Search PubMed⌕ Search

Biomedical subjects

G R Boss

Publications and source records attributed to G R Boss.

70 records · Page 4Linked to original sources
PubMed1982

Expression of the marker (X) (q28) in lymphoblastoid cell lines.

The marker(X)(q28) chromosome associated with one type of X-linked mental retardation has been demonstrated in lymphoblastoid cell lines established from affected individuals. The mar(x) can reliably and repeatedly be seen by the addition of FUdR to the cultures for 24 hrs prior to harvest. This simple technique provides an excellent in vitro experimental test system for investigation of the mar(X).

Cell Line↗
PubMed1981

Decreased rates of methionine synthesis by methylene tetrahydrofolate reductase-deficient fibroblasts and lymphoblasts.

Methionine synthesis from homocysteine was measured in intact human fibroblasts and lymphoblasts using a [14C]formate label. Seven fibroblast lines and two lymphoblast lines derived from patients with 5,10-methylene tetrahydrofolate reductase deficiency had rates of methionine synthesis that were from 4 to 43% of normal. When the patients were divided by clinical status into mildly (two patients), moderately (two patients), and severely (three patients) affected, methionine biosynthesis expressed as a percent of control values was 43 and 33%, 11 and 10%, and 7, 6, and 4%, respectively, in fibroblasts. Similar data for the two lymphoblast lines were 36 and 26% for a mildly and moderately affected patient, respectively. These data are to be contrasted with the measurement of residual enzyme activity in cell extracts which agrees less precisely with the clinical status of the patients. In the presence of normal methionine synthetase activity, the rate of synthesis of methionine from homocysteine is a function of the activity of the enzyme 5,10-methylene tetrahydrofolate reductase, and measurement of the methionine biosynthetic capacity of cells deficient in this enzyme accurately reflects the clinical status of the patient from whom the cells were derived.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1981

Age-related physiological changes and their clinical significance.

Physiological changes occur with aging in all organ systems. The cardiac output decreases, blood pressure increases and arteriosclerosis develops. The lungs show impaired gas exchange, a decrease in vital capacity and slower expiratory flow rates. The creatinine clearance decreases with age although the serum creatinine level remains relatively constant due to a proportionate age-related decrease in creatinine production. Functional changes, largely related to altered motility patterns, occur in the gastrointestinal system with senescence, and atrophic gastritis and altered hepatic drug metabolism are common in the elderly. Progressive elevation of blood glucose occurs with age on a multifactorial basis and osteoporosis is frequently seen due to a linear decline in bone mass after the fourth decade. The epidermis of the skin atrophies with age and due to changes in collagen and elastin the skin loses its tone and elasticity. Lean body mass declines with age and this is primarily due to loss and atrophy of muscle cells. Degenerative changes occur in many joints and this, combined with the loss of muscle mass, inhibits elderly patients' locomotion. These changes with age have important practical implications for the clinical management of elderly patients: metabolism is altered, changes in response to commonly used drugs make different drug dosages necessary and there is need for rational preventive programs of diet and exercise in an effort to delay or reverse some of these changes.

Age Factors↗
PubMed1980

Ecto-5'-nucleotidase activity in lymphoblastoid cell lines derived from heterozygotes for congenital X-linked agammaglobulinemia.

Lymphoblastoid cell lines were established from female relatives of patients with congenital X-linked-agammaglobulinemia by Epstein-Barr virus transformation of their peripheral B lymphocytes. Cell lines derived from presumed carriers were characterized by low ecto-5'-nucleotidase activity and a reduced percentage of surface immunoglobulin-bearing cells. Measurement of ecto-5'-nucleotidase activity in newly established lymphoblastoid cell lines may provide a means for the identification of heterozygotes for congenital X-linked agammaglobulinemia.

5'-Nucleotidase↗
PubMed1980

Age-dependency of lymphocyte ecto-5'-nucleotidase activity.

The activity of lymphocyte ecto-5'-nucleotidase (ecto-5'-NT) decreases with advancing age, T lymphocyte ecto-5'-NT activity begins to fall after the age of 40 and subjects in the 41 to 50, 51 to 60, 61 to 75, and 75 to 85 age ranges of life have 57, 52, 38, and 19%, respectively, of the T lymphocyte ecto-5'-NT activity of subjects under the age of 40. TG cells (suppressor cells) have 39% of the ecto-5'-NT activity of Tnon-G cells (helper cells) but the increase in numbers of TG cells that occurs with age explains only about 14% of the age-related fall in T lymphocyte ecto-5'-NT activity. B lymphocyte ecto-5'-NT activity remains stable until age 60 and subjects over 60 years of age have 42% of the B lymphocyte ecto-5'-NT activity of subjects under age 60.

