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Biomedical subjects

S K Shami

Publications and source records attributed to S K Shami.

At least 19 recordsLinked to original sources
PubMed1994

Microangiopathy of the skin and the effect of leg compression in patients with chronic venous insufficiency.

PURPOSE: The reasons for the efficacy of leg compression in the treatment of chronic venous insufficiency are not clear. We have used laser Doppler fluxmetry to assess the effect of external compression on the skin microcirculation. METHODS: Fifteen patients with lipodermatosclerosis caused by chronic venous insufficiency and 15 control subjects were studied in the supine and sitting positions. The laser Doppler probe, incorporated in a polyethylene chamber, was applied to the lower leg underneath a blood pressure cuff. Pressures were applied from 10 to 100 mm Hg in increments of 10 mm Hg. A computer data logging system recorded laser Doppler flux blood cell velocity, and concentration of moving blood cells. RESULTS: In patients in the supine position, 20 mm Hg compression resulted in a median increase of 33% in laser Doppler flux, and a median increase of 79% in blood cell velocity, but higher pressures caused a progressive decrease in laser Doppler flux and blood cell velocity. With the patient in the sitting position, compression up to 60 mm Hg caused an increase in laser Doppler flux (median percentage increase at 20 mm Hg compression 84%) and blood cell velocity (median percentage increase at 20 mm Hg compression 22%). At 20 mm Hg compression, the concentration of moving blood cells decreased in the supine position (median percentage fall 27%) but did not change significantly in the dependent position. The effects of compression in control subjects were similar to those in patients, but to a lesser degree. CONCLUSION: Our study suggests that compression treatment may achieve part of its effect by causing an increase in the microcirculatory flow velocity.

Aged↗
PubMed1993

Hyperaemic response in the skin microcirculation of patients with chronic venous insufficiency.

The capacity of the microcirculation in the liposclerotic skin of patients with chronic venous insufficiency to vasodilate in response to pilocarpine electrophoresis was assessed using laser Doppler fluxmetry. Pilocarpine induces vasodilation by direct action on capillaries; other methods of vasodilatation, such as heating of the skin, act by a number of pathways including a neurogenic one. Thirty patients with lipodermatosclerosis and chronic venous insufficiency and 20 control subjects were studied. There was no difference in peak vasodilatation following pilocarpine electrophoresis in the two groups. The median (interquartile range) peak flux in patients was 665 (382-1025) units and in controls 765 (452-975) units (95 per cent confidence interval of difference--270 to 150 units, P = 0.5). This suggests that the capillaries in the liposclerotic skin of patients with chronic venous insufficiency have a normal capacity to vasodilate.

Aged↗
PubMed1993

When do vascular surgeons prescribe antiplatelet therapy? Current attitudes.

A large number of studies have addressed the efficacy of antiplatelet agents in the prevention of primary and secondary atherosclerotic events. We have undertaken to review the literature and conclude that there is good evidence for the routine prescription of antiplatelet therapy in the prevention of secondary atherosclerotic events in patients with unstable angina, myocardial infarction, transient ischaemic attacks and post-arterial reconstruction. The evidence for any benefit in the prevention of vascular graft occlusion is less clear cut. We therefore conducted a postal survey of Vascular Surgeons in Britain and Ireland, receiving 112 responses to 134 questionnaires. Forty-seven percent of surgeons used antiplatelet therapy following any vascular procedure that they undertook. The rest were more selective in their use of these drugs, reserving them for specific vascular reconstruction, e.g. with synthetic grafts. Five percent of surgeons used anti-platelet aggregating prophylaxis only in patients following transluminal balloon angioplasty. In view of extensive evidence of reduction in long-term vascular mortality and non-fatal vascular events by the use of these drugs in patients who have had a primary vascular event, we would suggest that there is a strong argument for the routine use of anti-platelet drugs in patients presenting with arterial disease to a Vascular Surgeon, regardless of vascular reconstruction, angioplasty or type of graft used.

Angioplasty, Balloon↗
PubMed1993

Peripheral nerve function in chronic venous insufficiency.

