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Biomedical subjects

A Hassan

Publications and source records attributed to A Hassan.

At least 109 records · Page 6Linked to original sources
PubMed1990

Observations on the pathogenicity for sheep and goats and the transmissibility of the strain of virus isolated during the rinderpest outbreak in Sri Lanka in 1987.

The pathogenicity for sheep and goats of the virus strain that caused acute rinderpest in cattle and domestic buffalo in Sri Lanka after an interval of over 40 years has been examined. The results show that it can cause overt clinical disease in goats, but only mild or unapparent infection in sheep. The disease was transmitted from infected sheep to in-contact susceptible sheep and calves.

Animals↗
PubMed1988

Quantitation of acidosis in neonatal brain tissue using the 31P NMR resonance peak of phosphoethanolamine.

31P NMR brain spectra were obtained from piglets over a range of mild hypocarbia to severe hypercarbia (PaCO225 to 198 mm Hg). The chemical shifts of the phosphoethanolamine and inorganic phosphate were used to calculate intracellular brain pH (pHet and pHpi, respectively). Both pHpi and pHet underwent parallel significant decreases during hypercarbia, corresponding to 51 and 53% pHregulation, respectively. We conclude that the chemical shift of the phosphomonoester peak in vivo can be used to measure decreases in intracellular pH in neonatal brain.

Acidosis↗
PubMed1988

Effects of repeated ischemia on cerebral blood flow and brain energy metabolism.

To determine if cerebral blood flow (CBF) and cerebral metabolic alterations during partial ischemia are affected by a prior interval of ischemia, 13 neonatal piglets were studied during two successive protocols (termed A and B), each consisting of an interval before, during and after partial ischemia induced by hypotension. Piglets were studied with either microspheres (n = 6) to measure CBF and calculate cerebral uptake of O2 and glucose or 31P nuclear magnetic resonance spectroscopy (n = 6) to measure intracellular pH (pHi) and cerebral phosphorylated metabolites. One piglet was used to determine time effects. Control values of all variables were similar during protocol A and B. In each protocol hypotension was associated with similar reductions in CBF and cerebral O2 uptake but cerebral glucose uptake differed (0.10 +/- 0.05 vs 0.05 +/- 0.02 mmol.min-1.100 g-1 during hypotension of A and B, respectively, p less than 0.05). During hypotension of protocol A and B similar changes in phosphorylated metabolites and pHi occurred and were characterized by a reduction in pHi, phosphocreatine and adenosine triphosphate and an increase in inorganic phosphate. Changes in phosphate metabolites and pHi were reversible within 25 min following hypotension in both protocols. Thus, changes in CBF, cerebral O2 uptake, pHi and cerebral energy metabolism are similar during repeated episodes of partial ischemia. However, differences in cerebral glucose uptake in protocol A and B raise the possibility that the balance between energy production and utilization is altered, or alternative substrates are metabolized or enzymatic activity in the glycolytic pathway is changed.

Animals↗
PubMed1988

Intracellular pH, lactate, and energy metabolism in neonatal brain during partial ischemia measured in vivo by 31P and 1H nuclear magnetic resonance spectroscopy.

Sequential 31P and 1H nuclear magnetic resonance spectra were measured for neonatal piglets (n = 7) to determine the relationship between brain intracellular pH (pHi), lactate, and phosphorylated energy metabolites during partial ischemia. Simultaneous determinations of arterial and cerebral venous blood gases, pH, O2 content, and plasma concentrations of glucose and lactate were also made. Ischemia, induced by bilateral carotid artery ligation plus hemorrhagic hypotension for 35 min, resulted in variable reductions in ATP, phosphocreatine, and increases in Pi, H+, and lactate relative to control levels. In four piglets, whose arterial blood glucose rose above control, brain lactate exceeded 20 mumol g-1 with corresponding decreases in pHi of greater than 0.7 units compared to control levels. The extents of brain acidosis and lactosis showed a strong linear correlation with each other (r = 0.94). Maximal changes in brain lactate, pHi, and ATP at the end of ischemia showed significant positive linear correlations with the control levels of arterial blood glucose, but did not correlate with arterial glucose or arterial cerebral-venous glucose difference values during ischemia. The relationship between pHi and buffer base deficit was comparable to results reported for adult animals up to 20 mumol ml-1. However, in contrast to models proposed for adult brain, the continued linear relationship between pH and higher buffer base levels is most consistent with a theoretical model that assumes the presence of weak acid buffers with pKa values from 6.7 to 5.2.

