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Biomedical subjects

T Johnston

Publications and source records attributed to T Johnston.

At least 37 records · Page 2Linked to original sources
PubMed1995

The aldehyde dehydrogenase ALDH2*2 allele exhibits dominance over ALDH2*1 in transduced HeLa cells.

Individuals heterozygous or homozygous for the variant aldehyde dehydrogenase (ALDH2) allele (ALDH2*2), which encodes a protein differing only at residue 487 from the normal protein, have decreased ALDH2 activity in liver extracts and experience cutaneous flushing when they drink alcohol. The mechanisms by which this allele exerts its dominant effect is unknown. To study this effect, the human ALDH2*1 cDNA was cloned and the ALDH2*2 allele was generated by site-directed mutagenesis. These cDNAs were transduced using retroviral vectors into HeLa and CV1 cells, which do not express ALDH2. The normal allele directed synthesis of immunoreactive ALDH2 protein (ALDH2E) with the expected isoelectric point. Extracts of these cells contained increased aldehyde dehydrogenase activity with low Km for the aldehyde substrate. The ALDH2*2 allele directed synthesis of mRNA and immunoreactive protein (ALDH2K), but the protein lacked enzymatic activity. When ALDH2*1-expressing cells were transduced with ALDH2*2 vectors, both mRNAs were expressed and immunoreactive proteins with isoelectric points ranging between those of ALDH2E and ALDH2K were present, indicating that the subunits formed heteromers. ALDH2 activity in these cells was reduced below that of the parental ALDH2*1-expressing cells. Thus, the ALDH2*2 allele is sufficient to cause ALDH2 deficiency in vitro.

Aldehyde Dehydrogenase↗
PubMed1994

Nursing caries: literature review and report of a case managed under local anaesthesia.

Although the prevalence of dental caries in children has fallen in recent years, significant numbers of children are still treated for nursing caries. This form of rampant caries affects the primary dentition and causes rapid destruction of normally resistant surfaces. The treatment of nursing caries is multifactorial, involving the child, parents, dental team and other health care providers to ensure the restorative dental treatment is supported by parental education in caries prevention, oral hygiene and infant nutrition. This paper presents a literature review on the condition, followed by a case report of a child with nursing caries treated in the clinic under local anaesthesia.

Anesthesia, Dental↗
PubMed1993

Autopsy findings in a severely affected infant with a 2q terminal deletion.

We describe a 37-week gestation female infant who was born with a terminal 2q deletion. Both of her parents had normal chromosomes. This infant had multiple anomalies, including hypertelorism, short palpebral fissures, microphthalmia, cleft lip/cleft palate, and abnormal ears. Autopsy documented Dandy-Walker malformation with severe hydrocephalus, aortopulmonary window, secundum atrial septal defect, duodenal atresia, incomplete rotation of the bowel, gonadal dysgenesis, uterus didelphys, and musculoskeletal defects. Compared with the other 6 children with 2q terminal deletion documented in the literature, this patient is the most severely affected. This patient is also the only one documented to have died and undergone autopsy examination. The findings in this case provide more data for the eventual description of a "terminal 2q deletion syndrome" and suggest that some abnormalities, such as gonadal dysgenesis, may be present in living children with this chromosome abnormality.

Abnormalities, Multiple↗
PubMed1993

Drosophila forkhead homologues are expressed in a lineage-restricted manner in human hematopoietic cells.

The forkhead gene (FKH) regulates morphogenesis in Drosophila. It is the prototype of a new family of transcriptional activators. Partially degenerate oligonucleotides to two conserved amino acid sequences of this family were used to prime a polymerase chain reaction (PCR) amplification of HEL cell cDNA. Two unique clones, designated H3 and H8, were isolated that contained homologies to FKH. A third novel clone, 5-3, was isolated by low stringency screening of a chronic myelogenous leukemia cDNA library using H8 as a probe. H3 and 5-3 are preferentially expressed in restricted hematopoietic lineages, while the expression of H8 was ubiquitous. Southern analysis showed that FKH 5-3 is conserved through yeast, which is rare among tissue-specific transcription factors. The H3 and 5-3 clones provide evidence that FKH family members are present in a tissue-restricted manner in humans.

Amino Acid Sequence↗
PubMed1993

Chronic thromboxane synthase inhibition with CGS 12970 in human cyclosporine nephrotoxicity.

