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Biomedical subjects

J Ross

Publications and source records attributed to J Ross.

At least 145 records · Page 8Linked to original sources
PubMed1998

Abnormal myocyte Ca2+ homeostasis in rabbits with pacing-induced heart failure.

To determine whether there are abnormalities in myocyte excitation-contraction coupling and intracellular Ca2+ concentration ([Ca2+]i) homeostasis in pacing-induced heart failure (PF), we measured L-type Ca2+ current (ICa,L) and Na+/Ca2+ exchanger current (INa/Ca) with voltage clamp and measured intracellular Na+ concentration ([Na+]i) and [Ca2+]i with the use of sodium-binding benzofuran isophthalate (SBFI) and fluo 3 in ventricular myocytes isolated from control and paced rabbits. The peak systolic and diastolic levels and the amplitude of electrically stimulated [Ca2+]i transients (0.25 Hz, extracellular Ca2+ concentration = 1.08 mM) were significantly less in PF myocytes. Also, there was prolongation of the times to peak and decline of [Ca2+]i transients. ICa,L density was markedly decreased in PF myocytes. INa/Ca at -40 mV elicited by rapid exposure to 0 Na+ solution with a rapid solution switcher was significantly reduced in PF myocytes, suggesting that the function of the Na+/Ca2+ exchanger is impaired in these myocytes. In PF myocytes the decline of the [Ca2+]i transient when the Na+/Ca2+ exchanger was abruptly disabled was markedly prolonged compared with the decline in control myocytes, consistent with depressed sarcoplasmic reticulum (SR) Ca2+-ATPase function. RNase protection assay showed decreased levels of Na+/Ca2+ exchanger and SR Ca2+-ATPase mRNA in PF hearts, consistent with the function studies. We conclude that the functions of L-type Ca2+ channels, Na+/Ca2+ exchanger, and SR Ca2+-ATPase are impaired in myocytes from rabbit hearts with failure induced by rapid pacing. These abnormalities result in reduced [Ca2+]i transients and systolic and diastolic dysfunction and appear to account for the abnormal ventricular function observed.

Animals↗
PubMed1998

Epileptic pseudodementia.

Dementia is a frequent cause of memory loss with aging. The incidence of complex partial seizures sharply rises after age 60. Complex partial seizures that occur with subtle clinical signs or loss of awareness, or occur during sleep may defy identification. We report five elderly patients fearing dementia in whom memory dysfunction was due to unrecognized complex partial seizures.

Aged↗
PubMed1998

Laparoscopic Swenson Pull-through Procedure for Hirschsprung's Disease.

The introduction of a new procedure into the operating room is always a challenge that requires careful planning and teamwork. This article describes the pathophysiology of Hirschsprung's Disease, the perioperative nursing care required and the operative technique of the Laparoscopic Swenson Pull-Through Procedure.

Hirschsprung Disease↗
PubMed1998

Serum kynurenine-to-tryptophan ratio increases with progressive disease in HIV-infected patients.

An alternative pathway of Trp metabolism involves the conversion of Trp to kynurenine by indoleamine-2,3-dioxygenase, which leads to synthesis of the neurotoxin, quinolinic acid. This study explores the relationship of indoleamine-2,3-dioxygenase activity with stages of HIV infection. Sera from 206 HIV-positive and 72 seronegative subjects were analyzed for Trp and kynurenine. The kynurenine-to-Trp (KT) ratio was calculated. The mean KT ratio of seronegative controls was 36.6 +/- 10.9, and the median ratio was 34.9. The upper limit of the seronegative KT ratio, defined as mean + 2 SD, was 58.4. Patients with HIV infection showed a reciprocal relationship between the KT ratio, the CD4 count, and the stage of the disease. The median KT ratios for asymptomatic and AIDS patients were 50.5 and 117.0, respectively. This study shows that the serum Trp concentration is markedly decreased and that the kynurenine concentration is increased with immune stimulation in HIV infection. This may lead to changes in quinolinic acid and explain some of the pathogenesis of AIDS dementia.

AIDS Dementia Complex↗
PubMed1998

Pulmonary and cardiac function in advanced fibrodysplasia ossificans progressiva.

Fibrodysplasia ossificans progressiva is a rare genetic disease characterized by heterotopic ossification in soft tissues. Severe disability results from progressive immobilization of the limbs, jaw, and chest wall. To determine whether cardiac function is altered in this disease, 25 patients ranging in age from 5 to 55 years (disease duration 1-51 years) were studied. History, physical examination, pulmonary functions, electrocardiography, and echocardiography were performed on each patient. Physical examination of the lungs and heart was unrevealing; no right sided ventricular gallops were heard, and no patient was found to have neck vein distention or peripheral edema. The patients had extremely limited chest expansion (1.9 +/- 0.8 inches), suggesting dependence on diaphragmatic breathing. Lung volumes were severely reduced (mean forced vital capacity 44% +/- 14% of predicted), but flow rates were relatively normal. All patients had normal capillary oxygen saturation. Echocardiography was technically difficult, but no abnormalities of left or right ventricular function were seen. Ten (40%) patients had electrocardiographic evidence of right ventricular dysfunction. Compared with patients without such evidence, these patients were older, had significantly longer disease duration, higher hemoglobin, and more impaired pulmonary function. The results of this study suggest that the presence of severely restrictive chest wall disease is associated with a high incidence of right ventricular abnormalities on electrocardiogram. Whether cor pulmonale will eventually occur remains to be determined.

