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Biomedical subjects

M J Hall

Publications and source records attributed to M J Hall.

At least 19 recordsLinked to original sources
PubMed1998

Prevalence of traumatic myiasis in Hungary: a questionnaire survey of veterinarians.

Veterinarians in Hungary were asked to complete a questionnaire on traumatic myiasis; of the 664 veterinarians contacted, 247 replied (37.2 per cent) and of these 209 (84.6 per cent) reported myiasis to be a problem among the livestock they treated. Infestation levels of > 10 per cent of animals were reported in sheep, cattle and horses. The myiasis season lasted from March to November with most cases reported in July and August. Significantly more respondents reported that fly larvae were present deep in wounds rather than superficially, consistent with infestations due to the obligate parasite Wohlfahrtia magnifica (Diptera: Sarcophagidae). Frequent inspections and the treatment of infested animals were reported by 64.1 per cent of respondents as contributing to the economic impact of traumatic myiasis, and approximately half of the respondents (51.4 per cent) reported that inspections and treatments were carried out at least weekly during the summer. The most common form of treatment was the manual removal of larvae followed by topical application of insecticides, particularly organophosphates. More than half of the respondents (56.6 per cent) reported that there had been no change in the importance of myiasis over the last five to 10 years, but of those who reported a change, more reported an increase (28.3 per cent) than a decrease (15.2 per cent).

Animals↗
PubMed1998

Affective reactivity of speech in schizophrenia patients and their nonschizophrenic relatives.

This study compared levels of referential communication disturbance in speech samples from 41 stable schizophrenia outpatients, 46 parents of patients, and 23 nonpsychiatric control participants in affectively positive versus affectively negative conditions. The speech of the patients and parents showed elevated frequencies of reference failures in the affectively positive condition compared with control participants: the speech of the patients became more disordered in the affectively negative condition, whereas the speech of the parents did not. These results support the idea that referential communication disturbances reflect vulnerability, as well as overt illness, but that affective reactivity of these disturbances is associated mainly with the manifest illness. These findings are consistent with biological, cognitive, and psychological theories about the processes underlying stress responsiveness of schizophrenic symptoms more generally.

Adult↗
PubMed1998

Comparative scanning electron microscopy of third-instar Hypoderma spp. (Diptera: Oestridae).

Scanning electron microscope study of third-instar larvae of four species of Hypoderma revealed differences among species in the pattern of spination, spine morphology and morphology of the spiracular plates. These observations identify characters that enable the differentiation of Hypoderma actaeon and H. diana, parasitizing red deer (Cervus elaphus) in Europe, and provide additional characters for differentiating H. bovis and H. lineatum parasitizing cattle.

Animals↗
PubMed1998

Use of odour-baited sticky boards to trap tabanid flies and investigate repellents.

Tabanid flies were captured in a sheep pasture in Hungary using black plastic boards (30 x 30 cm), coated with an adhesive sheet, which were either unbaited or baited with ethane-ethiol or Swormlure-4. Five species of tabanid were caught, of which Tabanus tergestinus was caught in the greatest number (87% of 192). The sex ratio of T. tergestinus on unbaited boards was not statistically significantly different to equality. However, on baited boards, males were significantly more numerous, probably due to a repellent effect of the odours on female tabanids. Because of the importance of repellents in tabanid control, this result encourages the exploration of a wider range of compounds as tabanid repellents than are used at present. Sticky boards offer a simple technique for trapping both sexes of tabanids, especially males, which are poorly represented in many tabanid traps.

Animals↗
PubMed1998

Magnitude and time course of hemodynamic responses to Mueller maneuvers in patients with congestive heart failure.

