PubMed Health⌕ Search

Biomedical subjects

S T Hussain

Publications and source records attributed to S T Hussain.

At least 19 recordsLinked to original sources
PubMed2005

The case for saphenous ablation versus simple proximal ligation.

New modalities of treatment for primary varicose veins are being increasingly used. This is because traditional stripping and sapheno-femoral junction ligation is requires a general anaesthetic and is associated with postoperative pain and bruising. This article aims to address the evidence and long-term follow up of the new surgical techniques and compare them to traditional sapheno-femoral ligation.

Humans↗
PubMed2003

Aortic aneurysm replacement with Dacron graft in a 34 year old man. How long will the graft last?

A unique case of an abdominal aortic aneurysm replacement in a young man of Caribbean descent is presented. The initial working diagnosis was of a mycotic aneurysm, which has recently shown resurgence with intravenous drug abuse. Blood tests and subsequent biopsy ruled that out. There was also a clinical suspicion of a connective tissue abnormality. Histological examination of the aneurysm, skin biopsy, and blood tests also ruled out this possibility. The graft used in this patient was from a new generation of grafts. In the absence of any studies on such grafts, there is the question of long term durability of the graft.

Adult↗
PubMed2002

Vestibular evidence for the evolution of aquatic behaviour in early cetaceans.

Early cetaceans evolved from terrestrial quadrupeds to obligate swimmers, a change that is traditionally studied by functional analysis of the postcranial skeleton. Here we assess the evolution of cetacean locomotor behaviour from an independent perspective by looking at the semicircular canal system, one of the main sense organs involved in neural control of locomotion. Extant cetaceans are found to be unique in that their canal arc size, corrected for body mass, is approximately three times smaller than in other mammals. This reduces the sensitivity of the canal system, most plausibly to match the fast body rotations that characterize cetacean behaviour. Eocene fossils show that the new sensory regime, incompatible with terrestrial competence, developed quickly and early in cetacean evolution, as soon as the taxa are associated with marine environments. Dedicated agile swimming of cetaceans thus appeared to have originated as a rapid and fundamental shift in locomotion rather than as the gradual transition suggested by postcranial evidence. We hypothesize that the unparalleled modification of the semicircular canal system represented a key 'point of no return' event in early cetacean evolution, leading to full independence from life on land.

Animals↗
PubMed2001

Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls.

Modern members of the mammalian order Cetacea (whales, dolphins and porpoises) are obligate aquatic swimmers that are highly distinctive in morphology, lacking hair and hind limbs, and having flippers, flukes, and a streamlined body. Eocene fossils document much of cetaceans' land-to-water transition, but, until now, the most primitive representative for which a skeleton was known was clearly amphibious and lived in coastal environments. Here we report on the skeletons of two early Eocene pakicetid cetaceans, the fox-sized Ichthyolestes pinfoldi, and the wolf-sized Pakicetus attocki. Their skeletons also elucidate the relationships of cetaceans to other mammals. Morphological cladistic analyses have shown cetaceans to be most closely related to one or more mesonychians, a group of extinct, archaic ungulates, but molecular analyses have indicated that they are the sister group to hippopotamids. Our cladistic analysis indicates that cetaceans are more closely related to artiodactyls than to any mesonychian. Cetaceans are not the sister group to (any) mesonychians, nor to hippopotamids. Our analysis stops short of identifying any particular artiodactyl family as the cetacean sister group and supports monophyly of artiodactyls.

Animals↗
PubMed2001

An observational study of 256 cases of vascular trauma in the north western province of Pakistan.

