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Biomedical subjects

R Sachs

Publications and source records attributed to R Sachs.

At least 37 records · Page 2Linked to original sources
PubMed1992

Visual recovery in two patients after intravenous methylprednisolone treatment of central retinal artery occlusion secondary to giant-cell arteritis.

Two patients with central retinal artery occlusions secondary to biopsy-proven giant-cell arteritis lost visual acuity to no light perception but recovered to baseline acuity after treatment with intravenous methylprednisolone at a dose of 15 to 30 mg/kg/day. The potential advantages and theoretical basis of early and aggressive treatment with large-dose intravenous corticosteroids in arteritic central retinal artery occlusion are discussed.

Aged↗
PubMed1992

Suggested posthypnotic amnesia in psychiatric patients and normals.

The present study examined both quantitative and qualitative hypnotizability differences among four psychiatric patient groups (dissociative disorder (n = 17), schizophrenic (n = 13), mood disorder (n = 14), and anxiety disorder (n = 14) patients), and normals (college students (n = 63). Dissociative disorder patients earned significantly higher corrected total scores on the Stanford Hypnotic Susceptibility Scale, Form C (mean = 7.94), than all other groups. Likewise, dissociative disorder patients initially recalled significantly fewer items when the posthypnotic amnesia suggestion was in effect (mean = .41) and reversed significantly more items when the suggestion was canceled (mean = 3.82) than all other groups. In contrast, schizophrenic patients recalled significantly fewer items when the amnesia suggestion was in effect (mean = 1.85) and reversed significantly fewer items when it was canceled (mean = .77) than the remaining groups. This qualitative difference between schizophrenic patients and the other groups on the suggested posthypnotic amnesia item was observed even though there were no significant quantitative differences between groups in overall hypnotic responsivity.

Adult↗
PubMed1991

Reaction kinetics for the development of radiation-induced chromosome aberrations.

The formation of chromosome aberrations from DNA double-strand breaks (dsb) following ionizing irradiation of cells is analysed using a stochastic, continuous-time Markov chain formalism. A restitution/complete exchange model is proposed which incorporates kinetic competition between dsb restitution and chromosome exchange; it applies primarily to those dsb whose broken ends are held in close proximity by proteins. Some additional pathways for damage evolution are also considered. The calculations are compared in detail to the experiments on dicentric yield and variance in human lymphocytes following acute low-LET irradiation summarized by Lloyd and Edwards (1983) and Lloyd et al. (1987). It was found that dicentric formation by pairwise dsb interactions can lead to a dicentric yield/dose curve with a significant linear component even if one-track action is neglected. In other words a dicentric formation rate quadratic in the dsb number does not automatically imply a dicentric yield quadratic in the dose. However, the data indicate that at least in some experiments there could have been a significant one-track contribution to the dicentric yield in addition to the intertrack contributions analysed in the present paper. From the data the order of magnitude of the dsb interaction rate constant is estimated to be at most approximately 3 x 10(-3) exchanges per dsb pair per hour. It was found that for the reaction pathways considered, a initial Poisson distribution of dsb leads to an underdispersed distribution of dicentrics; the amount of underdispersion is strongly model-dependent and the variance data are consistent with the restitution/complete exchange model. Finally, a general mathematical theorem on Markov models is presented. It implies that assays performed after repair and exchange are completed cannot determine absolute repair or exchange rates, only their ratio (which may depend on lesion number).

Chromosome Aberrations↗
PubMed1991

A temporary focus of savanna species of the Simulium damnosum complex in the forest zone of Liberia.

Savanna species of the Simulium damnosum complex, the major vectors of the blinding savanna type of onchocerciasis, were considered to be rare in Liberia, until the dry season of 1988. In 1988 they became a serious nuisance, biting people at the Bong iron ore mine within the rain forest zone. S. damnosum s.str. and S. sirbanum were found breeding, in association with S. adersi a non man-biting savanna species, in a stream emerging from the mine's tailings pond. The local forest species were extremely rare in this stream. The water of the stream was characterized by an increased hardness and higher temperatures in comparison with those of natural watercourses in the area. The mass occurrence of flies was probably related to expansions of the tailings ponds, when rich nutrition was provided for the blackfly larvae by the decaying forests submerged by the rising water levels. The phenomenon did not recur in 1989 when only a few savanna flies were caught, and none were seen in the dry season of 1990. Although it is not known why the artificial environment of the tailings ponds was so attractive for the savanna species the events clearly demonstrated that savanna flies seasonally invading the area, possibly aided by the northeasterly harmattan winds, can become established in the rain forest zone if suitable conditions are met. No infections with Onchocerca volvulus were found in more than 1000 flies caught by vector collectors but, after experimental infection with the local forest strain, a few parasites developed to the infective stage. As yet there is no evidence that the occurrence of savanna flies in the rain forest zone of Liberia was of epidemiological significance.

