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Biomedical subjects

M J Hall

Publications and source records attributed to M J Hall.

139 records · Page 8Linked to original sources
PubMed1971

Influence of metal ions on the formation of mycobactin and salicylic acid in Mycobacterium smegmatis grown in static culture.

Mycobacterium smegmatis was grown on trace-metal-free medium in static culture. Throughout the growth phase, the concentration of mycobactin increased continuously, reaching a maximum of about 30 to 40 mug of mycobactin/mg of cell dry weight after 6 days; the concentration of salicylic acid remained approximately constant at 1 to 2 mug of salicylic acid/mug of cell dry weight. Fe(2+) (or Fe(3+)), Zn(2+), Mn(2+), and Mg(2+) were all essential to a maximum formation of mycobactin. Optimum concentrations required were: Fe(2+), about 1.8 mum; Mn(2+) and Zn(2+), about 0.5 mum; and Mg(2+), at least 0.17 mm. Higher levels of Fe(2+) (9 to 90 mum) and Zn(2+) (2 to 7 mum) repressed mycobactin to about half the maximum value. No other cation or anion apparently is required for mycobactin biosynthesis. Salicylic acid concentration increased about fourfold when iron was omitted from the medium, but this is not as great as the increase reported previously for this strain of M. smegmatis. Mycobactin formation in another strain of M. smegmatis, NCIB 8548, showed similar dependencies on Fe(2+), Zn(2+), and Mn(2+). Maximum accumulation of mycobactin with this strain was 85 mug of mycobactin/mg of dry cell weight, under iron-deficient (1.8 mum Fe(2+)) conditions.

Bacteriological Techniques↗
PubMed1970

Production of the monamycins, novel depsipeptide antibiotics.

Methods are described for the production of the monamycins by Streptomyces jamaicensis in shake flasks and jar fermentors. The effects on the fermentation of variations in pH, temperature, medium composition, volume of inoculum, and strain of the organism are discussed. The methods employed for the extraction and for the microbiological assay of the antibiotics are outlined.

Anti-Bacterial Agents↗
PubMedDate not supplied

A case of subcortical grey matter heterotopia presenting as bipolar disorder.

A case of previously diagnosed bipolar disorder was found to be associated with unilateral subcortical grey matter heterotopia, cortical hemiatrophy, midline shift, and ventriculomegaly on magnetic resonance imaging (MRI). The patient responded to pharmacotherapy with lithium carbonate and carbamazepine. This case dramatically illustrates the need for neuroimaging in psychiatric patients with apparently "functional" affective illness.

Adult↗
PubMedDate not supplied

Long-term exposure to methotrexate induces immunophenotypic changes, decreased methotrexate uptake and increased dihydrofolate gene copy number in Jurkat T cells.

Methotrexate (MTX) treatment of rheumatoid arthritis may require increasing doses to maintain clinical efficacy. An overall plateau of clinical response is reached after only six months of treatment. To study the immunologic, biochemical and genetic effects of MTX on T cells, the Jurkat T cell line was made MTX-resistant by serial addition of methotrexate sodium into culture medium. Cells proliferated and divided successfully in MTX concentrations ranging to 15 microM. MTX resistance of Jurkat T cells in vitro was accompanied by significantly (P < 0.05) decreased expression of CD2, CD3, CD4, CD28, and CD69, IL-2 production, and MTX uptake assessed by cell association or disassociation of 3[H]-MTX or fluoresceinated MTX (FMTX), respectively. In addition, there was DHFR gene amplification and increased levels of DHFR in all resistant cell lines. Both permanent and transient phenotypic changes developed in resultant cell lines exposed to increasing concentrations of MTX in vitro. Expression of CD4 and CD25 and sensitivity to MTX returned to near-parental levels after removal of MTX from culture medium, whereas expression of CD26 and MTX uptake were significantly increased. Expression of CD2, CD3, CD69 and IL-2 production as well as the DHFR levels did not return to the parental phenotype after removal from MTX. We conclude that MTX-cultured cells express depressed levels of cell-surface markers vital for T cell function and activation. The return of enhancement of these cell-surface markers critical to T cell activation suggests a possible mechanism for the severe flares experienced by rheumatoid arthritis patients when drug treatment is discontinued.

Antigens, Differentiation, T-Lymphocyte↗
PubMedDate not supplied

Mg deficiency in chronic inflammatory bowel disease and requirements during intravenous nutrition.

