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Biomedical subjects

S Greaves

Publications and source records attributed to S Greaves.

28 records · Page 2Linked to original sources
PubMed1998

Assessment of regional left ventricular wall stress after myocardial infarction by echocardiography-based structural analysis.

OBJECTIVES: The objective of this study was to determine the distribution of regional left ventricular (LV) wall stress after myocardial infarction (MI). BACKGROUND: After a large MI, structural changes occur in the heart that ultimately may lead to alterations in LV size and shape, a process generally referred to as ventricular remodeling. Regional variation in myocardial wall stress may be responsible for initiation of physiologic and cellular changes that result in myocardial hypertrophy, dilatation, and remodeling after MI. Simplified geometric analytic methods of estimating global LV wall stress cannot determine regional variation such as that occurring after MI. METHODS AND RESULTS: To assess regional LV wall stress after MI, we applied the finite element method to patient-specific end-systolic LV models generated from echocardiographic imaging. After validation by comparison with analytic solutions of LV wall stress in idealized ventricles, LV models were constructed from rotated orthogonal apical images from 13 normal volunteers, 16 patients with recent (<4 days) anterior MI, and 7 patients with recent infero-posterior MI. The mean Von Mises stress was calculated for the entire LV and for 5 separate regions of the LV. Von Mises LV wall stress was increased globally in patients with anterior MI (211 +/- 46 kdyne/cm2; P < .002) or infero-posterior MI (175 +/- 23 kdyne/cm2; P = .04) compared with normal patients (144 +/- 57 kdyne/cm2). Global wall stress correlated directly with ejection fraction (P < .0001) and inversely with wall motion index (P < .004) in patients with anterior MI. Wall stress in the apical regions was increased by a factor of 2.3 in patients with anterior MI (P < .0001), whereas other regions did not differ from normal patients. There were no individual regions that were significantly different from normal in patients with infero-posterior MI. CONCLUSIONS: Anterior MI is associated with an increase in apical end-systolic wall stress compared with normal and infero-posterior MI. This may be an important stimulus for LV remodeling after anterior MI.

Female↗
PubMed1996

Helicobacter pylori gastritis and serum pepsinogen levels in a healthy population: development of a biomarker strategy for gastric atrophy in high risk groups.

This study aimed to estimate the prevalence and type of chronic gastritis in an asymptomatic working population and to determine whether a combination of serum pepsinogen levels and Helicobacter pylori serology could be used to identify a subgroup with atrophic gastritis at elevated risk of gastric carcinoma. A 10% subsample of 544 male volunteer factory workers aged 18-63 years and participating in a larger study underwent endoscopy and biopsy. Of these men, 29 were seropositive for Helicobacter pylori; all but three (89.7%) had chronic gastritis. Serum pepsinogen A levels increased with progression from a corpus predominant pattern of gastritis through pangastritis to an antral predominant pattern. Nine subjects had corpus atrophy, which was in most cases accompanied by fasting hypochlorhydria and hypergastrinaemia. A combination of pepsinogen A below 80 ng ml-1 and Helicobaceter pylori seropositivity detected corpus atrophy with sensitivity 88.9% and specificity 92.3%. A second screening stage, using a pepsinogen A/C ratio of below 2.5 as a cut-off, resulted in a reduction in numbers requiring further investigation but with some loss of sensitivity (77.8%). Application of this two-stage screening programme to the original sample of 544 workers would have resulted in 11 (2.2%) men being selected for follow-up, excluding 25 (5.1%) false negatives. Our results suggest that a combination of serum pepsinogen levels and Helicobacter pylori serology could be useful as a biomarker strategy for detection of individuals at increased risk of gastric carcinoma and for non-invasive investigation of the natural history of Helicobacter pylori gastritis.

Adolescent↗
PubMed1995

Variability in serum pepsinogen levels in an asymptomatic population.