To simulate the immediate hemodynamic effect of negative intrathoracic pressure during obstructive apneas in congestive heart failure (CHF), without inducing confounding factors such as hypoxia and arousals from sleep, eight awake patients performed, at random, 15-s Mueller maneuvers (MM) at target intrathoracic pressures of -20 (MM -20) and -40 cmH2O (MM -40), confirmed by esophageal pressure, and 15-s breath holds, as apneic time controls. Compared with quiet breathing, at baseline, before these interventions, the immediate effects [first 5 cardiac cycles (SD), P values refer to MM -40 compared with breath holds] of apnea, MM -20, and MM -40 were, for left ventricular (LV) systolic transmural pressure (Ptm), 1.0 +/- 1. 9, 7.2 +/- 3.5, and 11.3 +/- 6.8 mmHg (P < 0.01); for systolic blood pressure (SBP), 2.9 +/- 2.6, -5.5 +/- 3.4, and -12.1 +/- 6.8 mmHg (P < 0.01); and for stroke volume (SV) index, 0.4 +/- 2.8, -4.1 +/- 2.8, and -6.9 +/- 2.3 ml/m2 (P < 0.001), respectively. Corresponding values over the last five cardiac cycles were for LVPtm 6.4 +/- 4.4, 5.4 +/- 6.6, and -4.5 +/- 9.1 mmHg (P < 0.01); for SBP 6.9 +/- 4.2, -8.2 +/- 7.7, and -24.2 +/- 6.9 mmHg (P < 0.01); and for SV index -0. 4 +/- 2.1, -5.2 +/- 2.8, and -9.2 +/- 4.8 ml/m2 (P < 0.001), respectively. Thus, in CHF patients, the initial hemodynamic response to the generation of negative intrathoracic pressure includes an immediate increase in LV afterload and an abrupt fall in SV. The magnitude of response is proportional to the intensity of the MM stimulus. By the end of a 15-s MM -40, LVPtm falls below baseline values, yet SV and SBP do not recover. Thus, when -40 cmH2O intrathoracic pressure is sustained, additional mechanisms, such as a drop in LV preload due to ventricular interaction, are engaged, further reducing SV. The net effect of MM -40 was a 33% reduction in SV index (from 27 to 18 ml/min2), and a 21% reduction in SBP (from 121 to 96 mmHg). Obstructive apneas can have adverse effects on systemic and, possibly, coronary perfusion in CHF through dynamic mechanisms that are both stimulus and time dependent.

Adult↗
PubMed1997

Ambulatory surgery in the United States, 1995.

OBJECTIVES: This report presents estimates of surgical and nonsurgical procedures performed on an ambulatory basis in hospitals and freestanding ambulatory surgery centers in the United States during 1995. Data are presented by types of facilities, age, sex, and geographic region. Major categories of procedures and diagnoses are shown by age, sex, and region. METHODS: The estimates are based on data collected from the 1995 National Survey of Ambulatory Surgery conducted by the National Center for Health Statistics. The 1995 data were abstracted from 122,000 medical records in 489 hospitals and freestanding ambulatory surgery centers.

Adolescent↗
PubMed1997

Ambulatory surgery in the United States, 1994.

OBJECTIVES: This report presents estimates of surgical and nonsurgical procedures done on an ambulatory basis in hospitals and freestanding ambulatory surgery centers in the United States during 1994. Data are presented by types of facilities, age, sex, geographic region, and disposition for ambulatory surgery visits. Major categories of procedures and diagnoses are shown by age, sex, and region. METHODS: The estimates are based on data collected from the national Survey of Ambulatory Surgery, conducted for the first time in 1994 by the national Center for Health Statistics. The 1994 data were abstracted from 118,000 medical records in 494 hospitals and freestanding ambulatory surgery centers.

Adolescent↗
PubMed1997

Use of the ganciclovir implant for treating cytomegalovirus retinitis secondary to immunosuppression after bone marrow transplantation.

