phenolic fraction estrone, 17alpha-estradiol, equilin and equilenin were isolated. Only estrone and 17alpha-estradiol contained both 3H and 14C, while the ring B unsaturated estrogens contained only 14C. From the neutral fraction 14C-labeled 3beta-hydroxy-5alpha-pregnan-20-one, 5alpha-pregnane-3beta,20beta-diol and 5alpha-pregnan-3beta, 20alpha-diol were isolated. These results demonstrate that the route of biosynthesis of both the ring B saturated and unsaturated estrogens is the same up to the stage of isopentenylpyrophosphate. Thus, the bifurcation in the classical pathway of steroid biosynthesis reported previously by us is occurring at a point after the formation of isopentenylpyrophosphate and prior to the formation of squalene.

17-Ketosteroids↗
PubMedDate not supplied

100 years of the visual cycle.

One--hundred years have passed since Franz Boll and Willy Kühne first characterized rhodopsin and discovered the visual pigment cycle. Some of the events and individuals of that period are described, and color photographs are presented to show the appearance of rhodopsin in the living retina.

Animals↗
PubMedDate not supplied

Microtubule-associated protein 2 (MAP-2): a sensitive marker of seizure-related brain damage.

We have assessed the efficacy of MAP-2 immunohistochemistry as a marker of seizure-related brain damage and its suitability for quantitation of the damage using densitometric and morphometric image analysis. Seizures were produced in rats by administration of 1.5 LD50 soman, an irreversible AChE inhibitor. Our results demonstrate that neuronal damage, assessed using hematoxylin and eosin, and cresyl violet staining, was colocalized on adjacent serial sections with clearly demarcated reductions in MAP-2 staining. The most severely damaged brain regions were devoid of MAP-2 staining. Reductions in MAP-2 immunostaining were found to be exceptionally well suited for quantitation using densitometric and morphometric image analysis. This study represents the first demonstration of seizure-induced excitotoxic alterations in MAP-2.

Animals↗