Adenosine Triphosphate↗
PubMed1986

Blood flow in the skin of the foot related to posture in diabetes mellitus.

Normal healthy subjects show a reflex rise in precapillary resistance in the skin of the foot when they rise from lying to standing. To investigate the integrity of this reflex in patients with diabetes mellitus blood flow in the plantar region of the big toe was measured, using a laser Doppler flowmeter. The responses of diabetic patients with and without peripheral sensory neuropathy and healthy control subjects matched for age and sex were studied, with the foot at heart level and the foot passively lowered to 50 cm below the heart. In normal subjects mean blood flow recorded during the third to fourth minute of dependency fell to 18.1 (SD 11.9)% of the preceding resting flow determined with the foot at heart level. In the diabetic patients without neuropathy blood flow fell to 28.9 (18.6)% of the preceding resting flow. In the diabetic patients with neuropathy blood flow fell to 53.5 (23.7)% of the preceding resting flow, which was significantly different from the value achieved by the diabetics without neuropathy (p less than 0.02) and the healthy controls (p less than 0.002). Six normal subjects were indirectly heated to release sympathetic tone and achieve the same mean skin temperature of the foot as the diabetic patients with neuropathy, and blood flow fell to 38.7 (24.3)% of the preceding resting flow, a value not significantly different from the response seen in the patients with neuropathy. These findings suggest that the postural control of blood flow in the foot is disturbed in patients with diabetic neuropathy, and this disturbance is compatible with a loss of sympathetic vascular tone. The resultant hyperperfusion on dependency may account for the oedema seen in some patients with neuropathy and may also act as a stimulus for the thickening of capillary basement membranes.

Adolescent↗
PubMed1985

Growth and biochemical changes in mammary glands of ewes from 1 to 18 months of age.

Growth and development of the mammary gland of ewe lambs was characterized by changes of various biochemical constituents. Mammary glands were removed from 49 ewe lambs ranging between 1 and 18 mo of age, weighed before and after trimming, and samples of the trimmed glands were fat extracted and dried. The dried fat-free tissues were weighed, ground, and analyzed for nucleic acids, nitrogen, sodium, potassium, and chloride contents. Fresh samples were used for glycogen determination. Trimmed weight of mammary glands increased rapidly after the 9th mo of age. The pattern was similar for nucleic acid content of mammary glands. Dry matter and fat contents of mammary glands increased up to the 9th mo, fat decreased thereafter, and dry matter remained constant. Protein content was low up to the 9th mo and increased thereafter. Sodium and glycogen content in mammary glands increased, but potassium decreased linearly from 1 to 18 mo of age. Allometric growth of mammary tissue started at about 3 mo of age, before onset of puberty at 8 mo of age, but intense mammary metabolic activity started only after the ewe attained puberty.

Aging↗
PubMed1983

The effect of seminal sperm concentration on sperm transport in the reproductive tract of female rabbits treated with progesterone or diethylstilbestrol.