CsA nephrotoxicity in rats is associated with an increase in renal thromboxane production. Treatment with selective thromboxane synthase inhibitors or receptor antagonists improves renal function in these animal models. In humans, it is unclear whether intervention aimed at reducing the effects of thromboxane on the kidney will be clinically useful. However, we reported previously that thromboxane metabolite excretion is increased in CsA-treated renal allograft recipients with evidence of CsA toxicity and that 48-hr intravenous infusion of the selective thromboxane synthase inhibitor CGS 13080 improves renal function in such patients. We undertook the present study to determine the effect of more prolonged treatment with an oral thromboxane synthase inhibitor, CGS 12970, in renal transplant recipients taking CsA. We measured glomerular filtration rate and p-aminohippurate clearance before and after 4 weeks of treatment with CGS 12970 in 13 patients with renal allografts who had been treated with CsA for a mean 6.3 months and had mild renal insufficiency. Baseline serum creatinine was 1.8 +/- 0.3. Treatment with CGS 12970 resulted in 83% inhibition of urinary thromboxane B2 (TXB2), 93% inhibition of 2,3-dinor-TXB2, and 89% inhibition of 11-dehydro-TXB2, but no change in the urinary excretion of prostacyclin metabolites. However, suppression of urinary thromboxane metabolites to these levels did not significantly affect renal function. Glomerular filtration rate was 45 +/- 4 ml/min/1.73 m2 at baseline and 43 +/- 4 ml/min/1.73 m2 after 4 weeks of treatment with CGS 12970. Estimated renal plasma flow was 272 +/- 21 ml/min/1.73 m2 at baseline and 251 +/- 38 ml/min/1.73 m2 with thromboxane synthase inhibition. Thus, substantial suppression of thromboxane production with CGS 12970 did not improve renal function in CsA-treated renal allograft recipients.

Adult↗
PubMed1992

Population, education and sustainable development.

The author examines the interrelationships between population growth and education, with a focus on Sub-Saharan Africa. "The gross body of evidence suggests that for all developing regions (and for sub-saharan Africa specifically) rapid population growth deleteriously impacts upon the quantity and quality of schooling. In a reciprocal fashion, the variables which underpin rapid and differential growth (fertility, mortality and migration) are themselves influenced by quantum of formal schooling and by other educational processes."

Africa↗
PubMed1991

Papilliferous keratoameloblastoma.

A case of papilliferous keratoameloblastoma is reported which is only the second ever documented. The patient was a 76-yr-old black woman with a large expansile multilocular radiolucency of the body, angle and ramus of the mandible. Histologically the lesion consisted of sheets of cystic follicles filled with necrotic debris and sometimes parakeratin. The vast majority of the follicles were lined by a papilliferous epithelium consisting of large rounded cells with centrally placed nuclei. True papillary projections with cores of connective tissue were also present. The remainder of the follicles were lined by a thin parakeratinising stratified squamous epithelium. Histological features characteristic of ameloblastoma were absent. Final classification of these lesions will have to await the reporting of further cases.

Aged↗
PubMed1990

Ten years of training community urologists and general surgeons to do cadaver kidney retrievals.

We trained 82 community hospital cadaver kidney retrieval teams during a 10-year period ending June 30, 1987. During the last 5 years of that period the concept of multiple organ retrieval was introduced into the training sessions and 429 cadaver kidney grafts were retrieved. Of those kidneys 292 were transplanted at our hospital, and the function of 220 cadaver kidney grafts retrieved by the community hospital teams was compared to that of 72 retrieved by the transplant center retrieval team. Of the cadaver kidney transplants 114 were from multiple organ donors. There was no significant difference in 1-month serum creatinine nadir of surviving grafts (2.1 +/- 1.8 versus 1.9 +/- 1.7 mg. per dl.), 6-month serum creatinine level (1.7 +/- 0.8 versus 1.6 +/- 0.6 mg. per dl.), 12-month serum creatinine level (1.8 +/- 0.9 versus 1.6 +/- 0.6 mg. per dl.) and 5-year actuarial graft survival (44.8 +/- 4.1 versus 52.4 +/- 7.5%), with the community hospital data presented first. The delayed graft function rate was significantly higher in the recipients of cadaver kidney grafts retrieved by community hospital teams (54 versus 35%), which was reduced by the in situ flush technique. There was no significant difference in delayed graft function rate (48 versus 40%) for the 114 cadaver kidney transplants retrieved from multiple organ donors by either community hospital or transplant center teams. With continuing education and quality control, community hospital retrieval teams can provide kidneys satisfactory for transplantation, even when working with multiple organ retrieval teams.

Actuarial Analysis↗
PubMed1990

Retirement: what happens to the marriage.

