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Biomedical subjects

W Aziz

Publications and source records attributed to W Aziz.

9 recordsLinked to original sources
PubMed2005

Application of threshold-based acceleration change index (TACI) in heart rate variability analysis.

Heart rate variability (HRV) analysis is a non-invasive and reliable means to assess an autonomic nervous system (ANS) function. Heart rate is a non-stationary signal that may contain indicators of current diseases and sometimes warnings about impending diseases. In this paper, we have proposed the threshold-based acceleration change index (TACI) for HRV analysis, which is calculated from the sign of differences of RR time series characterizing the dynamics of threshold crossings. It was found that TACI is robust in classifying various groups under different physiological and pathological conditions. We have studied the behavior of TACI for simulated time series (uncorrelated random data, sinusoidal time series and logistics map time series) and its robustness in the presence of artifacts for RR time series. The performance of TACI is evaluated for classifying normal sinus rhythm (NSR), congestive heart failure (CHF) and atrial fibrillation (AF). An unpaired Student's t-test was used to check significant differences between these groups and the degree of separation between these groups was quantified by using the area of a receiver operator curve.

Atrial Fibrillation↗
PubMed1999

Blood flow in a chronic entrapment neuropathy model in the rabbit sciatic nerve.

A model of chronic entrapment neuropathy in the rabbit sciatic nerve was developed to try to elucidate the pathogenesis of chronic nerve entrapment. A non-compressive Silastic cuff was wrapped around the nerve at the mid-thigh level in eight rabbits. A sham operation that only elevated the sciatic nerve was performed in seven control rabbits. Six months later, the blood flow in the cuffed and the control sciatic nerves was determined with intra-arterially injected microspheres. Blood flow was significantly reduced in the entrapped nerve, compared to control nerves, but only in the segment proximal to the cuff. After surgical release of the cuff, the blood flow significantly increased in the proximal segment. This suggested that decreased blood flow may occur, but not necessarily at the site of nerve entrapment. Nerve conduction velocity changes were also consistent with an entrapment neuropathy. However, there were no significant quantitative morphometric changes at the nerve entrapment site, that is, in myelin thickness/nerve diameter ratio, distribution of axon sizes, and mean nerve fiber diameter. This indicates that only a mild entrapment was created.

Animals↗
PubMed1998

Avulsion injuries of the thumb: survival factors and functional results of replantation.

Twenty-seven cases of replantation for avulsion injuries of the thumb from 1979 to 1987 were analyzed retrospectively. Inclusion criteria required all thumbs to have tendinous attachments (either the extensor pollicis longus or the flexor pollicis longus) to the amputated part. Thirteen replants survived for an overall survival rate of 48%. Avulsions at or proximal to the metacarpophalangeal joint had a survival rate of 83% compared with a 38% survival rate distal to the metacarpophalangeal joint. This difference was not statistically significant. Of the 13 patients with surviving replanted thumbs, 11 (85%) achieved protective sensation only and 2 attained a two-point discrimination <10 mm. Of the 13 replanted thumbs that survived, 7 were treated with primary arthrodesis, 4 at the level of the interphalangeal joint and 3 at the metacarpophalangeal joint. The other 6 thumbs were treated with primary or secondary tendon transfers. In a literature review of thumb avulsion injuries, survival rates range from 26% to 100%. In this study, tendon transfers and primary arthrodesis were useful adjuncts in the management of thumb avulsions, and the majority of patients with successfully replanted thumbs attained protective sensation only. Larger studies are needed to better define statistically significant relationships affecting replantation survival.

Adolescent↗
PubMed1997

Renal failure associated with hepatitis C virus infection. Improvement in renal function after treatment with interferon-alpha.

Hepatitis C virus infection can result in mixed cryoglobulinemia and associated clinical syndromes including membranoproliferative glomerulonephritis. Reports regarding the efficacy of interferon-alpha (IFN-alpha) in the treatment of patients with membranoproliferative glomerulonephritis and chronic hepatitis C infection have been inconclusive regarding improvement of renal function. We describe two patients with chronic hepatitis secondary to hepatitis C virus complicated by mixed cryoglobulinemia and membranoproliferative glomerulonephritis who developed severe renal failure which resolved after treatment with standard doses of IFN-alpha 2b.

Adult↗
PubMed1995

Stimulation of intestinal Na+/H+ exchange by cell volume changes during fasting and refeeding in rats.

