Biomedical subjects

D Schulman

Publications and source records attributed to D Schulman.

13 recordsLinked to original sources

PubMed2006

Active Ras-induced effects on skeletal myoblast differentiation and apoptosis are independent of constitutive PI3-kinase activity.

23A2 myoblasts expressing GAP-resistant, constitutively active G12V:H-Ras (A2:G12V:H-Ras myoblasts) display a transformed morphology and do not undergo mitogen-deprivation-induced differentiation or the associated apoptosis. To determine the phenotype induced by F156L:H-Ras, a constitutively active mutant with enhanced nucleotide exchange activity rather than impaired GAP-stimulated GTPase activity, myoblast cell lines were established that stably express F156L:H-Ras at levels of H-Ras comparable to the A2:G12V:H-Ras myoblasts. These A2:F156L:H-Ras myoblast cell lines do not possess a transformed morphology, and while differentiation and apoptosis are impaired, these processes are not abrogated as in the A2:G12V:H-Ras myoblasts. Surprisingly, while expression of either G12V:H-Ras or F156L:H-Ras results in constitutive signaling through PI3-kinase, only cells expressing G12V:H-Ras additionally possess constitutive signaling through MAPK, and NFkappaB. Pharmacological abrogation of the Ras-induced constitutive PI3-kinase signal, however, is not responsible for the impaired differentiation or apoptosis in either A2:G12V:H-Ras myoblasts or A2:F156L:H-Ras myoblasts. Thus, our data suggest that a pathway distinct from those that signals through MAPK, NFkappaB or PI3-kinase is responsible for the impaired differentiation and apoptosis in 23A2 skeletal myoblasts expressing constitutively active Ras.

Animals↗

PubMed2002

A comparison of liquid hot water and steam pretreatments of sugar cane bagasse for bioconversion to ethanol.

Sugar cane bagasse was pretreated with either liquid hot water (LHW) or steam using the same 25 l reactor. Solids concentration ranged from 1% to 8% for LHW pretreatment and was > or = 50% for steam pretreatment. Reaction temperature and time ranged from 170 to 230 degrees C and 1 to 46 min, respectively. Key performance metrics included fiber reactivity, xylan recovery, and the extent to which pretreatment hydrolyzate inhibited glucose fermentation. In four cases, LHW pretreatment achieved > or = 80% conversion by simultaneous saccharification and fermentation (SSF). > or = 80% xylan recovery, and no hydrolyzate inhibition of glucose fermentation yield. Combined effectiveness was not as good for steam pretreatment due to low xylan recovery. SSF conversion increased and xylan recovery decreased as xylan dissolution increased for both modes. SSF conversion, xylan dissolution. hydrolyzate furfural concentration, and hydrolyzate inhibition increased, while xylan recovery and hydrolyzate pH decreased, as a function of increasing LHW pretreatment solids concentration (1-8%). These results are consistent with the notion that autohydrolysis plays an important. if not exclusive, role in batch hydrothermal pretreatment. Achieving concurrently high (greater than 90%) SSF conversion and xylan recovery will likely require a modified reactor configuration (e.g. continuous percolation or base addition) that better preserves dissolved xylan.

Biodegradation, Environmental↗

PubMed2001

The value of taking an 'ethics history'.

OBJECTIVES: To study the value of taking an ethics history as a means of assessing patients' preferences for decision making and for their relatives' involvement. DESIGN: Questionnaire administered by six junior doctors to 56 mentally competent patients, admitted into general and geriatric medical beds. SETTING: A large district general hospital in the United Kingdom. MAIN MEASURES: To establish whether patients were adequately informed about their illness and whether they minded the information being communicated to their relatives. To establish their preference regarding truthful disclosure and participation in decision making with risk attached. To establish whether they wished to be involved in CPR decision making, and if not, who should make the decision. To establish whether they knew of living wills and whether they had any advance directives. RESULTS: Twenty-four (43%) were inadequately informed of their illness. Forty-six (82%) said they would want to know were something serious to be found. Twenty-eight (50%) wanted to make their own decision if requiring risky treatment and 11 (20%) wanted family members involved. Thirty-one (55%) wanted to make a cardiopulmonary resuscitation (CPR) decision and five of these decisions differed from those made by the doctors. Twenty-five (45%) preferred the doctors to decide. Eleven (20%) of the patients had heard of living wills but only one had executed such a will. Seven (13%) of the patients wished to provide advance directives. Three (5%) did not find the history taking helpful but none were discomforted. CONCLUSION: Taking an ethics history is a simple means of obtaining useful information about patients' preferences.

