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Biomedical subjects

G Rose

Publications and source records attributed to G Rose.

At least 163 records · Page 9Linked to original sources
PubMed1986

A temporal-processing mechanism for all species?

Certain species of anurans and electric fish detect amplitude modulations as a means of identifying conspecifics and foreign objects, respectively. This paper provides an account of the similarities between the electrosensory and auditory systems in terms of the mechanisms by which this temporal information is analyzed. Both animals employ a temporal filtering mechanism in this analysis. The transformation from a periodicity coding of amplitude modulations by the peripheral nervous system to a temporal-filter analysis in the central nervous system appears to be present in a number of different animals, ranging from crickets to cats. The possibility of a similar temporal filtering mechanism in humans and its role in perception are discussed.

Animal Communication↗
PubMed1986

G1m(1) and G1m(2) allotypes in Albanian towns of Calabria.

The G1m(1) and G1m(2) allotype distribution was analyzed in a population sample from 11 Albanian towns of Calabria. The unusually high frequency of the G1m(1) marker already observed in Calabria as well as the presence of the Gm(2) phenotype were shown. The Calabrian and Albanian populations were similar, but significantly different from other Italian populations.

Adolescent↗
PubMed1986

Human polymorphic APO-LDL investigated by high-resolution two-dimensional electrophoresis.

The APO part of a human polymorphic low density lipoprotein (LDL) was investigated by two-dimensional electrophoresis. Since these allotypic LDL were purified from sera by specific immunochromatography, the data presented here refer to only one molecular species of LDL. The two-dimensional electrophoresis revealed the presence of isoforms which were correlated to the serological phenotype. A hypothesis about APO-LDL gene organization is outlined.

Apolipoproteins↗
PubMed1985

Neural correlates of temperature coupling in the vocal communication system of the gray treefrog (Hyla versicolor).

The central nervous system of the gray treefrog includes a class of auditory neurons which respond selectively to particular rates of amplitude modulation. When body temperature is increased, the temporal tuning of these neurons shifts to higher rates of modulation. This shift in tuning parallels the temperature-dependent shift in the trill rate in the male's mating call, thus constituting the neural correlate of temperature coupling between the female's behavioral selectivity and the temporal signal characteristics in the male's call.

Animals↗
PubMed1985

Monoamine release from dopamine-depleted rat caudate nucleus reinnervated by substantia nigra transplants: an in vivo electrochemical study.

Previous studies have shown that fetal substantia nigra (SN) transplanted into a cavity overlying a dopamine (DA)-denervated caudate nucleus can reverse a number of the behavioral abnormalities induced by the denervation. While some histochemical and physiological evidence suggests that this reversal is the result of a functional DA input from the transplant to the host brain, there is little direct evidence for transmitter release from ingrowing graft-derived nerve fibers. In the present work in vivo electrochemistry was used to analyse the magnitude, time course and spatial distribution of neurotransmitter releases evoked by local application of potassium (K+) from DA-depleted, SN transplant-reinnervated striatum. Animals were injected unilaterally with 6-hydroxydopamine (6-OHDA) into the SN and screened by measuring apomorphine-induced rotation. Some were then given SN grafts, which were placed in a 'delayed cavity' just dorsal to the lesioned striatum. Nafion-coated graphite epoxy capillary (GEC) electrodes were employed for the electrochemistry to minimize signals derived from ascorbate or acidic DA metabolites. The GEC electrode was fixed to a K+-filled micropipette and this assembly was used to map the caudate nucleus of control, 6-OHDA-treated, and 6-OHDA-treated, grafted animals. The morphometric relationships between striatal recording sites and transplant location were subsequently verified histologically. Releases from striatal sites within 1.0 mm of the SN grafts were slightly, but not significantly, less than those obtained from control caudate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Mortality of employees of the United Kingdom Atomic Energy Authority, 1946-1979.