Intestinal cell water was studied in rats that have been fasted then refed, two conditions that are known to decrease and increase, respectively, proliferation of the intestinal epithelium. Cell water decreased (15%) during fasting and returned to normal with refeeding. The amiloride-sensitive sodium uptake, which estimates uptake through the Na+/H+ exchange was higher in the ileum than the jejunum, but the jejunal uptake, unlike the ileal, was significantly increased in fasted/refed rats than in normally fed or fasted ones. Osmotic shrinkage of intestinal cells followed by restitution of their cell volume stimulated the Na+/H+ exchange in all of the three groups of animals, but the increase was most prominent in the fasted and the fasted/refed groups. Also, shrinkage of cultured jejunal crypt cells (IEC-6) by a hypertonic solution increased intracellular alkalinization that was inhibited by amiloride. The results provide evidence for a relationship between the change in intestinal cell size, such as that which occurs during fasting/refeeding, and the activation of the Na+/H+ antiport system. This may represent one of the signals that initiates intestinal proliferation in the fasting/refeeding state.

Amiloride↗
PubMed1991

Toe-to-thumb transfer: a new technique.

Our technique combines the advantages of two proven techniques of the wraparound flap and vascularized joint transfer while offering a more normal thumb, both functionally and cosmetically. Its advantages are as follows: 1. A more normal-looking thumb with good length 2. Preservation of motion through joint transfer 3. Maintenance of growth potential through transfer of vascularized epiphyses 4. Minimal donor-site morbidity

Adolescent↗
PubMed1990

Transfer of the trapezius for flail shoulder after brachial plexus injury.

Shoulder arthrodesis is often used to treat flail shoulder after a brachial plexus injury, but has a high complication rate and entails loss of passive mobility. We have reviewed 27 patients with brachial plexus injury treated by transfer of the trapezius to the proximal humerus at an average time from injury of 31.3 months. Pre-operatively, all 27 shoulders were subluxated, with an average abduction of 3.5 degrees. Postoperatively, shoulder abduction averaged 45.4 degrees, and subluxation was abolished. All patients were satisfied with their improvement in function. Trapezius transfer is recommended as a simple procedure that requires only a brief period in hospital, allows early rehabilitation, and gives a satisfactory outcome, while retaining passive mobility of the shoulder.

Adolescent↗
PubMedDate not supplied

Elevated plasma CD105 and vitreous VEGF levels in diabetic retinopathy.

Diabetic retinopathy is the leading cause of blindness in the industrialized world. Hyperglycaemia induces retinal hypoxia that upregulates a range of vasoactive factors which may lead to macular oedema and/or angiogenesis and hence potentially sight threatening retinopathy. In this study, we have focused on the association of CD105 and vascular endothelial growth factor (VEGF) with the development and progression of diabetic retinopathy by means of quantifying their expression in the plasma and vitreous of diabetic patients. CD105 levels were quantified in the plasma of 38 type I diabetic patients at various stages of retinopathy and 15 non-diabetic controls. In an additional cohort of 11 patients with advanced proliferative retinopathy and 23 control subjects, CD105 and VEGF were measured in the vitreous. The values were expressed as median (range) and statistical analysis was carried out using the non-parametric Mann-Whitney U test. Plasma CD105 levels were significantly increased in diabetic patients [1.8 (1.1-2.4) ng/ml] compared with non-diabetic controls [0.7 (0.3-1.8) ng/ml] (p<0.01). Plasma CD105 levels were elevated in diabetic patients with all stages of retinopathy, the highest level was observed in background retinopathy [2.3 (2.1-2.5) ng/ml] followed by proliferative retinopathy [2.1 (0.9-2.8) ng/ml] and advanced proliferative retinopathy [1.4 (0.6-1.8) ng/ml]. Vitreous contents of CD105 did not differ between controls and patients with advanced proliferative retinopathy, but vitreous levels of VEGF were elevated by approximately 3-fold in patients with advanced proliferative retinopathy [7.2 (1.90-15.60) ng/ml] compared with the control subjects [1.80 (1.10-2.210)] (p<0.01). These observations indicate that plasma levels of CD105 and vitreous levels of VEGF are associated with diabetic retinopathy, suggesting that CD105 and the angiogenic factor VEGF may play a critical role in the development and progression of diabetic retinopathy. Further studies are required to determine whether circulating CD105 levels could serve as a surrogate marker for early stage retinopathy and for monitoring disease progression.

Antigens, CD↗