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Biomedical subjects

K Jackson

Publications and source records attributed to K Jackson.

At least 55 records · Page 3Linked to original sources
PubMed1999

Type IV collagen and laminin regulate glomerular mesangial cell susceptibility to apoptosis via beta(1) integrin-mediated survival signals.

Postinflammatory scarring is characterized by changes in extracellular matrix (ECM) composition and progressive loss of normal resident cells. In glomerular inflammation there is now evidence that unscheduled apoptosis (programmed cell death) of mesangial and other resident cells may mediate progression to irreversible glomerulosclerosis. In the current study we examined the hypothesis that ECM components may differ in their capacity to support mesangial cell survival by suppression of apoptosis. Using a well-established in vitro model of mesangial cell apoptosis, we found that collagen IV and laminin, components of normal mesangial ECM, protected rat mesangial cells from apoptosis induced by serum starvation and DNA damage, by a beta(1) integrin-mediated, but arg-gly-asp (RGD)-independent mechanism. In contrast, collagen I, fibronectin, and osteonectin/SPARC, which are overexpressed in diseased glomeruli, failed to promote rat mesangial cell survival. However, the survival-promoting effect of collagen IV and laminin was not associated with changes in cellular levels of apoptosis regulatory proteins of the Bcl-2 family. These experiments demonstrate that glomerular mesangial cell survival is dependent on interactions with ECM and provide insights into potential mechanisms by which resident cell loss may occur during acute inflammation and postinflammatory scarring of the kidney and other organs.

Animals↗
PubMed1999

The RCN1-encoded A subunit of protein phosphatase 2A increases phosphatase activity in vivo.

Protein phosphatase 2A (PP2A), a heterotrimeric serine/threonine-specific protein phosphatase, comprises a catalytic C subunit and two distinct regulatory subunits, A and B. The RCN1 gene encodes one of three A regulatory subunits in Arabidopsis thaliana. A T-DNA insertion mutation at this locus impairs root curling, seedling organ elongation and apical hypocotyl hook formation. We have used in vivo and in vitro assays to gauge the impact of the rcn1 mutation on PP2A activity in seedlings. PP2A activity is decreased in extracts from rcn1 mutant seedlings, and this decrease is not due to a reduction in catalytic subunit expression. Roots of mutant seedlings exhibit increased sensitivity to the phosphatase inhibitors okadaic acid and cantharidin in organ elongation assays. Shoots of dark-grown, but not light-grown seedlings also show increased inhibitor sensitivity. Furthermore, cantharidin treatment of wild-type seedlings mimics the rcn1 defect in root curling, root waving and hypocotyl hook formation assays. In roots of wild-type seedlings, RCN1 mRNA is expressed at high levels in root tips, and accumulates to lower levels in the pericycle and lateral root primordia. In shoots, RCN1 is expressed in the apical hook and the basal, rapidly elongating cells in etiolated hypocotyls, and in the shoot meristem and leaf primordia of light-grown seedlings. Our results show that the wild-type RCN1-encoded A subunit functions as a positive regulator of the PP2A holoenzyme, increasing activity towards substrates involved in organ elongation and differential cell elongation responses such as root curling.

Arabidopsis↗
PubMed1999

Treatment of Parkinson hypophonia with percutaneous collagen augmentation.

OBJECTIVES: It has been estimated that more than 70% of patients with Parkinson disease experience voice and speech disorders characterized by weak and breathy phonation, and dysarthria. This study reports on the efficacy of treating Parkinson patients who have glottal insufficiency. STUDY DESIGN AND METHODS: Thirty-five patients underwent collagen augmentation of the vocal folds for hypophonia associated with Parkinson disease, using a new technique of percutaneous injection with fiberoptic guidance. Patient response to the collagen augmentation was determined by telephone survey. RESULTS AND CONCLUSIONS: The procedure required minimal patient participation and was safely performed on all the patients who were studied. Results of the survey indicated that 75% of patient responses demonstrated satisfaction with the technique, compared with 16% of patient ratings reflecting dissatisfaction. These results were moderately correlated with the duration of improvement of the dysphonia. Results of this preliminary evaluation demonstrate that voice deficits in Parkinson disease are amenable to vocal fold augmentation. Because this procedure requires minimal patient participation and can be safely performed in an office setting, it may also be useful in other severely debilitating neuromotor diseases that result in glottal insufficiency and hypophonia.

Aged↗
PubMed1999

Single-section counting error when distinguishing between primordial and early primary follicles in sections of rat ovary of different thickness.