An analysis was conducted of 3373 deaths among 39 546 people employed by the United Kingdom Atomic Energy Authority between 1946 and 1979, the population having been followed up for an average of 16 years. Overall the death rates were below those prevailing in England and Wales but consistent with those expected in a normal workforce. At ages 15-74 years the standardised mortality ratios (SMRs) were 74 for deaths from all causes and 79 for deaths from all cancers. Mortality from only four causes was above the national average--namely, testicular cancer (SMR 153; 10 deaths), leukaemia (SMR 123; 35 deaths), thyroid cancer (SMR 122; three deaths), non-Hodgkin's lymphoma (SMR 107; 20 deaths)--but in none was the increase significant at the 5% level. Half of the authority's employees were recorded as having been monitored for exposure to radiation, their collective recorded exposure being 660 Sv (65 954 rem). Among these prostatic cancer was the only condition with a clearly increased mortality in relation to exposure. Of the 19 men who had a radiation record and died from prostatic cancer at ages 15-74 years, nine had been monitored for several different sources of exposure to radiation. The standardised mortality ratios were 889 (six deaths) in employees monitored for contamination by tritium, 254 (nine deaths) in those monitored for contamination by other radionuclides, and 385 (nine deaths) in those with dosimeter readings totalling more than 50 mSv (5 rem); but the same nine subjects tended to account for each of these significantly raised ratios. Because multiple exposures were common and other relevant information was not available the reason for the increased mortality from prostatic cancer in this population could not be determined and requires further investigation. Excess mortality rates of 2.2 and 12.5 deaths per million person years per 10 mSv (1 rem) were estimated for leukaemia and all cancers, respectively. The confidence limits around these estimates were wide, included zero, and made it unlikely that the International Commission on Radiological Protection's cancer risk coefficients were underestimated by more than 15-fold. Thus despite this being the largest British workforce whose mortality has been reported in relation to low level ionising radiation exposure, even larger populations will need to be followed up over longer periods before narrower ranges of risk estimates can be derived.

Adolescent↗
PubMed1985

Systolic and diastolic blood pressures as predictors of coronary heart disease mortality in the Whitehall study.

Systolic and diastolic blood pressures were compared as predictors of death due to coronary heart disease using data on the 10 year mortality outcome from the 18 403 male civil servants, aged 40-64, in the Whitehall study. There were 727 deaths due to coronary heart disease. At entry to the study the systolic pressure in these men was significantly higher than the diastolic pressure, and a standardised index of relative risk for death from coronary heart disease was greater for systolic blood pressure. After adjustment for age the top quintile of systolic pressure (greater than 151 mm Hg) identified 5% more men at risk of death from coronary heart disease than for the top diastolic quintile (greater than 95 mm Hg). The findings suggested that clinicians should pay more attention to systolic levels as a criterion for making diagnostic and therapeutic decisions.

Adult↗
PubMed1985

Role of controlled trials in evaluating preventive medicine procedures.

A number of large controlled trials evaluating methods of preventing cardiovascular disease are reviewed, mainly for their methodological lessons. They include trials of treatment for hypertension (Veterans Administration, Australian, and the Hypertension Detection and Follow-up Program); of coronary heart disease prevention by drugs (post-infarction beta-blockers, the WHO trial of clofibrate, and the Lipid Research Clinics Program); and of health education (the Multiple Risk Factor Intervention Trial and the WHO European Multifactorial Trial). Although important evidence has emerged, expectations from large trials of this kind are now more sober. Their findings have to be considered alongside the rest of the evidence, and preventive policy can only be based on a best judgment. Any hope of 'proof' is naive.

Australia↗
PubMed1985

Image analysis of GFA-positive astrocytes from adolescence to senescence.

Smears of fresh rat brain tissue combined with immunohistochemistry using antiserum to glial fibrillary acidic protein (GFA) were used to visualize individual astrocytes in different cortical regions of rats ranging in age from 1 to 30 months. By computerized image analysis, the cell area and the cell perimeter were determined. Using 4-month-old male Sprague-Dawley rats, it was found that GFA-positive astrocytes from cerebellum and hippocampus were significantly larger, both in terms of cell area and cell perimeter, than similar cells from cortex cerebri. The temporal development was carefully followed in smears of the hippocampal formation where a continuous increase in cell size was observed from 1 to 30 months of age. During the first few postnatal months a rapid increase in both cell area and cell perimeter was observed using Sprague-Dawley rats. For studies of senescent animals, Fisher 344 rats specifically bred for aging studies were obtained. Using such animals, a second, highly significant slower growth phase which continued until the longest time points studied was observed. A separate experiment using Sprague-Dawley rats also showed large differences in both cell area and cell perimeter of GFA-positive cerebellum and cortical astrocytes taken from 6-week- and 18-month-old animals. In conclusion, the present study shows that maturation of GFA-positive astrocytes is a process which continues for several months postnatally. This relatively rapid growth phase is followed by a slower increase in cell size, probably continuing throughout life.