The focus of this descriptive study was to examine what happens to the marriage at retirement. The data were to serve as a basis for further investigation toward the creation of a marital enhancement program at retirement. Purposeful sampling was used to identify the 10 couples who were involved in the study. Findings from this study indicated that an effective marital enhancement program at retirement would consider the following factors: changes in roles and identity were significant stressors during this time; the communication of thoughts was more frequent than the communication of feelings; spouses became increasingly aware of their partners' faults during retirement; men appeared to be more satisfied in retirement than their wives; hobbies and time spent together did not change following retirement; children served as important topics of conversation and sources of pride and thought; time spent with children following retirement did not increase; and children were often unaware of the challenges and changes faced by their parents at retirement.

Female↗
PubMed1988

Blood pressure and blood lead concentration in bus drivers.

San Francisco bus drivers have an increased prevalence of hypertension. This study examined relationships between blood lead concentration and blood pressure in 342 drivers. The analysis reported in this study was limited to subjects not on treatment for hypertension (n = 288). Systolic and diastolic pressures varied from 102 to 173 mm Hg and from 61 to 105 mm Hg, respectively. The blood lead concentration varied from 2 to 15 micrograms/dL. The relationship between blood pressure and the logarithm of blood lead concentration was examined using multiple regression analysis. Covariates included age, body mass index, sex, race, and caffeine intake. The largest regression coefficient relating systolic blood pressure and blood lead concentration was 1.8 mm Hg/ln (micrograms/dL) [90% C. I., -1.6, 5.3]. The coefficient for diastolic blood pressure was 2.5 mm Hg/ln (micrograms/dL) [90% C. I., 0.1, 4.9]. These findings suggest effects of lead exposure at lower blood lead concentrations than those concentrations that have previously been linked with increases in blood pressure.

Adult↗
PubMed1986

Differential haemodynamic effects induced by beta 1-(bisoprolol) or beta 2-(ICI 118,551) adrenoceptor blockade in man.

To characterize beta 1- and beta 2-adrenoceptor mediated effects in man the influence of the selective beta 1-adrenoceptor antagonist bisoprolol and the selective beta 2-adrenoceptor antagonist ICI 118,551 on changes in blood pressure, heart rate and lymphocyte beta 2-adrenoceptor density evoked by dynamic exercise or isoprenaline infusion was studied in 12 male normotensive volunteers. Bisoprolol administration (1 X 10 mg/day) did not affect lymphocyte beta 2-adrenoceptor density, while ICI 118,551 (3 X 25 mg/day) increased it by about 40%. Exercise as well as isoprenaline infusion caused 100% increases in lymphocyte beta 2-adrenoceptor density; these increases were completely abolished by ICI 118,551, but not affected by bisoprolol. ICI 118,551 markedly attenuated isoprenaline-induced decrease in diastolic blood pressure, but did not affect increase in systolic blood pressure; on the contrary, bisoprolol inhibited the isoprenaline-evoked increase in systolic blood pressure, but did not affect the decrease in diastolic blood pressure. ICI 118,551 antagonized the isoprenaline-induced tachycardia much more potently than bisoprolol, while bisoprolol, but not ICI 118,551, suppressed exercise-induced tachycardia. It is concluded that exercise-induced tachycardia is mediated by cardiac beta 1-adrenoceptor stimulation, whereas isoprenaline-induced tachycardia is mediated by both beta 1- and beta 2-adrenoceptor stimulation.

Adrenergic beta-Antagonists↗
PubMed1985

Effect of low-dose argon irradiation on rate of wound closure.

Four open circular wounds were made on the backs of each of ten guinea pigs by excising approximately 2-cm areas of full-thickness skin and subcutaneous tissue. Every 2 or 3 days, one of the four wounds was treated with 2 J/cm2 argon laser, one washed and treated, one only washed, and one receiving no treatment. The area of the remaining open wound was traced on a glass microslide. A tenth guinea pig received the same "treatments" but the laser was not turned on. The wounds receiving different treatments were randomly selected on different guinea pigs. The area of open wound remaining was measured with a planimeter, and the rate of healing was plotted for each. The numbers of days required for 50 and 75% healing were determined. All wounds were coded and the results determined by an independent observer. We found no difference in the rate of healing of any of these wounds and, under these experimental conditions, found no effect on the overall rate of wound healing by low-dose argon laser exposure.

Animals↗
PubMed1979

Prison health and medical education.

Prison health has long been neglected as an area of serivice by organized medicine and a site for clinical education by health science centers. The University of New Mexico Health Science Center offers an elective, weekly clinical experience for preclinical medical students, senior nursing students, and senior pharmacy students at a prison facility in need of medical services. Students' reaction to the prison experience was strongly positive. Most developed empathy toward the inmates and a greater understanding of prison health problems. Inmates rated the student service highly and requested its continuation. This community health education experience has provided a noncontractual model of a university-prison health alliance.

Ambulatory Care Facilities↗