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Biomedical subjects

M H Harrison

Publications and source records attributed to M H Harrison.

At least 19 recordsLinked to original sources
PubMed2006

Human bite injury in North East England--the impact of alcohol intake on a mode of violent assault.

Ninety-two retrospective cases of human bite injury referred to a Plastic Surgery department are presented. Particular emphasis is placed on the relationship of alcohol intake to these injuries, their distribution and subsequent management. A review of the literature is conducted. The human bite is a leisure time injury of the young single male in the North East. It has been shown that there is a clear link to alcohol and in particular weekend drinking. Prompt operative intervention and wounds located at the head and neck have been shown to be associated with a decreased risk of subsequent infection, which reflects findings in the earlier literature. Fifteen cases were infected. One was the result of a postoperative complication. The remainder were infected on admission. The majority of infected cases were upper limb bites and were associated with a delayed presentation.

Adult↗
PubMed1995

Analysis of calcium-lipid complexes in faeces.

Calcium is purported to prevent colorectal cancer by forming insoluble complexes with bile acids and long-chain fatty acids in the large bowel. Therefore, a method for analysing calcium-lipid complexes in faeces has been developed to investigate this. The calcium soaps of a long-chain fatty acid (calcium palmitate) and bile acids (calcium deoxycholate, chenodeoxycholate, cholate and lithocholate) were obtained by organic synthesis. Studies with the authentic soaps reveal that they exist in an empirical ratio of calcium-to-lipid of 1:2. On addition to lipid-free faeces, approximately 30% of calcium palmitate could be recovered and quantified in the authentic state by extraction with 72% ethanol and overnight precipitation at 0 degree C. In contrast, the calcium soaps of the bile acids could not be recovered in the authentic state but were quantified entirely as the free acids. The method was applied to the analyses of calcium-lipid complexes in the faeces of adenoma patients partaking in a placebo-controlled calcium-intervention study. The results show that human faeces contain appreciable amounts of calcium long-chain fatty acid soaps predominantly in the form of calcium palmitate and stearate. The faecal concentration of long-chain fatty acid soaps was increased significantly (P = 0.005) during calcium intervention but this did not have a statistically significant effect on the excretion of free long-chain fatty acids (P = 0.4). Calcium long-chain fatty acid soap formation was found by multiple regression to be equally dependent on stool long-chain fatty acid and calcium concentration. Calcium soaps of the bile acids were not detected by this method.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1988

Effect of longitudinal physical training and water immersion on orthostatic tolerance in men.

To test the hypothesis that moderately intense physical training has no effect on orthostasis, orthostatic and fluid-electrolyte-endocrine responses to 60 degrees head-up tilt were compared before and after 6 h of water immersion (34.5 +/- 0.1 degrees C) up to the neck following 6 months of exercise training. During the tilt test the five male subjects (27-42 years) each wore a lower-body positive-pressure suit (MAST-111A antishock trousers). The tilt procedure consisted of a 40-min supine control period (suit deflated), followed by a maximum 90-min tilt period (suit inflated to 50 +/- 5 mm Hg for 30 min, then deflated for 60 min or until presyncope). The mean +/- S.E. pretraining cycle ergometer peak VO2 was 3.20 +/- 0.14 L.min-1 (39 +/- 2 ml.min-1.kg-1), 3.36 +/- 0.27 L.min-1 (42 +/- 4 ml.min-1.kg-1) after 3 months (N.S.), and increased by 18% to 3.78 +/- 0.36 L.min-1 (48 +/- 5 ml.min-1.kg-1, +22%, p less than 0.05) posttraining. During pretraining, water immersion tilt tolerance decreased from 74 +/- 16 min before to 34 +/- 9 min (delta = 40 min, p less than 0.05) after immersion. During posttraining, water immersion tilt tolerance decreased similarly from 74 +/- 16 min preimmersion to 44 +/- 13 min (delta = 30 min, p less than 0.05) postimmersion (74 vs. 74 min, N.S.; 34 vs. 44 min, N.S.).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Early fluid and protein shifts in men during water immersion.