During the past 10 years Peshawar has dealt with increasing casualties with penetrating trauma inflicted by a wide variety of missiles. The aim of this study was to assess whether delay in arrival and mode of presentation affects the outcome of patients with penetrating vascular trauma. Prospective data were collected on 256 vascular injuries in 248 patients (median age, 29 years; range, 7-60 years) between January 1995 and June 1998. Early presentation (group A, 55 cases, < 12 h) was compared with late presentation (group B, 201 cases, > 12 h). The majority of injuries (93%) were caused by fire-arms. Arterial injuries accounted for 71% of the total, venous injuries accounted for 10% and 19% were mixed. The site of injury was the lower limb (61%), upper limb (32%), abdominal cavity (5%) and neck (2%). Patients presented with absent pulses (56%), haemorrhage (46%), false aneurysms (8%), A-V fistula (5%) and 11% presented with more than one sign. There were significantly more lower limb amputations in group A than group B (23% versus 5%; P < 0.05), with fractures having a positive association with lower limb amputations (odds ratio, 0.32; 95% CI, 0.13-0.94; P < 0.05). Group A had a higher mortality than group B (18% versus 7%; P < 0.05). This study shows that patients with vascular trauma can be managed successfully with clinical assessment alone. Patients with fractures were more likely to suffer eventually from lower limb loss. Due to self-selection, arrival at the hospital less than 12 h after sustaining vascular injury was associated with a higher mortality than those presenting after 12 h.

Adolescent↗
PubMed1997

Blood flow measurements in lower limb arteries using duplex ultrasound.

The increase in blood flow in exercise is to provide more oxygen to tissues. The kinetics of flow at the common femoral artery bifurcation were established in normal subjects together with its relationship with oxygen uptake. Furthermore, the changes in flow were evaluated in patients undergoing superficial femoral artery angioplasty. After a known anaerobic test (Wingate test), normal subjects underwent a preferential increase in profunda femoris artery flow (ninefold increase), compared with superficial femoral artery flow (fourfold increase), indicating predominantly thigh exercise. The relationship between oxygen uptake and lower limb blood flow was studied before, during and after moderate intensity exercise. Oxygen uptake was measured by mass spectrometry and assessed by breath-by-breath analysis. The rate of increase for limb blood flow, as indicated by the time constant, was faster (28.8 +/- 4.4 s; mean +/- sem) than oxygen uptake (41.5 +/- 7.2 s) at the onset of exercise. This implies that limb blood flow is in excess of the oxygen requirements of muscle and therefore not the critical determinant for oxygen uptake by muscle. Flow in the lower limb arteries was measured before and after superficial femoral artery angioplasty in 22 patients. In addition, collateral blood flow was estimated using a mathematical model. Follow-up was carried out to 1 year. At 1 month, a significant decrease in profunda femoris artery flow (from 224 +/- 84 to 98 +/- 43 ml min-1, P < 0.05, paired t test) and a marked diminution in collateral flow (from 186 +/- 34 to 18 +/- 8 ml min-1, P < 0.05) was noted with no change in total limb blood flow. As expected, a significant increase in superficial femoral artery blood flow was seen (148 +/- 79 to 312 +/- 94 ml min-1, P < 0.05). From the studies, it can be seen that non-invasive duplex ultrasound flow measurements can reliably be obtained in the lower limb, allowing the kinetics of flow after exercise and the changes in flow after surgical intervention to be evaluated. This work provides a foundation for the study of oxygen kinetics and limb blood flow in athletes, the elderly and patients with peripheral vascular disease.

Collateral Circulation↗
PubMed1996

Blood flow in the lower limb after balloon angioplasty of the superficial femoral artery.

Using duplex ultrasonography lower-limb blood flow measurements were obtained in 20 patients with intermittent claudication. Assessments of flow were made in the common femoral artery, profunda femoris artery (PFA) and superficial femoral artery (SFA) before and after angioplasty for stenoses of short segments of the SFA. Blood flow was measured at rest and after exercise on a cycle ergometer. Collateral flow was calculated using an established mathematical model. Results were compared with the ankle:brachial systolic pressure index (ABPI) after exercise. Although there was no overall increase in resting limb blood flow, an increase in mean(s.d.) SFA flow from 148(79) to 312(94) ml min-1, with a concomitant decrease in PFA flow from 224(84) to 98(43) ml min-1 was noted 1 week after angioplasty (P < 0.05). At rest there was an increase in mean(s.d.) ABPI from 0.62(0.12) to 0.89(0.23) (P < 0.05). Collateral flow was estimated to have decreased from 186(34) to 18(8) ml min-1; the pattern of change in flow was similar after exercise. Angioplasty of the SFA remains controversial because of the risk of restenosis. The above methodology allows assessment of whether patients can re-establish collateral flow or whether limb blood flow will be significantly compromised if restenosis occurs.