Age Factors↗
PubMed1985

Blood pressure patterns in relation to age, weight and urinary electrolytes in three Kenyan communities.

The blood pressure patterns of three Kenyan communities have been studied: 861 members of the Luo tribe in a rural community, 281 members of the Kamba tribe in a rural community and 310 "urban" Luo living in Nairobi. The slope of linear regression of blood pressure with age was significantly different in each population: rural Luo had the smallest rise with age and urban Luo had the largest rise with age, while the Kamba tribe were in between. The differences could not be accounted for by weight. Urinary electrolyte data showed rural Luo had the lowest sodium ratios (sodium/creatinine, sodium/potassium) and the highest potassium/creatinine ratio: urban Luo had the highest sodium and lowest potassium ratios and rural Kamba had values in between. The differences in blood pressures between the two groups of the same tribe in different environments (rural and urban Luo) were far greater than those between different genetic groups (Kamba and Luo) underlining the importance of environmental factor(s) in the determination of arterial pressure. Furthermore, these data support the theory that the dietary intake of sodium and potassium are the major influential environmental factors affecting blood pressure.

Adolescent↗
PubMed1985

WHO European Collaborative Trial of multifactorial prevention of coronary heart disease.

Results are reported from a trial of multifactorial prevention of coronary heart disease (CHD) in occupational groups, involving randomization of 66 factories to intervention and control (49,781 men ages 40 to 59) in the United Kingdom, Belgium, Italy, and Poland. Net average reductions in the intervention factors were 1.2% (plasma cholesterol), 8.9% (daily cigarettes), 0.4% (weight), 2% (systolic blood pressure), and 11% for a combined risk estimate. Reductions were larger in high-risk men (19% for the combined estimate). Red blood cell fatty acid profiles were substantially changed. There was a net overall reduction of 7.4% in fatal CHD and 2.7% in total deaths. Benefits were larger in centers achieving larger risk factor reductions, and in one country--Belgium--the net decreases in CHD incidence and total deaths were significant at the 5% level. Benefit was at least as great in men with established ECG abnormality. It is concluded that CHD risk in middle-aged men seems to be reducible by simple and cost-effective means.

Actuarial Analysis↗
PubMed1985

Use of cyclosporine in pediatric renal transplant recipients.

Cyclosporine and prednisone were used in combination to produce immunosuppression in 18 pediatric recipients of renal allografts. Ten children received cadaveric kidneys and eight received kidneys from living related donors. With a mean follow-up of 16.5 months (range 7 to 33 months), the patient survival rate is 100% (18 of 18) and the graft survival rate is 83% (15 of 18). Two grafts were lost for nonimmunologic reasons. Currently the group mean (+/- SE) serum creatinine concentration is 1.22 +/- 0.11 mg/dl and creatinine clearance is 69.3 +/- 4.79 ml/min/1.73 m2. Cyclosporine nephrotoxicity has not caused irreversible allograft injury nor led to graft loss in this population. The incidence of treated rejection episodes has been 39% (seven of 18). Only 39% (seven of 18) of children have required hospital readmissions since the initial transplant discharge. There have been no opportunistic infections. In the 15 children with functioning grafts, some linear growth has occurred in 10 of 11 prepubertal and two of four postpubertal patients. Cyclosporine and prednisone have constituted a safe, efficacious immunosuppressive regimen for pediatric renal allograft recipients. Longer follow-up will be necessary to confirm whether these advantages persist beyond 2 years.

Adolescent↗
PubMed1985

Sick individuals and sick populations.

Aetiology confronts two distinct issues: the determinants of individual cases, and the determinants of incidence rate. If exposure to a necessary agent is homogeneous within a population, then case/control and cohort methods will fail to detect it: they will only identify markers of susceptibility. The corresponding strategies in control are the 'high-risk' approach, which seeks to protect susceptible individuals, and the population approach, which seeks to control the causes of incidence. The two approaches are not usually in competition, but the prior concern should always be to discover and control the causes of incidence.

Cardiovascular Diseases↗
PubMed1985

Sequential changes in red cell glycolytic enzymes and intermediates and possible control mechanisms in the first two months of postnatal life in lambs.