Abnormalities of vasomotion, impairment of the venoarteriolar reflex and increased skin blood flow reported in the liposclerotic skin of patients with chronic venous insufficiency (CVI) suggest altered nervous control of the skin microcirculation. The aim of this study was to determine whether patients with CVI have a peripheral neuropathy. Forty patients with CVI and lipodermatosclerosis (LDS) and 35 age and sex-matched controls were examined for neuropathy using three modalities of testing. Threshold to warming was used to assess unmyelinated fibres, and threshold to cooling and vibration to assess myelinated fibres. Warming and cooling thresholds were measured on the sole of the foot by a purpose built, computer controlled instrument. The threshold to vibration was measured on the big toe using the Ohio Bio-thesiometer. A significantly raised threshold to warming and vibration was found in the CVI group compared to the normal controls [median threshold to warming (interquartile range) in CVI group = 5.3 (0.1-9.1) median threshold to warming (interquartile range) in controls = 1.21 (0.17-3.5), p = 0.005 and median threshold to vibration (interquartile range) in CVI group = 22 (13-31) median threshold to vibration (interquartile range) in controls = 12 (8.5-27.5), p = 0.024]. The thresholds to cooling was not statistically different in the two groups. This study demonstrates the presence of a peripheral neuropathy in patients with chronic venous insufficiency, and this may be important in the pathogenesis of venous ulceration.

Aged↗
PubMed1993

Microvascular investigations in diabetes mellitus.

This paper reviews the current literature concerning the different investigative modalities available to assess the microcirculation in diabetic microangiopathy. The advantages and disadvantages of the different invasive and noninvasive methods available are presented objectively. We have concentrated on the tests that provide a quantitative assessment of the microcirculation, including laser Doppler fluxmetry, capillary microscopy, plethysmography, transcutaneous oximetry and radioactive isotope clearance. Some of the invasive methods described are now being replaced by noninvasive equivalents, providing similar information with less discomfort and risk to the patient.

Diabetic Angiopathies↗
PubMed1993

The veno-arteriolar reflex in chronic venous insufficiency.

The aim of this study was to evaluate the veno-arteriolar reflex in the gaiter area and in the big toe of patients with chronic venous insufficiency (CVI). Twenty patients with lipodermatosclerosis and CVI comprised the disease group, and twenty subjects without venous disease comprised the control group. The activity of the veno-arteriolar reflex in the gaiter area and in the big toe in the affected and unaffected limbs of patients with CVI, and in normal controls was assessed by calculating the percentage fall in skin blood flux on dependency as measured by Laser Doppler fluxmetry. The results showed that the veno-arteriolar reflex was normal in the gaiter area in both the affected limb and the unaffected limb in patients with CVI compared to normal controls, [median percentage fall in flux and interquartile range for affected limb in patients with CVI = 49 (35-69), for the unaffected limb of patients with CVI = 41 (24-58), for normal controls = 49 (31-57), p value (Mann-Whitney) for patient groups compared to normals = 0.52, 0.60 respectively]. However in the big toe the veno-arteriolar reflex was impaired in the affected limb of patients with CVI compared to both the unaffected limb and to normal controls, [median percentage fall in flux and interquartile range for affected limb in patients with CVI = 52 (29-64), for the unaffected limb of patients with CVI = 69 (45-78), for normal controls = 75 (51-80), p value (Mann-Whitney) for patient groups compared to normals = 0.017, 0.92 respectively].(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Venous ulcers and the superficial venous system.

PURPOSE: The purpose of this study is to identify the anatomic location of venous disease in patients with venous ulceration and chronic venous insufficiency. METHODS: Both limbs of 59 consecutive patients attending the Middlesex Hospital Vascular Laboratory (London, U.K.) with venous ulceration were assessed by color duplex ultrasound scanning to determine the location of venous disease. RESULTS: Isolated deep venous reflux was present in only 12 limbs (15%). A combination of deep and superficial venous reflux was found in 25 limbs (32%), and in 42 limbs (53%) there was only superficial venous reflux. CONCLUSION: In just over half the patients with venous ulceration, the disease is confined to the superficial venous system. This group of patients may benefit from surgical treatment. This study emphasizes the need for vascular laboratory investigation of patients with leg ulceration.