PURPOSE: To report a case in which we treated cytomegalovirus retinitis using an intravitreal ganciclovir sustained-release device in a patient negative for the human immunodeficiency virus, with a history of myeloproliferative syndrome with myelofibrosis and profound immunosuppression after allogeneic bone marrow transplantation. METHODS: Case report. Review of medical records and fundus photographs. RESULTS: After the ganciclovir device was implanted, the cytomegalovirus retinitis did not progress, and visual acuity improved. We removed the device 9 months after implantation. CONCLUSIONS: The ganciclovir sustained-release device may be useful for treating cytomegalovirus retinitis in patients without the acquired immunodeficiency syndrome who are profoundly immunosuppressed and fail conventional intravenous therapy. If immune suppression is of limited duration, the device can be removed.

Antiviral Agents↗
PubMed1997

Wound myiasis of sheep in Hungary.

In Hungary, 4388 sheep in six flocks were surveyed in June-August of 1992-1995 to gather basic data on wound myiasis, its incidence, the predominant fly species involved and the clinical manifestations of infestation. The pathogenesis and economic significance of wound myiasis, as well as the interrelation of breed and sex with infestation levels, were evaluated. Active wound myiasis was recorded in all flocks, in 17.6% (774/4388) of the inspected sheep. The incidence varied among flocks and inspections from 4.7% to 38.9%, but it was significantly greater in imported breeds (28.8%, 651/2257) than in indigenous breeds (5.8%, 123/2131). Lesions of wound myiasis were located more frequently on the external genital organs (in 87%, 673/774 of all cases) than on other body regions. Overall, significantly more males (74.3%, 61/82) than females (16.5%, 713/4306) were infested. With the exception of five cases (0.06% of the total), when larvae of Lucilia sericata (Diptera: Calliphoridae) were also found, Wohlfahrtia magnifica (Diptera: Sarcophagidae) was the only species identified in wounds in this study. Despite the fact that larvae of L. sericata were so rarely encountered in wounds, adults of L. sericata were much the more common of the two species observed around wounds, even those infested by W. magnifica. The vast majority of animals inspected had only one myiasis wound. Clinical signs depended on the body part affected. The most severe infestations, in terms of extent of wounds and numbers of visible larvae, were usually those of the vulva and prepuce. Wound consisted of from one up to six foci, each completely filled by larvae of W. magnifica. These foci were either isolated from each other or they merged into a large lesion. Larvae in any focus tended to be at the same stage of development, but, were wounds were very severe, a range of developmental stages was observed together, indicating that frequent restrikes of wounds occurred. The most common signs were restlessness, anxiety and reluctance to graze. The animals were obviously depressed when they suffered from severe infestations causing lameness or blindness. Some of the most severely affected animals displayed obvious loss of condition. However, overall, there was no significant difference between the mean bodyweights of a sample of infested (59.2 kg) and uninfested (60.9 kg) animals.

Animals↗
PubMed1997

Left ventricular volume in patients with heart failure and Cheyne-Stokes respiration during sleep.

In patients with congestive heart failure (CHF), elevated, left ventricular (LV) volume might lead to pulmonary congestion and hypocapnia, which would create a predisposition to the development of Cheyne-Stokes respiration with central sleep apnea (CSR-CSA). In addition, because LV volume affects cardiac output, it should influence the lengths of hyperpneas. We therefore evaluated LV volumes and transcutaneous PCO2 (PtcCO2) during wakefulness and stage 2 sleep in 16 patients with CHF due to nonischemic dilated cardiomyopathy (NIDC). Data were then compared between those with (n = 7) and those without CSR-CSA (n = 9). LV end-diastolic volume (LVEDV) was significantly higher in patients with than those without CSR-CSA (585 +/- 118 versus 312 +/- 41 ml, p < 0.05). Compared with patients without CSR-CSA, those with CSR-CSA had lower mean stage 2 sleep PtcCO2 (36.3 +/- 2.2 versus 41.2 +/- 1.2 mm Hg, p < 0.05) and a lesser change in PtcCO2 from wakefulness to stage 2 sleep (-0.4 +/- 0.3 versus 2.0 +/- 0.4 mm Hg, p < 0.001). Among patients with CSR-CSA, hyperpnea length was inversely related to LVEDV (R = 0.769, p = 0.043) owing to the direct relationship of cardiac output to LVEDV (R = 0.791, p = 0.034). We conclude that CSR-CSA in patients with CHF due to NIDC is associated with increased LV volumes possibly through the direct or indirect influence of LV volume on PaCO2 and cardiac output.