The sequential changes in several glycolytic enzymes, glucose-6-phosphate dehydrogenase, glycolytic intermediates, and adenosine triphosphate, as well as intracellular pH and plasma inorganic phosphorus were followed simultaneously in eight lambs from birth to 2 months of age. The activities of all glycolytic enzymes and glucose-6-phosphate dehydrogenase were elevated at birth. The 2,3-diphosphoglycerate concentration increased markedly postnatally and was associated with a simultaneous increase in the concentrations of red cell glucose-6-phosphate and total triose phosphate and a decrease in intracellular pH. Inorganic phosphorus also increased and correlated with the 2,3-diphosphoglycerate concentration in the first 10 days of postnatal life. The content of red cell 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate, and ATP increased slightly. These results suggested increased glycolytic flux through the diphosphoglycerate mutase reaction which resulted in net synthesis of 2,3-diphosphoglycerate. The red cell total triose phosphate peaked and fell initially, followed by glucose-6-phosphate and 2,3-diphosphoglycerate suggesting inhibition of phosphofructokinase activity and a decrease in glycolysis secondary to decreased red cell intracellular pH. After 10 days of postnatal life all glycolytic intermediates fell simultaneously, which correlated with a decrease in activity of the glycolytic enzymes.

Aging↗
PubMed1985

Dopaminergic neurotoxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the mouse: an in vivo electrochemical study.

The long-term (i.e., 4-5 months) effects of large doses (3 X 50 mg/kg) of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on striatal dopamine-containing afferents were studied in the NMRI strain of mice. Recently improved in vivo electrochemical methods were first used to examine the magnitude, spatial distribution and temporal dynamics of monoamine release initiated via local application of potassium in various regions of the mouse striatum. Immunohistochemical localization of tyrosine hydroxylase and computer-based image analysis were also used to quantitate regional catecholamine-containing nerve fiber densities in the caudate nucleus. The in vivo electrochemical studies showed a statistically significant decrease in the average potassium-evoked release of electroactive species from the MPTP-treated mouse caudate nucleus vs. control. Greater decreases in release were seen in dorsal than in ventral striatum (55% vs. 33%). The average rise time of potassium-evoked release was also significantly prolonged (greater than 50%) after MPTP pretreatment. Histochemical studies showed an overall reduction in the density of dopamine-containing terminals in the drug-treated mice, with a greater loss observed in the more dorsal regions of the caudate nucleus. The experimental data thus support a long-term selective destruction of dorsal vs. ventral dopamine-containing afferents to the striatum by the neurotoxin MPTP in mice.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1985

Phase and amplitude computations in the midbrain of an electric fish: intracellular studies of neurons participating in the jamming avoidance response of Eigenmannia.

Electric fish monitor modulations in sensory feedback from their own electric organ discharges (EODs) to locate moving objects and to detect interfering EODs of their neighbors. The gymnotoid genus Eigenmannia minimizes detrimental effects of jamming by EODs of its neighbors by shifting its own EOD frequency away from a neighbor's EOD frequency that is too close to its own. Since the animal lowers its own frequency if its neighbor's frequency is higher and raises its frequency if its neighbor's frequency is lower, this jamming avoidance response (JAR) requires that the animal determine the sign of the difference frequency, Df, between the interfering EODs. Eigenmannia obtains this information by evaluating modulations in the amplitude and phase which its nearly sinusoidal EOD signal experiences due to the interference with the neighbor's EODs. The necessary logical operations are executed in the dorsal torus semicircularis, an analogue of the inferior colliculus of higher vertebrates, and are similar to operations underlying directional hearing. By intracellular labeling of physiologically identified cells we have identified the anatomy and functional characteristics of neurons involved in the processing of amplitude and phase information. The JAR is controlled by hierarchical and parallel processing of information in several laminae of somatotopically ordered neurons. Phase differences between signals received by electroreceptors in different parts of the body surface are computed in lamina 6. Information about differential phase is then relayed to multipolar cells in the deeper laminae 8, b and c, which also receive information about modulations in local signal amplitude. These cells are excited by a rise or fall of amplitude as well as by a lead or lag of phase. According to their responses to either of these two variables, these neurons can be divided into four classes. These classes encode all information necessary for the control of the JAR and project to the optic tectum. Dynamic properties and sensory specificities of the JAR are not found in individual, properly tuned neurons but rather emerge statistically from the joint effects of a large population of imprecisely tuned neurons. This system is characterized by a distributed pattern of organization and by the absence of a small number of key neurons whose malfunction would jeopardize the behavioral response. The complexity of this neural machinery appears unnecessary for the logically simple task of the JAR, and it suggests that this behavior was acquired later in evolution by being derived from more general motor responses to moving objects.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