Aged↗
PubMed1992

Functional assessment of the sympathetic innervation of the microcirculation of the lower urinary tract: a preliminary report.

This paper presents preliminary data on a new method for testing the sympathetic innervation of the urothelium. A flexible laser Doppler probe was introduced into the urethra of two females and two male subjects. The percentage fall in laser Doppler flux following generalized sympathetic stimulation by taking an inspiratory gasp was measured. This resulted in 36%, 32%, 68% and 34% mean drop in urothelial blood flux. In the female subjects, the probe was advanced into the bladder and the procedure repeated, and the gasp resulted in 60% and 83% drop in flux. With laser Doppler fluxmetry, fall in microcirculatory blood flow associated with a generalized increase in sympathetic tone, therefore can be demonstrated. This method may be useful in the assessment of the integrity of the sympathetic innervation of the urothelium in patients with suspected autonomic dysfunction of the genitourinary tract.

Adult↗
PubMed1992

Leg ulcers.

Explore the source record for details and available documents.

Humans↗
PubMed1992

Leg ulceration in venous disease.

We have given a brief summary of the scale of the problem caused by venous ulceration in the UK, and have then reviewed the various theories of causation, including a historical survey, and presented the evidence for and against the two main current theories of fibrin cuffs and white cell trapping. We also outline previous hypotheses of the aetiology of venous ulceration, including arteriovenous microanastomoses, stasis and oedema. The contribution of superficial venous incompetence in the pathogenesis of ulceration is also examined.

Arteriovenous Fistula↗
PubMed1992

Vasomotion in the leg skin of patients with chronic venous insufficiency.

The characteristics of vasomotor activity in patients with lipodermatosclerosis (LDS) were studied using Laser Doppler fluxmetry and frequency analysis. Laser Doppler flux in the skin was recorded in the goiter region in 17 patients with LDS due to venous disease and in 16 normal control subjects. The Laser Doppler signals were analysed to give mean levels of flux and the frequency and amplitude of vasomotion were found using a fast Fourier transform (FFT). The results show significantly greater basal flow (p less than .001), and vasomotor frequency (p less than .001) and amplitude (p less than .001) in venous disease. The altered vasomotor activity is not due simply to the increased flow in LDS since increasing the flow in normal skin using the vasodilator pilocarpine does not produce as noticeable a difference.

Adult↗
PubMed1991

Vasodilatory capacity of the skin in venous disease and its relationship to transcutaneous oxygen tension.

Low transcutaneous oxygen tension (Ptc,O2) values in the supramalleolar skin of patients with venous disease are often reported. This measurement involves heating the skin to 43 degrees C to cause maximum vasodilatation and is valid only if liposclerotic and normal skin can vasodilate to the same degree. Forty-four limbs were studied, 15 with lipodermatosclerosis (LDS), 14 with uncomplicated varicose veins, and 15 controls. A Ptc,O2 electrode was modified to incorporate a laser Doppler probe. Laser Doppler flux was measured in the supramalleolar skin before and after local heating to 43 degrees C and the relative increase in flux was measured. The Ptc,O2 was then measured at the same site and on the chest. Vasodilatory capacity was expressed as the ratio of peak:basal laser Doppler flow, and the Ptc,O2 was expressed as a leg:chest ratio. Median laser Doppler flow was higher in limbs with LDS (median 67 mV) than in normal limbs (median 40 mV) (P less than 0.03). Ptc,O2 was higher in control limbs (median ratio 0.94) than in limbs with LDS (median 0.53) (P less than 0.006). The microcirculation in LDS had less capacity to vasodilate after heating (median factor of increase 5.4) than normal skin (median factor of increase 12.3) (P less than 0.001). A simple regression analysis was performed on all pairs of data, and revealed a correlation between Ptc,O2 and vasodilatory capacity (r = 0.524, P less than 0.001). The results indicate that low Ptc,O2 levels in venous disease reflect an inability of the microcirculation to increase its flow in response to local heating; inferences about the oxygen content of liposclerotic skin at normal temperatures cannot be drawn using this technique.

Adult↗
PubMed1991

Helicobacter pylori: a Jordanian study.