5'-Nucleotidase↗
PubMed1980

Failure of folic acid (pteroylglutamic acid) to affect hyperuricemia.

PGA administered in doses up to 1000 mg orally a day did not significantly lower the serum urate concentration nor decrease the urinary urate or total oxypurine excretion in five hyperuricemic subjects. The folate was well absorbed, as reflected by marked increases in the serum and erythrocyte folate concentrations, and up to 50% of the administered folate could be recovered in the urine. There was no evidence of clinical or laboratory toxicity at these high doses of folate. PGA is a weak inhibitor of human liver xanthine oxidase in vitro, and much of its inhibitory effect is secondary to trace contamination by pterin-6-aldehyde, a potent inhibitor of the enzyme.

Adult↗
PubMed1979

Acquired C1 esterase inhibitor deficiency and angioedema: a review.

A case of acquired C1INH deficiency with angioedema is described. Fifteen cases are thus far recorded. The clinical syndrome of angioedema in these patients closely resembles hereditary angioedema (HAE). Most cases are associated with a paraprotein, cryoglobulin, or autoantibody, which presumably initiates C1 activation and C1 Inhibitor consumption. C1INH, C4 and C2 levels are low in acquired C1INH deficiency, as in HAE. A distinguishing feature is that C1 titers are very low in the acquired disease and only minimally depressed, if at all, in HAE. Most cases have appeared in patients with an underlying lymphoproliferative or autoimmune disease. Therapy is directed at the underlying disorder, but androgen therapy may be helpful in preventing attacks. Future potential therapeutic approaches are discussed.

Angioedema↗
PubMed1979

Ecto-5'-nucleotidase activity in T and B lymphocytes from normal subjects and patients with congenital X-linked agammaglobulinemia.

Ecto-5'-nucleotidase activity was measured in lymphocyte subpopulations isolated from normal subjects and patients with congenital X-linked agammaglobulinemia. B lymphocytes from normal subjects have at least three times more ecto-5'-nucleotidase activity than T lymphocytes. Patients with X-linked agammaglobulinemia have 56% of normal activity in their T cells, and lack a lymphocyte subpopulation high in nucleotidase activity. High activity of ecto-5'-nucleotidase may be a biochemical marker for mature surface immunoglobulin-bearing B cells.

Agammaglobulinemia↗
PubMed1977

Circulating anticoagulant in the procainamide-induced lupus syndrome.

An elderly man with procainamide hydrochloride-induced lupus syndrome had a circulating anticoagulant against factor XI and a biologic false-positive (BFP) test result for syphilis. This was not associated with hemorrhagic problems. The activity of the circulating anticoagulant and the BFP disappeared within days following discontinuation of procainamide and the administration of corticosteroids.

Aged↗
PubMedDate not supplied

A long-term study of the absorption of large oral doses of folic acid.

Large daily doses of oral folic acid ranging from 25 to 1,000 mg and totalling between 1,875 and 16,000 mg per course of treatment were well tolerated without any evidence of toxic effects by four hyperuricemic men of the ages of 26, 38, 46 and 50 years. The minimum folate absorption in the gut as measured by urinary excretion ranged from 10.1 to 45.7 percent. The percentage of absorption within a give patient remained similar in successive courses and there was no evidence of saturation of the absorption process related to dose or time. The pattern of urinary excretion of folates did not indicate that appreciable fractions relative to the large folate doses were retained by the patients. Serum, erythrocyte, and urine folates returned to pretreatment levels within 120 days after treatment. These findings suggest that the folate stores of the body do not expand by orders of magnitude even when megadoses of folates are absorbed in the gut. The rise of the folate levels in erythrocytes was gradual and continuous during treatment and is best explained by postulating that incorporation of folate into red cell takes place mostly at the precursor and reticulocyte stages. The decrease of erythrocyte folate values seen 40 to 66 days after folate treatment indicates that the folate content of erythrocytes diminishes during their life span.

Adult↗