OBJECTIVE: To investigate the variability in serum pepsinogen levels in an asymptomatic population. DESIGN: Cross-sectional survey of 420 men aged 18-63 years, without symptoms or a history of gastric disease, recruited from four factories in Stoke-on-Trent. METHODS: During an interview, data on history of gastric health, 'lifestyle' and occupation were collected, blood samples were taken for measurement of serum pepsinogen and anti-Helicobacter pylori antibody levels and height and weight were measured. RESULTS: Extreme (low/high) levels of pepsinogens A and C, indicative of chronic gastritis, were found in 24 (5.7%) and 61 (14.5%) of the participants, respectively. Low A-C ratios, indicative of moderate or severe gastric atrophy, were found in 13 (3.1%) participants. Of the variables examined, Helicobacter pylori serology had the strongest influence on serum pepsinogen levels. Serum pepsinogen A and C levels were significantly higher in the 33.6% of participants who were seropositive. The effect was more marked for pepsinogen C; thus, A-C ratios were lower in seropositive individuals. In seronegative participants, both pepsinogen A and pepsinogen C levels increased with increasing age; pepsinogen A levels increased with increasing height and were higher in smokers, but decreased with increasing weight. The effect of smoking on pepsinogen A levels was also detectable in seropositive individuals, but was considerably less marked. Among seronegative participants, those employed on the 'shop-floor' in manual jobs had higher serum pepsinogen C levels and lower A-C ratios than office-based workers. CONCLUSION: H. pylori serology was a major source of variation in serum pepsinogen levels, but causes of gastritis other than H. pylori were indicated. Independent of these effects, serum pepsinogen levels may also vary with age, height and weight. Screening of serum pepsinogen levels in the general population may identify 5-15% who require further investigation. Other 'filters' may be required in conjunction with serum pepsinogen levels to identify those needing investigation for significant gastric pathology.

Adult↗
PubMed1994

Relation between infection with Helicobacter pylori and living conditions in childhood: evidence for person to person transmission in early life.

OBJECTIVES: To relate the prevalence of infection with Helicobacter pylori in adults to their living conditions in childhood to identify risk factors for infection. DESIGN: Prevalence study of IgG antibodies to H pylori (> 10 micrograms IgG/ml, determined by enzyme linked immunosorbent assay (ELISA)) and reported living conditions and other socioeconomic factors in childhood. SETTING: Three factories in Stoke on Trent. SUBJECTS: 471 male volunteers aged 18 to 65 years. MAIN OUTCOME MEASURES: Seroprevalence and variables in childhood. RESULTS: Seroprevalence of H pylori increased with age (22/74 (29.7%) at < 30 years v 29/46 (63%) at 55-65 years; P < 0.001 for trend) and was related to manual occupation (14/65 (21.5%) for non-manual v 162/406 (39.9%) for manual; P = 0.003). After data were adjusted for age and occupation subjects from large families, whose childhood homes were crowded or who regularly shared a bed in childhood, were significantly more likely to be seropositive (adjusted odds ratio (95% confidence interval) 2.15 (1.41 to 3.30) for crowding and 2.13 (1.38 to 3.30) for sharing a bed), but there was no relation with possession of a bathroom, inside toilet, refrigerator, or household pets in childhood. CONCLUSIONS: Close person to person contact in childhood is an important determinant of seroprevalence of H pylori in adulthood, suggesting that the infection is transmitted directly from one person to another and may be commonly acquired in early life.

Adolescent↗
PubMed1994

Doppler echocardiography and the early diagnosis of carditis in acute rheumatic fever.