Carbon Dioxide↗
PubMed1997

Traumatic myiasis of sheep in Europe: a review.

The two most important fly species causing traumatic cutaneous myiasis of sheep in Europe are Wohlfahrtia magnifica (Diptera: Sarcophagidae), which causes a form of myiasis known as wound myiasis, mainly in southern and eastern Europe, and Lucilia sericata (Diptera: Calliphoridae), which causes sheep strike, mainly in the middle latitudes of Europe. Other calliphorid blow-flies play a role mainly as secondary agents of myiasis, but in northern latitudes the L. caesar/illustris group are primary agents. Infestation levels vary greatly from region to region depending on a wide range of factors related to the composition of the parasite fauna, the host, animal husbandry and control practices, climate and geography. In some areas of Europe there have been recent increases in the incidence of traumatic myiasis due to changes in some of the previously mentioned factors. However, in other areas the incidence of myiasis is apparently low. More studies are needed to resolve this unclear situation and to explain regional differences. A number of areas for future research are highlighted including predicting the impact of environmental change, population modelling and development of novel control strategies.

Animal Husbandry↗
PubMed1996

Probing conserved regions of the cytoplasmic LOOP1 segment linking transmembrane segments 2 and 3 of the Saccharomyces cerevisiae plasma membrane H+-ATPase.

Genetic probing was used to examine conserved amino acid clusters in the first cytoplasmic loop domain (LOOP1) linking transmembrane segments 2 and 3 of the plasma membrane H+-ATPase from Saccharomyces cerevisiae. Deletion of the LOOP1 region in PMA1 resulted in a defective enzyme. Scanning alanine mutagenesis of conserved residues produced lethal cell phenotypes in 14 of 26 amino acids, suggesting major enzyme defects. Most viable mutants showed growth characteristics that were comparable to wild type. Two mutations, I183A and D185A, produced reduced growth rates, hygromycin B resistance, and low pH sensitivity, which are phenotypes associated with defects in the H+-ATPase. However, both mutant enzymes displayed near-normal kinetics for ATP hydrolysis in vitro. Localized random mutagenesis was also performed at sites Glu195, Val196, and Ile210, which all showed lethal phenotypes upon conversion to alanine. Amino acids with polar side groups could substitute for Glu195, while Val196 could not tolerate polar side group moieties. Nine mutations at Ile210 proved lethal, including K, R, E, P, H, N, V, G, and A, while functional enzyme was obtained with S, C, M, and L. Normal rates and extents of pH gradient formation were observed for all mutant enzymes, except I183A and D185A. Detailed analysis of the I183A enzyme indicated that it hydrolyzed ATP like wild type, but it appeared to inefficiently couple ATP hydrolysis to proton transport. In total, these results affirm that conserved amino acids in LOOP1 are important to H+-ATPase function, and purturbations in this region can alter the efficiency of energy coupling.

Alanine↗
PubMed1996

Probing the cytoplasmic LOOP1 domain of the yeast plasma membrane H(+)-ATPase by targeted factor Xa proteolysis.