Advance Care Planning↗

PubMed2001

Effect of aging on the ability of preconditioning to protect rat hearts from ischemia-reperfusion injury.

Ischemic preconditioning (IP) reduces infarct size in young animals; however, its impact on aging is underinvestigated. The effect of variations in IP stimuli was studied in young, middle-aged, and aged rat hearts. Isolated hearts underwent 35 min of regional ischemia and 120 min of reperfusion. Hearts with IP were subjected to either one ischemia-reperfusion cycle (5 min of ischemia and 5 min of reperfusion per cycle) or three successive cycles before 35 min of regional ischemia. Additional studies investigated the effects of pharmacological preconditioning in aged hearts using the adenosine A(1) receptor agonist 2-chloro-N(6)-cyclopentyladenosine, the protein kinase C analog 1,2-dioctanoyl-sn-glycerol, and the mitochondrial ATP-sensitive potassium (K(ATP))-channel opener diazoxide. Infarct sizes indicated that the aged rat heart could not be preconditioned via ischemic or pharmacological means. The middle-aged rat heart had a blunted IP response compared with the young adult (only an increased IP stimulus caused a significant reduction in infarct size). These results suggest that there are defects within the IP signaling cascade of the aged heart. Clinical relevance is important if we are to use any IP-like mimetics to the benefit of an aging population.

Adenosine↗

PubMed1990

Evidence for gastric mucosal cell invasion by C. pylori: an ultrastructural study.

It is now generally accepted that Campylobacter pylori is closely associated with peptic ulcer disease and chronic type B gastritis. Whether C. pylori is the direct etiologic cause of either or both of these illnesses remains unclear. Possible pathophysiologic effects of C. pylori are still a matter of debate and conjecture. Utilizing a small group of patients with gastric ulcers and chronic gastritis, we examined the ultrastructural relationship between C. pylori and gastric cells. Forty-eight percent of our gastric ulcer patients and 57% of our chronic gastritis patients had C. pylori in their lower corpus mucosa. Examination with the transmission electron microscope indicated a very close proximation by C. pylori to the surface epithelial cells strongly suggesting adherence. We also describe for the first time the invasion of gastric cells by C. pylori. Although an uncommon occurrence, we had repeated observations of C. pylori invading surface epithelial cells, parietal cells, and chief cells. Most of the intracellular C. pylori were intact but other forms appearing to be degenerating organisms were also seen. We suggest that cell invasion may be one mechanism by which C. pylori causes pathologic changes in the gastric mucosa. These observations may also explain why C. pylori chronically infects gastric cells and frequently recurs after treatment.

Gastric Mucosa↗

PubMed1987

Crohn's disease of the vulva.

Vulvar involvement is an uncommon extraintestinal manifestation of Crohn's disease. A case of "metastatic" vulvar Crohn's disease occurring in a 23-yr-old woman, status post-ileocolectomy, is described. The diagnosis was established by vulvar punch biopsy, and a therapeutic response was achieved with metronidazole and prednisone. The literature on vulvar involvement with Crohn's disease is reviewed and therapeutic options are discussed.

Adult↗

PubMed1986

A nonpuerperal traumatic vulvar hematoma.

A case is presented where a nonpuerperal traumatic vulvar hematoma was initially mistaken for a Bartholin's gland duct abscess. Since the treatment may be different, the importance of clinical differentiation between these two entities is stressed. Proper management of the vulvar hematomas involves bed rest, close observation, and early surgical intervention only when absolutely necessary. Patients with significant vulvar hematomas should be hospitalized and closely followed.

Abscess↗

PubMed1978