The prevalence of Helicobacter pylori in patients with upper gastrointestinal symptoms in the north of Jordan was studied prospectively. The occurrence of H. pylori was documented histologically and bacteriologically in 169 patients attending endoscopy for upper gastrointestinal symptoms. Our results showed that H. pylori was present in 70% of patients with acute gastritis, 73% of patients with chronic gastritis, 68% of patients with acute on chronic gastritis, 83% of patients with duodenal ulceration, 75% of the patients with gastric ulceration, 64% of patients with no pathology, and 68% of patients regardless of the pathology found. There was a sharp rise in the prevalence of H. pylori with age, up to the age of 40 years with an annual increase in the prevalence of 2%. This study shows that the prevalence of H. pylori in Jordan is similar to that seen in other developing countries with infections occurring at a lower age and with the annual infection rate being double that seen in developed countries.

Adolescent↗
PubMed1991

Vasomotion in venous disease.

Abnormalities of the capillary microcirculation may be important in the pathogenesis of venous ulceration. In this study the characteristics of capillary vasomotion in venous disease have been studied using laser Doppler flowmetry. The amplitude and frequency of vasomotion in the skin microcirculation as measured by laser Doppler flowmetry was determined in 101 subjects. These comprised 43 subjects with venous disease and lipodermatosclerosis (LDS), 14 subjects with uncomplicated varicose veins (VV), and 44 normal controls. In 43 of these 101 limbs, vasomotion was also measured after heating the skin to 43 degrees C. The resting laser Doppler flux was significantly higher in the LDS group compared to the other two groups (LDS median = 76, VV median = 47 (P less than 0.04), controls median = 49 (P less than 0.003]. The amplitude of vasomotive waves was significantly higher in the LDS group compared to controls (LDS median = 20, VV median = 8.3 (P less than 0.007), controls median = 14 (P less than 0.007), as was the frequency of vasomotion (LDS median = 3.3 waves/min, VV median = 2.5 (P = ns), controls median = 2.7 (P less than 0.007]. On heating the skin to 43 degrees C the frequency of the vasomotion increased significantly in the control (P less than 0.004) and VV (P less than 0.04) groups but not in the LDS group. The amplitude of the vaso-motion also increased significantly in the control (P less than 0.01) and VV (P less than 0.002) groups but not in the LDS group.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1991

Microangiopathy in diabetes mellitus: II. Features, complications and investigation.

This paper reviews the current literature on the morphological, physiological, pathological and rheological features of microangiopathy in diabetes mellitus. The current theories explaining the development of these features as well as complications resulting from them are discussed. In the first section the morphological changes including capillary basement membrane thickening as well as physiological changes such as increased permeability and reduced diffusion of oxygen across capillary endothelium are discussed. Rheological factors and functional changes in blood flow as well as capillary proliferation and degeneration are addressed. The second section of this paper deals with the complications suffered by diabetics such as retinopathy, nephropathy, neuropathy, cardiovascular disease and skin ulceration. The role of microangiopathy in the pathogenesis of these complications is reviewed. The last section discusses the investigative techniques available to the clinician and researcher in the study of micro-angiopathy. These include various methods of blood flow measurement such as plethysmography, LASER Doppler flowmetry, capillary microscopy and clearance of tracers from the skin microcirculation.

Basement Membrane↗
PubMed1991

Microangiopathy in diabetes mellitus: I. Causes, prevention and treatment.

Microangiopathy is the major cause of death in Insulin Dependent Diabetes Mellitus. However, the pathogenesis of microangiopathy is still far from clear. This paper is a review of the literature on diabetic microangiopathy and discusses the current theories concerning its causes, prevention and treatment. The roles of abnormal glucose metabolism, protein glycosylation, genetic factors and puberty as well as the changes in vascular endothelium, capillary permeability and blood constituents, in the development of microangiopathy are discussed. The benefits of strict control of blood glucose concentrations are discussed along with the action of various pharmaceutical preparations such as aldose reductase inhibitors, hydroxyrutosides, pentoxifylline and free radical scavengers currently assessed in the prevention or treatment of diabetic microangiopathy.

Adolescent↗