The cytoplasmic domain linking transmembrane segments 2 and 3 (LOOP1) of the yeast H(+)-ATPase was probed by the introduction of unique factor Xa recognition sites. Three sites, I170EGR, I254EGR and I275EGR, representing different structural regions of the LOOP1 domain, were engineered by site-specific mutagenesis of the PMA1 gene. In each case, multiple amino acid substitutions were required to form the factor Xa sites, which enabled an analysis of clustered mutations. Both I170EGR and I275EGR-containing mutants grew at normal rates, but showed prominent growth resistance to hygromycin B and sensitivity to low external pH. The engineered I254EGR site within the predicted beta-strand region produced a recessive lethal phenotype, indicating that mutations G254I and F257R were not tolerated. Mutant I170EGR- and I275EGR-containing enzymes showed relatively normal Km and Vmax values, but they displayed a strong insensitivity to inhibition by vanadate. An I170EGR/I275EGR double mutant was more significantly perturbed showing a reduced Vmax and pronounced vanadate insensitivity. The I170EGR site within the putative alpha-helical stalk region was cleaved to a maximum of 10% by factor Xa under non-denaturing conditions resulting in a characteristic 81 kDa fragment, whereas the I275EGR site, near the end of the beta-strand region, showed about 30-35% cleavage with the appearance of a 70 kDa fragment. A I170EGR/I275EGR double mutant enzyme showed about 55-60% cleavage. The cleavage profile for the mutant enzymes was enhanced under denaturing conditions, but was unaffected by MgATP or MgATP plus vanadate. Cleavage at the I275EGR position had no adverse effects on ATP hydrolysis or proton transport by the H(+)-ATPase making it unlikely that this localized region of LOOP1 influences coupling. Overall, these results suggest that the local region encompassing I275EGR is accessible to factor Xa, while the region around I170EGR appears buried. Although there is no evidence for gross molecular motion at either site, the effects of multiple amino acid substitutions in these regions suggest that the LOOP1 domain is conformationally active, and that perturbations in this domain affect the distribution of conformational intermediates during steady-state catalysis.

Amino Acid Sequence↗
PubMed1996

Genetic probing of the first and second transmembrane helices of the plasma membrane H(+)-ATPase from Saccharomyces cerevisiae.

Structural features of the putative helical hairpin region comprising transmembrane segments 1 (TM1) and 2 (TM2) of the yeast plasma membrane H(+)-ATPase were probed by site-directed mutagenesis. The importance of phenylalanine residues Phe-116, Phe-119, Phe-120, Phe-126, Phe-144, Phe-159, and Phe-163 was explored by alanine replacement mutagenesis. It was found that substitutions at all positions, except Phe-120 and Phe-144, produced viable enzymes, although a range of cellular growth phenotypes were observed like hygromycin B resistance and low pH sensitivity, which are linked to in vivo action of the H(+)-ATPase. Lethal positions Phe-120 and Phe-144, could be replaced with tryptophan to produce viable enzyme, although the F144W mutant was highly perturbed. ATP hydrolysis measurements showed that Km was not significantly altered for most mutant enzymes, whereas Vmax was moderately reduced with two mutants, F144W and F163A, showing less than 50% of the normal activity. Double Phe-->Ala mutations in TM1 and TM2 were constructed to examine whether such substitutions would result in a higher degree of enzyme destabilization. Mutant F116A/F119A was viable and gave a normal phenotype, while F159A/F163A was not viable. Other double mutants, F116A/F159A and F119AF/159A, which are predicted to lie juxtaposed on TM1 and TM2, produced non-functional enzymes. However, a viable F119V/F159A mutant was isolated and showed hygromycin B resistance. These results suggest that double mutations eliminating 2 phenylalanine residues strongly destabilize the enzyme. A putative proline kink at Gly-122/Pro-123 in TM1 is not essential for enzyme action since these residues could be variously substituted (G122A or G122N; P123A, P123G, or P123F) producing viable enzymes with moderate effects on in vitro ATP hydrolysis or proton transport. However, several substitutions produced prominent growth phenotypes, suggesting that local perturbations were occurring. The location of Pro-123 is important because Gly-122 and Pro-123 could not be exchanged. In addition, a double Pro-Pro created by a G122P mutation was lethal, suggesting that maintenance of an alpha-helical structure is important. Other mutations in the hairpin, including modification of a buried charged residue, E129A, were not critical for enzyme action. These data are consistent with the view that the helical hairpin comprising TM1 and TM2 has important structural determinants that contribute to its overall stability and flexibility.