Aged↗
PubMed1996

Observer variability in volumetric blood flow measurements in leg arteries using duplex ultrasound.

Duplex ultrasound volumetric flow measurements have not found a major clinical use because of variability caused by errors in estimating cross-sectional area (CSA) and in measuring time averaged mean velocity (TAMeV). We determined inter- and intraobserver variation in volumetric blood flow measured at rest in the common femoral artery (CFA) and its main branches, the superficial femoral (SFA) and profunda femoris (PFA) arteries, in 20 normal subjects. The product of TAMeV and CSA was taken as volumetric flow. The coefficient of variation of TAMeV was consistently greater than that of CSA. Interobserver variation for blood flow (16.2%, 20.2% and 40.3% for CFA, SFA and PFA, respectively) was larger than intraobserver variation (13.0%, 15.1%, 21.2%). In conclusion, these data define the minimum changes in VQ that can be realistically detected and indicate that, with modern duplex Doppler equipment, volumetric flow can be used as a reliable haemodynamic measure for monitoring patients before and after surgical or radiological intervention.

Adult↗
PubMed1996

Haemodynamic and metabolic responses of the lower limb after high intensity exercise in humans.

This study assessed blood flow in the common femoral, superficial femoral and profunda femoris arteries, the effects of vasodilator metabolites and changes in blood pressure and pulse during recovery after high intensity exercise (Wingate test). Mean common femoral artery flow increased sevenfold in response to the exercise. The subsequent decline in mean common femoral artery flow was mono-exponential with a mean time constant of 19 min. The post-exercise increase in profunda femoris artery flow (ninefold) was significantly greater than the superficial femoral artery flow (fourfold, P < 0.05). Systolic blood pressure and heart rate decreased monotonically throughout recovery. In contrast, diastolic blood pressure showed a significant fall below baseline at 3 min (P < 0.05) with a return to baseline at 60 min. The greatest drop below baseline (approximately 20 mmHg) occurred around 7 min. Lactate reached a maximum of 13.6 +/- 2.3 mmol -1 at 8 min (P < 0.05) and was still significantly above baseline at 60 min. pH remained below 7.2 until 20 min of recovery. The results demonstrate that following high intensity exercise, blood flow to the limbs appears to be controlled by complex interactions of various vaso-active metabolites, each contributing proportionally more at different times during recovery.

Adult↗
PubMed1996

Cytochemical localization of Na(+)-K(+)-adenosine triphosphate activity in the proximal convoluted tubule cells of the gerbil Meriones crassus.

The present work describes the cytochemical localization of Na(+)-K(+)-ATPase in the proximal convoluted tubule cells of the gerbil Meriones crassus. By using CeCl3 as capture agent, a fine, uniform reaction product was distributed mainly across the basolateral membranes and at the apical surface. This study provides evidence that the ATPase enzyme studied is actually Na(+)-K(+)-ATPase because acetate buffer (bleaching agent) had no decalcifying effect, nor did the subsequent application of levamisole, an inhibitor of alkaline phosphatase, which can hydrolize ATP. Such findings may serve to provide insights into the regulatory role of the Na(+)-K(+)-ATPase in intra-extra cellular balance in the basolateral membranes of the proximal convoluted tubule cells of this desert animal which show thick basal laminae with their membrane-bound bodies. However, there is a lack of knowledge regarding the transport function of the assayed enzyme and these bodies.

Animals↗