Assessment of magnesium (Mg) status by serum and 24-hr urine estimations has been used to study a group of 17 patients with severe Crohn's disease, 10 of whom have required intravenous (IV) nutrition. Mg depletion was present in 15 (88%) and severe enough to cause symptoms in two. Urine levels were low in most patients and would appear to be a more sensitive indication of Mg depletion than serum levels alone. Serum Mg levels were significantly lower in the Crohn's group than in a group of hospital controls; 5-10 mmol of IV Mg were required daily to prevent Mg depletion during IV nutrition and some patients required higher intakes. Three patients with particularly severe malabsorption required oral Mg supplements in the long-term. The rationale for using our method of assessing Mg status, and the importance of recognizing and treating chronic Mg deficiency are presented.

Adolescent↗
PubMedDate not supplied

Trend data on medical encounters: tracking a moving target.

The National Health Care Survey (NHCS), conducted by the National Center for Health Statistics, consists of separate data collection activities that can be used to track the number and content of health care encounters in the United States. Tracking even something as simple as the number of encounters, however, is complicated by the fact that the content of these encounters changes over time. Results from the NHCS indicate that the U.S. population has been receiving more drugs, more cardiac procedures, more ambulatory surgery, more therapies in nursing homes, and more home health care over time. Policymakers and researchers who examine health care trends should be wary about judging whether the number of length of encounters is positive or negative without also examining the content of these encounters.

Ambulatory Care↗
PubMedDate not supplied

Clinical study of yoga techniques in university students with asthma: a controlled study.

Adult asthmatics, ranging from 19 to 52 years from an asthma and allergy clinic in a university setting volunteered to participate in the study. The 17 students were randomly divided into yoga (9 subjects) and nonyoga control (8 subjects) groups. The yoga group was taught a set of breathing and relaxation techniques including breath slowing exercises (pranayama), physical postures (yogasanas), and meditation. Yoga techniques were taught at the university health center, three times a week for 16 weeks. All the subjects in both groups maintained daily symptom and medication diaries, collected A.M. and P.M. peak flow readings, and completed weekly questionnaires. Spirometry was performed on each subject every week. Analysis of the data showed that the subjects in the yoga group reported a significant degree of relaxation, positive attitude, and better yoga exercise tolerance. There was also a tendency toward lesser usage of beta adrenergic inhalers. The pulmonary functions did not vary significantly between yoga and control groups. Yoga techniques seem beneficial as an adjunct to the medical management of asthma.

Adult↗
PubMedDate not supplied

Ambulatory and inpatient surgery: national patterns for the elderly.

In 1996 the elderly made 13.6 million visits to ambulatory and inpatient settings for surgery. This was 401.0 visits per 1,000 population, which was approximately three and a half times the rate of 114.4 for persons under 65. A total of 25.3 million procedures were performed during these visits. More of the elderly's procedures were performed during inpatient visits (14.5 million procedures) than during ambulatory visits (10.7 million procedures). Three-quarters of the procedures performed on the elderly were in four categories: operations on the eye, cardiovascular operations, operations on the digestive system, and miscellaneous diagnostic and therapeutic procedures. The leading procedures for this age group were extraction of lens, insertion of lens, arteriography and angiocardiography, and endoscopies of small and large intestines. Women who comprised the majority of the elderly population had a larger number of procedures than men, but elderly men had a higher rate per 1,000 population. The 65-74 year-old group had the largest number of procedures, followed by 75-84 year-olds and then the 85 years and older group, reflecting the decreasing population size of these age groups. But the 75-84 year and 85 years and over groups had higher rates of procedures than those aged 65 to 74.

Age Distribution↗
PubMedDate not supplied

National Survey of Ambulatory Surgery: 1994.

In 1994, 27.7 million surgical and nonsurgical procedures were performed during 18.4 million visits to ambulatory surgery settings. Eighty-five percent of the ambulatory procedures (23.4 million) were performed in hospital-based settings and 15 percent (4.3 million) were in freestanding settings. More than half of the ambulatory procedures were in three major categories: operations on the digestive system, the eye and the musculoskeletal system. The leading ambulatory procedures were extraction of lens (performed almost 2 million times), endoscopy of large intestine with or without biopsy (1.8 million) and insertion of prosthetic lens (1.6 million). Women had significantly more ambulatory surgery procedures than men. The ambulatory procedure performed most frequently on children under 15 was myringotomy. Also common for children were tonsillectomies and adenoidectomies. For those aged 15-44, frequently performed ambulatory procedures included endoscopies of large and small intestine; dilation and curettage of uterus; bilateral destruction or occlusion of fallopian tubes; and arthroscopy of knee. In the 45-64 year old group, endoscopies of large and small intestine were the most commonly performed ambulatory procedures. Extraction of lens and insertion of prosthetic lens were the leading ambulatory procedures for those 65 years and older, though endoscopies of large and small intestine were also performed frequently for this age group.

Adolescent↗