Adolescent↗
PubMed1998

A study of HLA-DPB1 phenotypes reveals DPB1*6301 in a rural population from Cameroon.

Several recently reported HLA-DPB1 alleles have only been identified in a single family or individuals and are of unknown distribution world-wide. Many new DPB1 alleles appear to arise as a result of gene conversion-like events, which may localize variant DPB1 alleles to the population in which they were first identified. Using two SSOP-based typing methods in parallel, we have identified HLA-DPB1*6301 in an individual from rural Cameroon which has previously only been reported in a family of Mexican-American origin. The presence of DPB1*6301 was confirmed by sequence-based typing of exon 2.

Alleles↗
PubMed1998

The circulating role: who is the most appropriate care provider?

This article describes the long and arduous journey to the development of the Nursing Position Statement-Appropriate Care Provider for the Operating Room in Hamilton and Burlington, Ontario. From the first meeting to the final presentation of the Position Statement to management, it took over a year of intense review. The entire process was done in consultation with the College of Nurses of Ontario, Operating Room Management, educators and staff nurses.

Humans↗
PubMed1997

Polydrug dependence and psychiatric comorbidity among heroin injectors.

The prevalence of diagnoses of substance dependence, anxiety disorders and depressive disorders were estimated in a sample of 222 heroin injectors, using the Composite International Diagnostic Interview. Subjects had a median of three lifetime substance diagnoses and two current diagnoses. A total of 60% met the criteria for a lifetime anxiety disorder, and 51% had a current anxiety disorder. A depressive disorder was diagnosed in 41% of subjects, with 30% having a current diagnosis. There were significant positive correlations between the number of lifetime drug dependence diagnoses and the number of lifetime anxiety and affective disorders (r = 0.41), and the number of current drug dependence diagnoses and the number of current comorbid diagnoses (r = 0.32). After controlling for other variables, the only significant independent predictor of the number of lifetime and current dependence diagnoses was the number of comorbid diagnoses.

Adolescent↗
PubMed1997

Apparent position of visual targets during real and simulated saccadic eye movements.

It is now well established that briefly flashed single targets are mislocalized in space, not only during saccades but also before them. We show here by several techniques (including a vernier judgment that did not require absolute location in space) that errors appear up to 100 msec before saccades are made and are maximal just before they start. The size and even the sign of errors depend strongly on position in the visual field, the complete pattern of errors suggesting a compression of visual space around the initial fixation point and the target of the impending saccade. The compression was confirmed by displaying multiple rather than single targets and was found to be powerful enough to reduce or even to remove vernier offset for pairs of bars shown simultaneously and to create offsets for colinear bars separated in time by 75 msec. It also reduced the apparent number of parallel bars. When saccades were simulated by moving the display at saccadic speed, there were sometimes errors of location, but only for tasks requiring absolute judgment of position. The pattern of errors differed greatly from that during saccades and, in particular, showed no signs of compression. We can model our saccade results by assuming a shift in the point in space associated with eye position compression of eccentricity along the axis of saccades.

Adult↗
PubMed1997

Disruption of the varicella-zoster virus dUTPase and the adjacent ORF9A gene results in impaired growth and reduced syncytia formation in vitro.

Varicella-zoster virus (VZV) open reading frame 8 (ORF8) is predicted to encode the viral dUTPase and the adjacent gene, ORF9A, is thought to encode a membrane protein homologous to HSV-1 UL49.5. A fusion protein, in which the amino portion of glutathione-S-transferase was fused to amino acids 5 to 396 of VZV ORF8 protein, had dUTPase activity in vitro. Construction of a mutant VZV with stop codons or a deletion in the ORF8 gene resulted in loss of viral dUTPase activity. Antibody to VZV ORF9A protein demonstrated a 7-kDa protein located in the membranes of virus-infected cells. Insertion of stop codons into VZV ORF9A resulted in VZV that produced smaller plaques than parental virus. Inactivation of both VZV ORF8 and ORF9A resulted in a virus that grew to lower titers and was impaired for syncytia formation when compared to parental virus. In contrast, a similar mutation in HSV-1 has no effect on growth of the virus in vitro. These results identify loci in the VZV genome that are required for a syncytial phenotype in vitro.

Gene Deletion↗
PubMed1997

Complementary strand analysis: a new approach for allelic separation in complex polyallelic genetic systems.

We describe a method, complementary strand analysis (CSA), for separating alleles potentially from any heterozygous genetic locus. Locus specific PCR is performed generating two allelic products. The antisense strands are isolated and hybridised with a sense reference strand to form a chimeric DNA duplex for each allele which is then separated by non-denaturing PAGE. We demonstrate the application of CSA for separation of highly polymorphic HLA-A, -B and -Cw alleles and characterisation of HLA identity in related bone marrow donors and patients. CSA is capable of resolving one nucleotide differences in a DNA fragment nearly as large as a kilobase in length.

Alleles↗
PubMed1997

The emergence of form by replication.

It is shown with a simple mathematical model that if a system exhibits a given form (a spatial structure) and is put in contact with another system of the same type but in a state of spatial disorder, then under certain conditions their mutual interaction as they evolve in time allows replication of form in the disordered system with a controllable degree of faithfulness.

Biological Evolution↗