BACKGROUND: The incidence of acute rheumatic fever in New Zealand remains relatively high. Reliable early diagnosis of carditis is difficult and important in management. AIM: To determine if Doppler echocardiography contributed to the early diagnosis of carditis in acute rheumatic fever. METHODS: Forty-seven patients admitted to hospital with suspected acute rheumatic fever and 19 control patients, with a febrile illness due to a documented non-cardiac bacterial infection, were assessed two days and two weeks following admission. Presence or absence of clinical carditis was determined by a cardiologist unaware of the suspected diagnosis, from clinical examination, chest radiograph, electrocardiogram (ECG) and two dimensional echocardiogram. Doppler echocardiography was then performed and interpreted by a second cardiologist unaware of the diagnosis. After completion of the study the Jones criteria were applied, to categorise the patients with suspected acute rheumatic fever into four groups for the final diagnosis: no acute rheumatic fever, possible acute rheumatic fever, definite acute rheumatic fever without carditis, and definite acute rheumatic fever with carditis. RESULTS: In 19 patients with a final diagnosis of acute rheumatic fever and carditis at the baseline assessment carditis was detected by clinical assessment in 15 patients, compared with 19 patients with evidence of significant valve regurgitation by Doppler echocardiography. Following the two week assessment, all 19 patients had both clinical and Doppler evidence of carditis. Five patients with a final clinical diagnosis of possible acute rheumatic fever or definite acute rheumatic fever without carditis, had a Doppler abnormality detected. There was no clinical or Doppler abnormality in the febrile controls. CONCLUSIONS: Doppler echocardiography is more sensitive than clinical assessment in the detection of carditis in acute rheumatic fever, and can contribute to earlier diagnosis.

Acute Disease↗
PubMed1991

Early prevention of left ventricular dysfunction after myocardial infarction with angiotensin-converting-enzyme inhibition.

Left ventricular dysfunction can be improved with angiotensin-converting-enzyme inhibition started 1 week after myocardial infarction or later. To see whether earlier intervention may confer greater benefit, a double-blind study was carried out in which 100 patients with Q wave myocardial infarction, but without clinical heart failure, were randomly allocated treatment with captopril 50 mg twice daily or placebo starting 24-48 h after onset of symptoms. Left ventricular volumes were measured regularly during 3 months of treatment and after a 48 h withdrawal period by means of two-dimensional echocardiography. The placebo group showed significant increases in left ventricular end-diastolic (LVEDVI) and end-systolic (LVESVI) volume indices, with the ejection fraction unchanged. By contrast, the captopril group showed a slight but not significant rise in LVEDVI and a significant reduction in LVESVI with ejection fraction increased significantly. At 3 months there was a 4.6% difference in the change in ejection fraction from baseline between the groups (p less than 0.0001). Most of the treatment benefit was evident at 1 month and there were no changes in left ventricular volumes after 48 h withdrawal of treatment at 3 months. Heart failure requiring treatment with frusemide developed in 7 patients in each group during the study period; 3 of these (1 captopril-treated, 2 placebo-treated) had to be withdrawn from the trial with severe heart failure requiring open treatment. Thus early treatment with captopril is effective in preventing the ventricular dilatation that can occur after Q wave myocardial infarction.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1986

Effects of cold stress and exercise on fat loss in females.

A Latin Square design has been used to test the responses of 24 relatively fit young women to 200 minute bouts of exercise performed over 5 day trials under each of three different ambient conditions: 15 degrees C (warm-warm; (WW)); -20 degrees C while inhaling, from a facemask, air heated to 18 degrees C (cold-warm; (CW)); and -20 degrees C (cold-cold; (CC)). In both of the cold environments, special clothing and boots were provided (insulation 0.47 degree C X watt-1 X m-2 and 0.62 degree C X watt-1 X m-2; (4 and 3 CLO units)). All three trials led to a small (0.6-0.7 degree C) rise of rectal temperature, but in the two cold environments mean body temperatures fell by over 1.0 degree C. A large increase of serum ketones occurred under all conditions, and the exercise respiratory quotient suggested some increase of fat utilization, WW (0.85) through CW (0.84) to CC (0.83). A fat loss of about 0.5 kg over the five days was confirmed by hydrostatic weighing and measurement of skinfold thicknesses. This was much less than the change previously observed in men, and moreover, it seemed to be independent of ambient conditions. Possible reasons why cold did not increase fat loss in these women include: a lower relative intensity of exercise; a greater stability of fat stores in women; avoidance of caffeine; a possible translocation of subcutaneous fat to deep fat depots; and a greater desire to "lose weight" irrespective of environmental conditions.

Adipose Tissue↗