High precision blood and plasma densitometry was used to measure transvascular fluid shifts during water immersion to the neck. Six men (28-49 years) undertook 30 min of standing immersion in water at 35.0 +/- 0.2 degrees C; immersion was preceded by 30 min control standing in air at 28 +/- 1 degrees C. Blood was sampled from an antecubital catheter for determination of blood density (BD), plasma density (PD), haematocrit (Ht), total plasma protein concentration (PPC), and plasma albumin concentration (PAC). Compared to control, significant decreases (p less than 0.01) in all these measures were observed after 20 min immersion. At 30 min, plasma volume had increased by 11.0 +/- 2.8%; the average density of the fluid shifted from extravascular fluid into the vascular compartment was 1006.3 g.l-1; albumin moved with the fluid and its albumin concentration was about one-third of the plasma protein concentration during early immersion. These calculations are based on the assumption that the F-cell ratio remained unchanged. No changes in erythrocyte water content during immersion were found. Thus, immersion-induced haemodilution is probably accompanied by protein (mainly albumin) augmentation which accompanies the intravascular fluid shift.

Adult↗
PubMed1987

Delayed skeletal maturation in Perthes' disease.

We have studied skeletal maturation and carpal bone development in 27 girls with Perthes' disease by assessing consecutive radiographs during an observation time of 5 years. At the time of diagnosis of Perthes' disease, delayed skeletal maturation was both frequent and considerable and greater than at the end of observation. The mean age at appearance of carpal bones was delayed compared with controls. In bilateral disease, compared with unilateral disease, the onset of ossification in the carpals occurred later.

Age Determination by Skeleton↗
PubMed1987

Plasma volume and endocrine responses to water immersion with intermittent positive-pressure breathing in men.

The effect of intermittent positive-pressure breathing (PB), induced by expiring against a resistance of 12.5 mm Hg, on plasma volume and endocrine responses to standing water immersion, was studied in seven male subjects, 28-49 years of age. The men were immersed to the neck (35 +/- 0.5 degrees C) for 90 min with PB from 30 to 60 min. Compared to control values, the hematocrit and hemoglobin concentration decreased (p less than 0.001) during immersion while plasma osmolality was unchanged, indicating an isotonic increase in plasma volume (hemodilution) which peaked after 75 min at +15.5% of the preimmersion plasma volume. This hemodilution was not significantly affected by PB. Plasma renin activity and vasopressin and aldosterone concentrations decreased progressively throughout immersion (p less than 0.001) and were unaffected by PB. The magnitude of these hormonal decreases was accentuated by preexisting, presyncopal symptoms in four subjects. It is concluded that intermittent PB as 12.5 mm Hg failed to compensate for the negative-pressure breathing of standing subjects immersed in water to the neck.

Adult↗
PubMed1986

Effect of posture on arterial baroreflex control of heart rate in humans.

Altered baroreflex function may contribute to the cardiovascular changes associated with weightlessness. Since central blood volume (CBV) increases during simulated weightlessness we have examined the possibility that acute changes in CBV may modify baroreceptor function. We used graded head-up tilt (HUT) and head-down tilt (HDT) to induce changes in CBV, and neck suction to stimulate carotid baroreceptors, in 6 subjects. The increase in pulse interval induced by a negative pressure of 8.2 kPa (62 mm Hg) imposed for 10 s while supine was compared with the increase while tilted for 8 min at +/- 15 degrees, +/- 30 degrees and +/- 45 degrees. During HDT at 15 degrees the pulse interval over the first 5 cardiac cycles following suction onset was 51 +/- (SEM) 18 ms longer (p less than 0.05), at 30 degrees it was 61 +/- 20 ms longer (p less than 0.05), and at 45 degrees it was 74 +/- 35 ms longer (p less than 0.01), compared with supine. During HUT at 15 degrees the pulse interval was 25 +/- 9 ms shorter (p less than 0.05) than when supine, but was not significantly different at 30 degrees and 45 degrees. These responses occurred independently of changes in brachial blood pressure. Attenuation was also observed after 5 min (56 +/- 17 ms; less than 0.05), and after 40 min (25 +/- 9 ms; p less than 0.05) of 60 degrees HUT compared with supine. We conclude that posture does modify arterial baroreflex control of heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Effect of hydration on some orthostatic and haematological responses to head-up tilt.

Experiments were undertaken to determine the effects of hydration status on a) orthostatic responses, and on b), relative changes in intravascular volume and protein content, during 70 degrees head-up tilt (HUT). Six men underwent 45 min of HUT, preceded by 45 min supine, first dehydrated, and again 105 min later after rehydration with water. Heart rate was consistently lower following rehydration (p less than 0.01), while supine diastolic pressure was higher (p less than 0.02). Systolic pressure fell during dehydrated HUT (p less than 0.01), but not during rehydrated HUT. Postural haemoconcentration, which was reduced after rehydration (p less than 0.001), was accompanied by a decrease in intravascular albumin content (p less than 0.05). Two subjects experienced severe presyncopal symptoms during dehydrated HUT, but not during rehydrated HUT. Thus, it appears that rehydration after fluid restriction improves orthostatic tolerance. Furthermore, extravascular hydration status may be more important than intravascular hydration status in determining orthostatic tolerance.

