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Biomedical subjects

G Abraham

Publications and source records attributed to G Abraham.

At least 73 records · Page 4Linked to original sources
PubMed1996

Different vascular responses to subpressor angiotensin II administration in the mesenteric and renal circulation of rats.

Administered in small doses, angiotensin II (ANG II) potentiates its own pressor responses (autopotentiation). In the present study, we investigated whether potentiation of vasoconstrictor responses in the mesenteric and renal circulation accounted for the autopotentiation of pressor responses. Male Sprague-Dawley rats, 350 to 400 g, were infused with 200 ng/kg/min ANG II intraperitoneally for 7 to 10 days. Control rats were fitted with an osmotic minipump containing vehicle only. Vascular responses to ANG II, norepinephrine (NE), arginine vasopressin (AVP) and nerve stimulation were measured in the mesenteric and renal circulation of rats. In ANG II-treated rats: 1) tail systolic BP was 4 mm Hg higher than in controls (P = NS); 2) mesenteric vascular responses to ANG II (P < .002) and nerve stimulation (P = .03) were increased, and those to NE and AVP were unchanged; and 3) renal vascular responses to nerve stimulation were reduced (P < .02), and those to ANG II, NE, and AVP were unchanged. Thus, we demonstrated autopotentiation of vascular responses to ANG II in the mesenteric, but not the renal circulation. An interaction between ANG II and sympathetic activity may explain these differences in regional vascular responses. Regional hemodynamic measurements may provide important clues to pathogenetic mechanisms in hypertension.

Angiotensin II↗
PubMed1996

Continuous ambulatory peritoneal dialysis.

Continuous ambulatory peritoneal dialysis (CAPD) was used as renal replacement therapy in 55 patients for 666 patient months. Thirty five patients had Type II diabetes. They ranged in age from 1-83 years. Majority of the patients were above 50 years of age who could not be transplanted due to various comorbid conditions. The incidence of peritonitis was 1 episode every 20 patient months. Twenty five patients dropped out during the observation period. The major cause of drop-out was death due to underlying coronary artery disease. Three patients underwent renal transplantation.

Adolescent↗
PubMed1995

Pressor and subpressor angiotensin II administration. Two experimental models of hypertension.

Administered dose is an important determinant of the type of hypertension produced by angiotensin II. With chronic administration of pressor doses, there is salt and water retention and expansion of extracellular fluid volume, and the pressure-natriuresis curve is shifted to higher pressures. Important compensatory mechanisms, including resetting of baroreceptors, de novo synthesis of vasodilator prostaglandins, and atrial natriuretic factor release, are triggered by the acute rise of blood pressure. Histologic evidence for vascular injury confounds the interpretation of findings. When angiotensin II is administered in initially subpressor doses, the rise of blood pressure is gradual, there are no detectable changes in salt and water balance, and compensatory mechanisms do not seem to be activated. Autopotentiation of pressor and vasoconstrictor responses by angiotensin II is the characteristic feature of the early stages of hypertension induced by small doses of angiotensin II. Trophic stimulation of vascular tissue, in particular restructuring of extracellular matrix, precedes and may, therefore, be the mechanism responsible for the hemodynamic changes. The pressor and subpressor models of angiotensin II-induced hypertension draw attention to the relative importance of renal and extrarenal mechanisms in the pathogenesis of hypertension. The long-term administration of initially subpressor doses of angiotensin II mimics the development of human hypertension to a greater extent than does the administration of pressor doses.

Angiotensin II↗
PubMed1995

Are the renal effects of lithium modified by frequency of administration?

It has been claimed that the unwanted effects and toxicity of lithium can be minimized by changes in the dosing schedules. Twenty consecutive psychiatrically stable patients were investigated in a cross-over study to determine whether renal function and other biochemical tests change significantly with changes from once to twice or multiple doses per day or vice versa. There were no significant differences between the 3 study conditions on the mood rating scales or a side effect scale (UKU). Urine volume, test of renal function and other biochemical and hematological indices were similar in all study conditions. We thus conclude that dosing strategy does not consistently affect renal function in lithium-treated patients.

Adult↗
PubMed1995

Recommended biocontainment features for research and diagnostic facilities where animal pathogens are used. First International Veterinary Biosafety Workshop.