Animals↗
PubMed1991

The dwarf river crab Liberonautes latidactylus nanoides Cumberlidge & Sachs, 1989, from Liberia--a new second intermediate host of Paragonimus uterobilateralis.

Large populations of the dwarf river crab Liberonautes latidactylus nanoides Cumberlidge & Sachs, 1989, collected from the St. Paul river at the Haindi/Mauwa focus of paragonimiasis in Liberia were examined for parasitization by the human lung fluke, Paragonimus uterobilateralis. Four specimens out of 763 L. l. nanoides proved to be positive for P. uterobilateralis (0.52%), and each of these specimens contained only 1 metacercaria. The dwarf river crab forms the basis of a seasonal commercial fishery in Liberia, and it is sold for human consumption in rural markets. However, the low levels of parasitization of L. l. nanoides, together with its limited seasonal availability make it doubtful that L. l. nanoides constitutes a public health risk to the rural population of Liberia.

Animals↗
PubMed1990

Distribution of metacercariae in freshwater crabs in relation to Paragonimus infection of children in Liberia, West Africa.

An explanation was sought for the high prevalence of paragonimiasis in children in Liberia by examining possible modes of human infection from freshwater crabs. The occurrence, frequency of infection, and distribution of metacercariae of Paragonimus uterobilateralis in the freshwater crab Liberonautes latidactylus were studied. The muscles of the cephalothorax and of the legs were found to be the most frequently and most heavily infected parts of the crab. A likely risk of infection of children was considered to be the habit of chewing on, or ingesting in a raw state, the walking legs of infected crabs. Possible contamination of the hands of cooks with metacercariae from the internal organs or haemolymph of infected crabs was thought to be a minor route of infection.

Animals↗
PubMed1989

Isolation of microcercous cercariae from snails caught in an endemic focus of Paragonimus uterobilateralis in Liberia, West Africa.

Microcercous cercariae have been recovered from the snail Homorus (Striosubulina) striatella RANG. which were collected in a focus of human lung fluke disease in Liberia, West Africa, and are here described. Metacercariae of Paragonimus uterobilateralis were isolated from freshwater crabs (Liberonautes latidactylus) captured at the same location, and at the same time, as the infected snails. The dimensions of the Liberian cercariae have been found to differ markedly from those of a cercaria from Cameroon previously described as that of Paragonimus africanus. The structure and dimensions of the Liberian cercariae clearly resemble those of the cercariae of other species of Paragonimus from Asia and America.

Animals↗
PubMed1988

Use of the quadriceps active test to diagnose posterior cruciate-ligament disruption and measure posterior laxity of the knee.

Orthopaedic surgeons routinely use passive tests, in which the displacing force is applied externally, to evaluate the integrity of the ligaments of the knee. Using a quadriceps active test, in which the muscle contractures of the subject served as the displacing force, tibial displacement was measured with an arthrometer in ninety-two subjects: sixty-seven who had an acute or chronic rupture of the posterior or anterior cruciate ligament and twenty-five who had normal knees. With the knee joint in 90 degrees of flexion, contraction of the quadriceps resulted in anterior translation of the tibia in forty-one of forty-two knees that had a documented disruption of the posterior cruciate ligament. This anterior translation did not occur in the contralateral, normal knee of the same subjects; in the knees of the twenty-five normal subjects; or in twenty-five knees that had a known unilateral anterior cruciate-ligament disruption.

Adolescent↗
PubMed1987

Isoenzymes of the lung fluke Paragonimus uterobilateralis from Liberia.

The enzymes of 35 adult Paragonimus uterobilateralis were analysed using thin-layer starch gel electrophoresis. From a total of 21 enzyme systems studied, 15 proved to be useful for the description and recognition of this species. All individuals were identical concerning 11 enzymes. In four remaining enzymes, alanine aminotransferase (ALAT, hexokinase, aspartate aminotransferase and phosphogluconate dehydrogenase, two or three variants, also being partly typical for this species were observed. In a comparison involving seven different enzymes, there were no differences between the electrophoretic patterns of 35 adult and 24 juvenile P. uterobilateralis. Additional examinations of 30 adult P. uterobilateralis with isoelectric focusing on ultrathin-layer polyacrylamide gels revealed clearer separations of enzymes. The method showed corresponding results or identiy of all individuals tested with three representative enzymes (ALAT, glucosephosphate isomerase and adenylate kinase).

Alanine Transaminase↗
PubMed1986

Isoenzymes of South American Paragonimus peruvianus and P. ecuadoriensis.

The characterization of adult Paragonimus peruvianus by isoenzyme electrophoresis of four enzymes, a peptidase, alanine aminotransferase, glucosephosphate isomerase and glucose 6-phosphate dehydrogenase revealed a complete identity of all six individuals examined. Electrophoretic patterns of eight Paragonimus ecuadoriensis showed uniformity concerning the same enzymes. Both species compared were monomorphous with respect to three enzymes and could only be separated by the peptidase. The close relationship, already established by morphology, between adults of P. peruvianus is therefore supported.

Alanine Transaminase↗