UNLABELLED: The number of primordial follicles within an ovary is frequently determined by counting 5, 7 or 10 microns thick sections and multiplying by the fraction of sections counted and a correction factor to adjust for duplicate counts. The objectives of the present study were: (i) to evaluate the accuracy of the correction factor developed by Abercrombie (1946); (ii) to evaluate the accuracy of the classification of primordial follicles from single tissue sections; and (iii) to determine the incorporation rate of 5-bromo-2-deoxyuridine into primordial follicles. In Expt 1, rat ovaries were sectioned at a thickness of 5, 7 or 10 microns. Primordial follicles were counted and classified across ten adjacent ovarian sections. The percentage of primordial follicles from single sections that were counted twice was 10, 9 and 2% in 5, 7 and 10 microns sections, respectively. This was lower than predicted by Abercrombie's method. The major error in counting from single sections was classification of early primary follicles as primordial follicles (55, 33 and 3% in 5, 7 and 10 microns sections, respectively). In Expt 2, a mean of 12 +/- 7% of primordial follicles incorporated 5-bromo-2-deoxyuridine after infusion for 7 days (four of seven rats had no labelled primordial follicles). IN CONCLUSION: (i) Abercrombie's correction factor should not be used for adjusting counts of follicles; (ii) evaluation of primordial follicles from single sections gives inaccurate counts and incorrect classification is of greater importance than duplicate counting, particularly in thinner sections; (iii) for evaluation of the number of follicles, 10 microns is the optimal thickness; and (iv) primordial follicles incorporated 5-bromo-2-deoxyuridine infrequently.

Analysis of Variance↗
PubMed1999

Blue gourami (Trichogaster trichopterus) gonadotropic beta subunits (I and II) cDNA sequences and expression during oogenesis.

We have cloned two cDNAs from the pituitary gland of blue gourami (Trichogaster trichopterus), coding for the beta subunits of the gonadotropin hormones GtH-I and GtH-II. The two cDNAs were sequenced and subjected to sequence analysis. We have found that the deduced amino acid sequences of both cDNAs were most similar to their striped bass counterparts. The beta GtH-I subunits of blue gourami and striped bass shared 73% of their residues, and the beta GtH-II subunits 84%. The cloning of the cDNAs of beta GtH-I and beta GtH-II has enabled us to measure the expression of their respective mRNAs in the pituitaries of female blue gourami at different stages of the reproductive cycle. The highest levels of beta GtH-I and beta GtH-II mRNA were found in specimens classified as high vitellogenic and in females that were at the final stages of oocyte maturation.

Amino Acid Sequence↗
PubMed1998

Immunoblotting of multiple antigenic peptides.

Multiple antigenic peptides (MAPs) can be efficiently separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to a nitrocellulose membrane for subsequent use in immunoblot (IgG and IgM). MAPs can be stained by Coomassie and silver on SDS-PAGE as well as by Fast Green on an immunoblot. Affinity immunoblotting for analysis of antibody clonotype distribution has also been carried out using MAPs. High performance liquid chromatography purification of the MAPs is mainly responsible for their migration as sharp bands in SDS-PAGE and immunoblotting.

Amino Acid Sequence↗
PubMed1998

Growth hormone, sexual maturity and steroids in male carp (Cyprinus carpio).

Samples of pituitary, blood plasma and gonad were taken from male carp. The growth hormones (GH) in the pituitary and plasma were measured in fish of various body weights (BW) and degrees of gonad development, and compared with the levels of 17 beta-estradiol (E2), testosterone (T), 17 alpha-hydroprogesterone (17-P), 11-ketotesterone (11-KT) and progesterone (P) in the testes and plasma. The gonadosomatic index increased rapidly with BW from 100 to 600 g, and then decreased at 900 g. The pituitary GH did not change with BW, but plasma GH was higher in fish weighing 300 +/- 50 and 600 +/- 50 g, than in fish weighing 900 +/- 50 g. In fish weighing 150 +/- 50 to 300 +/- 50 g, the level of T rose significantly in the testes (2.27 ng g-1) and plasma (1.3 ng g-1); E2 was very low in both testes (0-30 pg g-1) and plasma (11-28 pg ml-1), increasing as BW rose from 150 to 600 g. The level of P rose mainly at BW of 300 +/- 50 and 600 +/- 50 g: from 0 to 25 ng g-1 in the testes and from 0 to 17 ng ml-1 in the plasma. The level 17-P rose from 2.5 to 20 ng g-1 in the testes at 600 +/- 50 g BW, but no significant change was recorded in the plasma. The level of 11-KT rose significantly in the tests of fish at 300, 600 and 900 g (0.5-6 ng g-1). The application of different steroids (E2, T and 17-P) on a primary culture of pituitary cells led to the release of GH. Release was significantly higher (P < 0.05) after 4 h at steroid concentrations of 10(-6) M.