Adult↗
PubMed1986

Effect of hydration on plasma volume and endocrine responses to water immersion.

To determine the effect of hydration on the early osmotic and intravascular volume and endocrine responses to water immersion the hematocrit, hemoglobin, plasma renin activity (PRA), and plasma electrolyte, aldosterone (PA), and vasopressin (PVP) concentrations were measured during immersion following 24-h dehydration; these were compared with corresponding values following rapid rehydration. Six men and one woman (age 23-46 yr) underwent 45 min of standing immersion to the neck preceded by 45-min standing without immersion, first dehydrated, and then 105 min later after rehydration with water. Immersion caused an isotonic expansion of the plasma volume (P less than 0.001), which occurred independently of hydration status. Suppression of PRA (P less than 0.001) and PA (P less than 0.001) during both immersions also occurred independently of hydration status. Suppression of plasma vasopressin was observed during dehydrated immersion (P less than 0.001) but not during rehydrated immersion. It is concluded that plasma tonicity is not a factor influencing PVP suppression during water immersion.

Adult↗
PubMed1986

Effect of hydration on plasma vasopressin, renin, and aldosterone responses to head-up tilt.

If plasma vasopressin (PVP), plasma renin (PRA), and plasma aldosterone (PA) responses to change in posture are mediated only by alterations in intrathoracic baroreceptor activity, hydration status should have minimal influence on these responses. To test this hypothesis, six male subjects underwent 45 min of 70 degree head-up tilt (HUT) following 26 h dehydration, and again, 105 min later, following rehydration. Compared with preceding supine hydrated control values, PVP, PRA, and PA increased (p less than 0.001) during dehydrated HUT, but only PVP and PRA increased during rehydrated HUT (p less than 0.001). The dissociation during rehydrated HUT of PRA and PA may have been related more to the reduction (p less than 0.001) in plasma potassium concentration than to the accompanying decrease (p less than 0.001) in plasma osmolality and sodium concentration. Although increases in PVP and PRA during HUT were attenuated (p less than 0.01) following rehydration, this attenuation was associated with the absence of symptoms of overt hypotension following rehydration. However, since rehydration did not abolish the increases in PVP and PRA induced by HUT, it is concluded that the present observations support the concept of intrathoracic baroreceptor involvement in the regulation of vasopressin secretion and renin release.

Adult↗
PubMed1986

Femoral head shape in Perthes' disease. Is the contralateral hip abnormal?

Femoral head shape has been assessed in 47 children with unilateral Perthes' disease and 41 control children. Measurements were taken from radiographs and arthrographs by a computerized method. In controls the femoral head was round, particularly in lateral outline, and characteristically asymmetric in anteroposterior views at all ages studied. In children with Perthes' disease the bony femoral head was less round than in controls and flattened anteriorly. Mediolateral symmetry differed from that of controls, reflecting lateral flattening of the cross section of the femoral epiphysis. Age-related changes correlated with disease duration but not with treatment. The "unaffected" hip showed some evidence of anterior and lateral flattening from the time of diagnosis of disease in the other hip. No subject developed bilateral disease during the follow-up period. This early involvement of the "unaffected" hip could indicate a constitutional abnormality. The cartilaginous femoral head was rounder than the underlying bony epiphysis, particularly in anteroposterior views. The cartilage of the hip with Perthes' disease was less round than that on the "unaffected" side. There was no evidence of anterior or lateral flattening of either cartilaginous femoral head.

Adolescent↗
PubMed1985

Effects on thermal stress and exercise on blood volume in humans.