Recommendations are presented for the minimum structural components, special utilities, installations, and other design and operational features which define a microbiologically-secure animal containment facility. These biocontainment parameters are expected to enable the safe housing and handling of livestock and poultry infected with pathogenic agents. Physical testing and certification requirements for commissioning such facilities are described. Such a facility will minimise personnel exposure to infectious agents, limit cross-contamination between experiments, minimise horizontal transmission between research animals, and reduce the likelihood of pathogenic agents being released to the outside environment.

Animals↗
PubMed1994

Computed tomographically guided biopsy of the spine.

STUDY DESIGN: Efficacy of the percutaneous biopsy of the spine under computed tomographic guidance was investigated. Seventy-five patients, ranging in age from 7 to 72 years, underwent this procedure. OBJECTIVES: To determine the usefulness of computed tomographically guided biopsies in the treatment of patients with spinal disorders. SUMMARY OF BACKGROUND DATA: The results of 68 biopsies (90.6%) were judged to be accurate insofar as the samples of tissue obtained could be diagnosed as specific types of neoplasm, infective lesions, reactive lesions of nonspecific type, or normal bone. METHODS: Biopsies that yielded a specific abnormality were categorized as true positives. The "normal" biopsies were followed for 6-18 months and were then deemed true negatives. Nondiagnostic ones were considered false negatives. RESULTS: The results are acceptable with an accuracy rate of 90.6%. It is a safe and simple procedure with a short learning curve. CONCLUSIONS: Computed tomographically guided biopsy of the spine is recommended as a procedure of choice, especially in cervical and thoracic lesions. Computed tomography is superior to fluoroscopy when dealing with small, deep-seated lesions especially in the cervical and thoracic regions and with lesions picked up on bone scan only, radiographs being negative. Needle biopsy under computed tomographic guidance is safe and precise.

Adolescent↗
PubMed1994

Peste des petits ruminants in Ethiopian goats.

An outbreak of disease characterised by fever, ocular and nasal discharge, coughing and sneezing, oral necrosis, diarrhoea, enteritis and pneumonia in goats was shown by the use of specific cDNA probes to have been peste des petits ruminants, confirmed for the first time in Ethiopia. Both morbidity and mortality rates were high in goats but sheep were not affected.

Animals↗
PubMed1994

Foot-and-mouth disease in Ethiopia from 1988 to 1991.

During the period 1988 to 1991 samples from 16 foot-and-mouth disease outbreaks in Ethiopia were examined at the National Veterinary Institute, Ethiopia, and at the FAO World Reference Laboratory for Foot-and-Mouth Disease, UK. Typing of the virus responsible was possible in 13 of these outbreaks representing 10 separate disease events; 8 of these were caused by serotype O and 2 by serotype SAT2. This is the first record of the presence of serotype SAT2 foot-and-mouth disease virus in Ethiopia. In contrast to earlier studies serotypes A and C were not detected.

Animals↗
PubMed1994

Reconstruction of the quadriceps apparatus following open injuries to the knee joint using pedicled gastrocnemius musculotendinous unit as bridge graft.

The objectives of treating open knee joint injuries with disruption of the distal quadriceps mechanism are to ensure rapid wound healing and to restore joint function. For this it is necessary to provide soft tissue cover, control infection, restore full extension of the knee by reconstruction of the extensor apparatus and prevent joint stiffness by early mobilisation. Two cases are presented where the gastrocnemius (medial half) musculotendinous unit has been used to reconstruct, in one stage, the extensor apparatus and at the same time to provide soft tissue cover.

Child↗
PubMed1994

Autopotentiation of pressor responses by subpressor angiotensin II in rats.