17-alpha-Hydroxyprogesterone↗
PubMed1998

Utilization of Child Health Services during the first 18 months of life: aspects of health surveillance in Swedish preschool children based on information in health records.

The aim of this study was to evaluate some aspects of care given within the preventive Child Health Services (CHS) during the first 18 months of life. A national random sample performed on child health records of 172 Swedish preschool children born between 1982 and 1987 was analysed regarding services recorded as having been provided and used within and beyond the national programme of health surveillance. Most families had made visits within the core programme of health surveillance to an optimal or at least sufficient extent. First-time parents visited the CHS more frequently than did more experienced parents. Procedures within the programme, such as growth monitoring, hip examination and immunizations, were documented to have been optimally performed on a majority of the children. Conversely, screening for hearing impairment and assessment of developmental milestones were performed less frequently, as were health information and postnatal parental education. To improve the quality of care, national recommendations ought to be more specific regarding both the performance and the documentation of the service.

Child Health Services↗
PubMed1998

Multiple cranial nerve palsies complicating retrobulbar eye block.

This report details a case of accidental brainstem anaesthesia complicating retrobulbar block for cataract surgery in an 83-year-old man. Prompt diagnosis and treatment resulted in a successful outcome. The many possible presentations of brainstem anaesthesia are described and causative mechanisms are discussed.

Aged↗
PubMed1997

Understanding and enhancing compliance with the second dose of hepatitis B vaccine: a cohort analysis and a randomized controlled trial.

OBJECTIVE: To determine the predictors and extent of noncompliance with a second dose of hepatitis B vaccine and the effectiveness of a compliance enhancement strategy. DESIGN: Cohort analysis and randomized clinical trial. SUBJECTS: A total of 256 consecutive adults attending a sexually transmitted diseases clinic from October 1992 to July 1993 who were seronegative for hepatitis B virus and agreed to receive hepatitis B vaccination. SETTING: Hamilton, Ont. INTERVENTION: Subjects were followed up for 4 months. Those who did not return for the second dose of vaccine by 6 weeks after the first (2 weeks overdue) were randomly assigned to the enhanced intervention group (telephone and mail reminders) or the regular intervention group (mail reminder only). Subjects were considered noncompliant if they did not return for the second dose by 4 months after the first. RESULTS: The risk of not returning for the second dose of vaccine within 4 months after the first was strongly and linearly associated with level of education (p = 0.004). The noncompliance rate among those with less than a grade 10 education was 50%, grade 10-13 education 34%, some college education 15% and some university education 9%. In the randomized controlled trial the enhanced intervention group had twice the compliance rate of the regular intervention group (48% v. 25%; p = 0.008). Subjects with no postsecondary education were highly responsive to the enhanced intervention (relative risk 2.1; p = 0.02) compared with those with a higher level of education (relative risk 1.0; p = 1.0). CONCLUSION: Hepatitis B vaccine recipients with lower educational levels are at increased risk of noncompliance with the second dose of vaccine but are highly responsive to telephone reminders.

Adult↗
PubMed1997

Cochlear implants in children: what constitutes a complication?

The surgeon must ultimately accept the responsibility for any complications that occur as the result of a cochlear implant. Listening to the cochlear implant team members and responding to their needs may enhance the child's progress. Surgical complications, (i.e., skinflap problems, infection, and facial paralysis) are indeed infrequent, but nonsurgical problems are not. Surgical and nonsurgical experiences were reviewed in 55 children. Ages ranged from 23 months to 18 years at the time of cochlear implantation, which occurred from 1984 to 1995. There were no surgical complications. However, the most common surgical obstacle was ossification, which was present in 40% and undetected by computed tomographic scanning in 16.3% of children. Ossification occurred at the round window and scala tympani in 32.7% and involved the cochlea more extensively in 7.3% of children. In only one child was the cochlea entirely ossified. There were, however, many nonsurgical problems that were viewed as complications in patient management. The single most important complication was device failure. This occurred in 10.9% (5/46) of children with the Cochlear Corporation multichannel implant. Head banging and other temper tantrums, parental interference with rehabilitation, socioeconomic factors, poor compliance by the family unit, equipment problems, educational deficiencies, and impatience with habilitative training were some of the other problems.

Adolescent↗