Forty-two mature Baladi female rabbits were used in a randomized 3x2 factorial experiment to determine the effects of three treatments (control, progesterone injection: 2 mg/doe and DES injection: 0.1 mg/doe) and two semen sperm cell concentrations (1x10(6) and 60x10(6) sperm/0.25 ml semen on sperm transport and distribution in the female reproductive tract. The injections were given for three consecutive days after which rabbits were injected with 5 IU HCG and inseminated with 0.25 ml semen. The does were sacrificed 10 hrs after insemination and the sperm were recovered and counted from the oviducts, uterine horns, cervices and vagina. Total spermatozoa recovered was high when rabbits were inseminated with 60x10(6) sperm as compared to those inseminated with 1x10(6) sperm. When rabbits were injected with progesterone or DES, the number of sperm recovered relative to the total number of sperm inseminated was high in rabbits inseminated with 1x10(6) sperm, in comparison to those inseminated with 6x10(6) sperm. The number of sperm recovered was highest from cervix which was followed by vagina, uterus and oviducts. DES increased the number of the total sperm recovered while progesterone decreased the number as compared to control. This trend was also observed within the different segments of the reproductive tract and with groups inseminated with 1x10(6) or 60x10(6) sperm/0.25 ml semen. The effect of DES was more obvious with does inseminated with low sperm numbers. Significant correlation coefficients were found between the sperm numbers recovered in the uterus and oviducts and in the cervix and uterus of all groups of rabbits.

Journal Article↗
PubMed1983

Effects of unilateral ovariectomization on the numbers of sperm in the oviducts, uterus and cervix of rabbits.

The experiment was designed to determine the effect of removing one of the rabbits' ovaries on the numbers of sperm in the oviducts, uterine horns and cervices. The possible relationship between the anatomical asymmetry of the two sides of the reproductive tract and the distribution of sperm within different segments of the tract was also studied. Fifteen female rabbits were used; five were kept intact as the control group, five were right ovariectomized and five were left ovariectomized. All rabbits were injected with 50 IU HCG to induce ovulation and then inseminated with 60x10(6) sperm in 0.25 ml semen. Does were inseminated one month after unilateral ovariectomy. Animals were sacrificed 10 hrs later and sperm was recovered from the right and left oviducts, uterine horns and cervices. Unilateral ovariectomy significantly reduced the total numbers of sperm recovered as compared with intact does. The total numbers of sperm recovered from each of the two sides of the tract were not affected by the site of the removed ovary. Sperm numbers were high in the cervices of all groups and then decreased gradually in the upper segments of the tract. Sperm numbers that reached the oviduct of the intact rabbits were greater than those of both unilateral ovariectomized groups of rabbits. Differences between the length of the left and right cervices and uterine horns were not significant, but the right oviduct was significantly longer than the left oviduct.

Journal Article↗
PubMed1982

The endogenous stages of Sarcocystis cameli (Mason, 1910).

The endogenous stages of Sarcocystis cameli (Mason, 1910) in the small intestine of dogs are described. These stages are mainly in the posterior third of the small intestine. They were observed only in the lamina propria of the distal third of the villi. There was no schizogonic process. Micro and macrogamonts were differentiated 18 h p.i. The first zygote was observed 24 h later. Unsporulated oocysts were found 30, 36, 42, 48 h and 4 days p.i. The oocysts started sporulation on the 5th day p.i. Completely sporulated oocysts were formed 8 days p.i.

Animals↗
PubMed1981

Mercury poisoning in Nicaragua: a case study of the export of environmental and occupational health hazards by a multinational corporation.

Pennwalt Inc., a multinational chemical and pharmaceutical firm based in the United States, operates a chloralkali plant in Managua, Nicaragua. This plant utilizes elemental mercury in the production of chlorine and caustic soda for markets throughout Central America. The plant was recently found to be contaminating the waters of Lake Managua (on which the plant is located) with 2 to 4 tons of inorganic mercury effluent per year-over 40 tons in the 13-year history of the plant. Examination of the 152 workers employed in the plant showed that 56(37 percent) were suffering symptoms and signs of mercury poisoning, including tremors (in 45), memory and attention deficits (in 45) and paresthesias (in 52). Levels of airborne mercury vapor in the plant were found to range as high as 600 microgram/m3. (The airborne standard set by the U.S. Occupational Safety and Health Administration is 100 microgram/m3.) Workers in the plant had never been alerted to the hazards of mercury. The plant was found to be in deteriorated condition, with no recent investments in maintenance or modern safety equipment. It is reported that the parent corporation, Pennwalt, has been withdrawing capital from the operation (and from Nicaragua) since the fall of the Somoza regime.

Air Pollutants, Occupational↗