The mechanisms whereby the continuous administration of initially subpressor doses of angiotensin II (ANG II) leads to pressor hyperresponsiveness and gradual development of hypertension were investigated. Male Sprague-Dawley rats (350 to 400 g) were given ANG II intraperitoneally, 200 ng/kg/min, for 24 h, 7 to 10 days, or 6 weeks. Vehicle-infused rats were controls. Pressor responses to incremental doses of ANG II, norepinephrine (NE), and serotonin were measured in chloralose-anesthetized rats, before and after neurohumoral blockade, and the main findings were confirmed in awake, free-moving rats with implanted catheters. Pressure responses to ANG II and NE were also measured in the isolated, pump-perfused mesenteric circulation of rats after 7 to 10 days of ANG II or sham infusion. Compared with control rats, there were no hemodynamic changes in ANG II-treated rats at 24 h. After 7 to 10 days of ANG II treatment, tail systolic blood pressure rose by 13 mm Hg (P < .01) and pressor responses to ANG II (P < .01) but not to NE or serotonin were increased. Pressor hyperresponsiveness was due in part to potentiation of vascular responses because pressure responses to ANG II (P < .002) but not to NE were also increased in the mesenteric circulation of ANG II-treated rats. By 6 weeks, mild hypertension was well established in ANG II-treated rats and pressor responses were increased to both ANG II (P < .05) and NE (P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Single-stage reconstruction of soft-tissue defects including the Achilles tendon using the dorsalis pedis arterialized flap along with the extensor digitorum brevis as bridge graft.

Open ruptures of the Achilles tendon with loss of the tendon and the overlying skin are very difficult to treat. They pose the problems of (1) combating infection, (2) providing soft-tissue cover, and (3) bridging the gap in the tendon. They are generally managed as multi-staged procedures. Once the infection is brought under control with debridement and antibiotics, skin cover is provided by local transposition flaps, distant pedicle flaps, or free-tissue transfer with microvascular anastomoses. The tendon itself is repaired later by one of the conventional techniques. More recently, composite free-tissue transfers repairing the skin and tendon in a single stage have been reported. We describe a simple and very reliable procedure using a dorsalis pedis island flap which provides a vascularized, innervated musculotendinous unit (i.e., extensor digitorum brevis) to bridge the gap in the Achilles tendon and thin, mobile skin and fascia to close the defect in the skin. Two cases are presented, including the technical details, advantages, and limitations of this procedure.

Achilles Tendon↗
PubMed1994

Accessory soleus muscle: a problem of awareness.

Reports of accessory soleus muscle are rare, perhaps as a result of it often remaining unrecognized. It presents as a swelling behind the ankle and may be mistaken for a tumour or inflammatory lesion, as occurred in the first of a series of three cases. The other two were incidental findings, one in a 30 year old man with an open tibial fracture and the other in a 9 month old child with a club foot. Patients present with either pain or a diagnostic problem. When large, it may make wearing of footwear difficult. Computerized tomography with electromyography enables confirmation of the diagnosis. Pain is relieved by epimysiotomy and when encountered incidentally during surgery, incision of the epimysium is all that is needed. Excision of the muscle may be considered only if wearing of footwear is difficult. The significance of its presence in a case of club foot is unknown. Disinsertion of its insertion was all that was required to obtain surgical correction of the deformity in the present case. Awareness of the condition will prevent unnecessary surgery in asymptomatic cases.

Adult↗
PubMed1994

Stimulation of vascular glycosaminoglycan synthesis by subpressor angiotensin II in rats.

The vascular trophic effects of angiotensin II (Ang II) in small doses may precede its hypertension-producing effect, and de novo synthesis of components of extracellular matrix may be a requirement for Ang II-stimulated growth. In the present study, therefore, the incorporation of 35SO4 into glycosaminoglycans (synthesis) of aorta and bladder wall of young adult, male Sprague-Dawley rats was measured ex vivo after 48 hours of Ang II administration at two dose levels, 100 and 200 ng.kg-1.min-1 IP. Vehicle-infused rats served as controls. Compared with controls, systolic blood pressure was unchanged in rats receiving 100 ng.kg-1.min-1 Ang II and rose by 13 mm Hg (P < .05) in rats receiving the 200-ng.kg-1.min-1 dose. In Ang II-treated rats, glycosaminoglycan synthesis of the aorta was increased by 20% (P < .05) and 52% (P < .005) at the two dose levels, respectively. Glycosaminoglycan synthesis of bladder smooth muscle was also increased in Ang II-treated rats (P < .01), but the response was not dose dependent. By 7 to 10 days of Ang II administration (200 ng.kg-1.min-1), glycosaminoglycan synthesis of aorta returned toward baseline (P < .10, > .05). The rate of synthesis of subtypes of glycosaminoglycans in the aorta was proportionately increased by Ang II. The early occurrence, magnitude, and arterial pressure independence of Ang II-induced glycosaminoglycan synthesis suggest that restructuring of extracellular matrix may play an important role in both the trophic and hypertension-producing action of Ang II.

Amino Acid Sequence↗