Cell Membrane↗
PubMed1996

Efficacy of ivermectin and moxidectin injection against larvae of Wohlfahrtia magnifica (Diptera: Sarcophagidae) in sheep.

The therapeutic efficacies of ivermectin (Ivomec injection, Merck Sharp & Dohme B.V.) and moxidectin (Cydectin 1% injection, American Cyanamid Company) were evaluated in sheep naturally infested with larvae of Wohlfahrtia magnifica. Sheep were randomly allocated to one of the 2 groups, each consisting of 19 animals. Sheep in one group received ivermectin and those in the other, moxidectin by subcutaneous injection at a dose of 0.2 mg/kg body weight. Evaluation was performed at 19, 24, 28, 39, 43, 48, 52, 63, 67, 72, 87, 96, 120, 144 and 168 h after treatment. At 144 and 168 h post-treatment, late third-instar larvae were collected from wounds of four sheep in both groups and from untreated, infested sheep. These larvae were reared in the laboratory to assess adult emergence. Neither ivermectin nor moxidectin was effective as a rapid acting treatment or as a long-term, or even short-term, prophylactic. Despite the treatment, 30-40% of sheep had live larvae at every evaluation. Although larvae disappeared from the wounds of some sheep in both groups after the treatment, the wounds in these animals failed to recover and were reinfested by larvae of W. magnifica. On day 7 post-treatment the trial had to be finished because the majority of treated sheep were severely infested by Wohlfahrtia maggots. The average number of infested sheep in the two groups and the number of adults that were produced from larvae collected from treated sheep indicate that ivermectin and moxidectin did not differ significantly in efficacy.

Animals↗
PubMed1996

Cycle length of periodic breathing in patients with and without heart failure.

Because apnea length during periodic breathing varies according to the preceding increase in ventilation and reduction in PaCO 2, differences in the cycle length of periodic breathing among patients with normal and impaired cardiac function might be explained by the influence of lung-to-carotid body circulatory delay, as reflected by lung-to-ear circulation time (LECT), on hyperpnea length rather than on apnea length. It was therefore hypothesized that circulatory delay is an important determinant of periodic-breathing hyperpnea length but not apnea length. To test this hypothesis, LECT, periodic-breathing cycle length, apnea length, and hyperpnea length were compared in 10 patients with idiopathic central sleep apnea (ICSA), whose cardiac function was normal, as opposed to 10 with Cheyne-Stokes respiration and central sleep apnea (CSR-CSA) in association with congestive heart failure (CHF). As compared with ICSA patients, cycle length was significantly longer in patients with CSR-CSA (37.3 +/- 3.0 s versus 59.0 +/- 4.9 s, p < 0.005). This difference was due to significantly longer hyperpnea length in the CSR-CSA patients (16.7 +/- 2.8 s versus 36.7 +/- 3.4 s, p < 0.001), since apnea length was similar in the two groups. In addition, LECT was longer in the CSR-CSA patients (24.3 +/- 2.0 s versus 10.3 +/- 1.0 s, p < 0.001), and correlated strongly with cycle length (r = 0.88, p < 0.001) and hyperpnea length (r = 0.90, p < 0.001) but not with apnea length. LECT correlated inversely with cardiac output (r = -0.72, p < 0.006), indicating that LECT is a valid measure of circulatory delay. Thus, circulatory delay is an important determinant of hyperpnea length but not of apnea length in patients with ICSA and CSR-CSA.

Cardiac Output↗
PubMed1996

Patients, carers and the medical profession: a co-operative approach.

This article is reprinted (with minor editing) from the Queensland Council of Carers newsletter for members. The Council's Public Policy Forum, held in September 1994, raised problems faced by carers, some of which related to the relationship between patients, carers, and the medical profession. Their concerns were circulated to the Divisions of General Practice, who in turn delegated the author to contact the Queensland Council of Carers, with a view to improving co-operation and clarifying mutual expectations.

Caregivers↗