The opening remarks of this review emphasize, somewhat pessimistically, the serious disagreements, going back over a hundred years, between different investigators regarding effects of exercise and thermal stress on intravascular volume. However, the concluding remarks may legitimately assume a more optimistic, positive aspect, and a certain degree of order and sense may be brought to what had superficially appeared to be the chaos and confusion of conflicting observations and conclusions. Krebs and Meyer's (162) "marked differences in findings between one investigator and another," and Senay's (245) comment 77 years later that "disagreements abound" can now be seen as an inevitable consequence of the widely differing experimental protocols and procedures that have been adopted. Of particular importance in this respect is the failure to standardize conditions before subjects are exposed to thermal stress or begin to exercise--notably in terms of posture and environmental temperature; both may profoundly influence blood volume responses, quantitatively and qualitatively. Then there is subject status; physical fitness, heat acclimatization, and dehydration are important factors contributing to the variability of individual responses to thermal stress and exercise. With the causes of disagreement at least identified, it is now possible to answer the question posed in section I: Is thermal- and exercise-induced hemoconcentration fact or fantasy? Undeniably it is fact, but only under certain circumstances. For example, in resting subjects reduction in blood volume is associated only with high environmental temperatures above the upper limit of the prescriptive zone; within the upper part of the zone, blood volume commonly increases. If heat exposure is preceded by a control period in a cool environment, transient hemodilution is generally observed, followed by hemoconcentration after entry into the heat as skin temperature rises, cutaneous blood flow increases, and sweating begins. Exercise too causes hemoconcentration, but only if the exercise is performed in a supine or seated, not in an upright (standing), position. Hence cycling is almost always associated with a reduction in plasma volume, as is arm exercise and swimming. Bench stepping, walking, and running, on the other hand, are associated with an extremely variable intravascular volume response. If allowance is made for the reduction in plasma volume that occurs when moving to an upright position from a supine or seated position, the initial rapid hemoconcentration seen at the onset of cycling exercise is absent with bench stepping, walking, and running.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1985

Blood pressure and plasma renin activity as predictors of orthostatic intolerance.

Some physiological responses to head-up tilt and 3 h standing were evaluated in 13 dehydrated subjects. Seven of the subjects proved to be orthostatically intolerant (INT), exhibiting presyncopal symptoms. Before the symptoms manifest themselves the INT subjects had consistently lower (p less than 0.05) systolic blood pressures, generally lower diastolic and pulse pressures, and elevated (p less than 0.05) plasma renin activity (PRA) compared to the tolerant (TOL) subjects. Plasma vasopressin usually increased more in the INT subjects, but appeared to be related to the severity of presyncopal symptoms rather than to the upright posture per se. It is concluded that systolic and pulse pressures, with PRA, may allow discrimination between TOL, and potentially INT individuals; i.e., predict orthostatic intolerance. It is suggested that dehydration could provide a valuable physiological model for elucidating the causes of orthostatic intolerance.

Adult↗
PubMed1984

Coxa plana--the fate of the physis.

Eighty patients who had unilateral coxa plana and who had been treated conservatively were followed to a mean age of sixteen and one-quarter years, and their cases were reviewed for radiographic evidence of a disturbance of the femoral capital growth plate. This physeal involvement was inferred by the presence of one or more of five findings: premature physeal closure, overgrowth of the greater trochanter, change in physeal shape, lateral protrusion of the capital nucleus, and medial bowing of the femoral neck. Premature physeal closure, which was more common in the girls than in the boys, occurred in 25 per cent of the affected femoral heads, and 90 per cent of the patients showed some interference with normal physeal growth in the affected femoral head. A direct correlation was found between the severity of the physeal involvement and the ultimate deformity of the femoral head. The possible causes of interference with physeal growth and damage are discussed.

Bone Diseases, Developmental↗
PubMed1984

Use of pulsed electromagnetic fields in Perthes disease: report of a pilot study.

A pilot study of pulsed electromagnetic fields (PEMFs) in the treatment of 10 older children with unilateral Perthes disease of the hip is reported. Patients were allowed to walk using crutches, with the affected hip splinted by the Birmingham containment orthosis during the day. For 10 h during the night the affected hip was exposed to PEMFs delivered via a pair of coils, mounted anterior and posterior to the hip joint on a plastic abduction orthosis. Splintage time of this group was compared with that of 72 patients selected at random from a historical control group of 200 patients. The 72 patients and the 10 children were assigned to early or late groups depending on the radiologic evolution of the disease when treatment commenced. The group of 10 children showed an overall reduction of time in all splintage of 32% in early cases (to 12.8 months) and 18% in late cases (to 13.5 months). No untoward effects were detected during the 2 years that these children have been under observation. In view of the apparent safety of PEMFs and their effects in this limited population of older patients with advanced Perthes disease, a double-blind study in younger patients with earlier lesions seems to be justified.

Child↗