Search PubMed⌕ Search

Biomedical subjects

J Barlow

Publications and source records attributed to J Barlow.

At least 109 records · Page 6Linked to original sources
PubMed1981

Ultrastructural changes accompanying the growth of isolated oligodendrocytes.

The changes in the ultrastructure of oligodendrocytes with time in culture were examined by transmission electron microscopy. Oligodendrocytes were isolated from ovine white matter and maintained in Dulbecco's modified Eagle's medium supplemented with 20% horse serum. One day after being placed in plastic culture dishes, most cells aggregate into clusters that do not attach to the surface for several days. Cells within these clusters form junctional complexes resembling gap junctions, their nuclear chromatin becomes uniformly dispersed, they are rich in polyribosomes, and their cytoplasm is less osmiophilic than oligodendrocytes in ovine white matter or cells fixed immediately after isolation. After several days in culture, the cells become attached to the plastic surface, chromatin once again becomes clumped beneath the nuclear membrane, rough endoplasmic reticulum accumulates within the cytoplasm and the cells extend long processes containing cytoplasmic organelles. From these observations, it appears that oligodendrocytes undergo a transient dedifferentiation during their recovery from the trauma of isolation, not unlike the central chromatolysis seen in neurons following axonal injury. After acclimatization to tissue culture conditions, isolated oligodendrocytes show many of the morphologic features seen in vivo and therefore offer a good model to study myelination.

Animals↗
PubMed1981

Energy malabsorption: measurement and nutritional consequences.

Fecal energy (FE) loss was measured using bomb calorimetry in 30 patients; 14 had a history of malabsorption, while 16 had no history of intestinal dysfunction. Average digestibility (and range) of energy and FE loss were 73% (48 to 91%) and 493 kcal/day (177 to 927 kcal/day) in the group with malabsorption, compared to 96% (89 to 99%) and 74 kcal/day (8 to 146 kcal/day) in the group without malabsorption, respectively. Metabolizable energy supplied by the diet (intake kcal -- (fecal kcal + urinary kcal) was below the calculated daily energy requirement in five of seven patients with malabsorption; in three of these five subjects the combination of decreased energy intake and increased FE loss produced negative energy balance, while in the remaining two patients malabsorption alone caused negative energy balance. Inadequate metabolizable energy in these five patients was associated with weight loss and protein-energy malnutrition. The usual clinical laboratory tests applied to the study of malabsorption, including fecal fat, fecal nitrogen, and stool weight, were poor predictors of FE loss. These tests were also of limited value in assessing the effects of dietary modification on energy malabsorption. Contrastingly, bomb calorimetry provided a simple and accurate alternative in quantitatively assessing FE loss in the patient with malabsorption.

Calorimetry↗
PubMed1980

Weekly cis-diamminedichloroplatinum(II): active third-line chemotherapy in ovarian carcinoma--a preliminary report.

Ten evaluable patients with progressive ovarian adenocarcinoma received third-line chemotherapy consisting of weekly cisplatin (cis-diamminedichloroplatinum[II]) at a dose of 1 mg/kg weekly for a maximum of 6 weeks followed by 60 mg/m2 every 3 weeks. There was no life-threatening toxicity. Seven patients (70%) achieved an objective partial response. This is the highest response rate achieved, to date, by third-line chemotherapy in women with advanced ovarian adenocarcinoma. Weekly cisplatin therefore warrants a trial as first-line therapy.

Adenocarcinoma↗
PubMed1972

Metabolic effects of human growth hormone and of estrogens in boys with Duchenne muscular dystrophy.

Metabolic balance studies were conducted in seven boys with Duchenne-type muscular dystrophy, and in six normal boys of similar age, during a 12 day control period and during a 12 day period of treatment with human growth hormone (HGH) at the following doses: 0.0168, 0.0532, and 0.168 U/kg body weight (BW)((3/4)) per day (doses A, B, and C, respectively). In five of the six normals, dose C caused positive balances in N, P, Na, and K; doses B and A had anabolic effects in two and one normal subjects, respectively. In six of the seven Duchenne cases, dose C caused negative balances of N and K, and sometimes of P. Negative balances were produced in three of the Duchenne subjects by dose B, and in one by dose A. None of the dystrophy cases exhibited an anabolic response to any dosage of HGH tested. The release of endogenous HGH in response to insulin, after 2 days' pretreatment with diethylstilbestrol, was similar in both groups of subjects. In the course of these tests, a marked anabolic effect of diethylstilbestrol in the Duchenne patients was apparent. Therefore metabolic balance studies were repeated, in both Duchenne and normal cases, during a 12 day control period and during 12 days of treatment with diethylstilbestrol (0.106 mg/kg BW((3/4)) per day). In three of the normal children, diethylstilbestrol had no effect on the elemental balances; in two cases, a retention of Na was observed. In all seven Duchenne cases, diethylstilbestrol caused positive balances in N, P, Na, and K. Ethinyl estradiol (0.0106 mg/kg BW((3/4)) per day) produced positive N, P, Na, and K balances in all three Duchenne cases tested with this agent. The data show that exogenous HGH causes a catabolic effect in boys with Duchenne dystrophy. These patients are hyperresponsive to the anabolic effect of diethylstilbestrol. The latter phenomenon may reflect the inhibitory effect of estrogen upon the peripheral actions of these boys' endogenous HGH.

Adolescent↗
PubMed1971

Observations on the responsiveness of human subjects to human growth hormone. Effects of endogenous growth hormone deficiency and myotinic dystrophy.

The effect of human growth hormone (HGH) on the N, P, Na, and K balance, and on the body weight (BW) of three groups of subjects was measured. In group I were nine cases (age 6-69) with HGH deficiency; in group II, eight cases (age 9-79) with normal endogenous HGH; in group III, four cases with myotonic dystrophy (age 45-51). After a 7 day control period, the hormone was administered for 7 days. Each subject was tested with three doses of HGH: dose A, 0.0168 U/kg BW(3/4) per day; dose B, 0.0532 U/kg BW(3/4) per day; dose C, 0.168 U/kg BW(3/4) per day. In group I, the responsiveness to HGH declined with age. Two subjects aged 6 yr responded to all three doses of HGH with positive balances in N, P, Na, and K and increases in BW. At ages 15-17, responses were obtained only to doses B and C in three cases, and only to dose C in two cases. Two subjects, aged 42 and 69, responded only to dose C. Not only did the threshold dose increase with age in group I, but the magnitude of the responses declined with age as well.Patients of group II were less responsive to all doses of HGH than were patients of group I at comparable age. None responded to dose A or dose B. All responded to dose C, but the increments in balances and in BW stimulated by this dose were only one-third to one-half as great as in HGH-deficient subjects of similar age. Three patients of group III responded to all three doses of HGH, and one responded to doses B and C. The responses were similar in magnitude to those in the 6-yr old HGH-deficient children, and greater than those in all other subjects studied. These data show that responsiveness to exogenous HGH rises with deficiency of endogenous HGH, and that individuals with myotonic dystrophy are hyperresponsive to exogenous HGH.

Adolescent↗