Biomedical subjects
J Montgomery
Publications and source records attributed to J Montgomery.
Law, coercion, and the public health.
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Physiological characterization of lateral line function in the Antarctic fish Trematomus bernacchii.
The Antarctic notothenioids are a monophyletic radiation of fishes that have evolved under conditions of low light and cold, where non-visual sensory systems, such as the mechanosensory lateral line system, would be of importance. As part of a study of the structure and function of the mechanosensory lateral line system in these fishes we systematically characterized the function of the anterior lateral line system in one of the common benthic species, Trematomus bernacchii. Frequency-response and threshold-tuning curve methods yield similar functional characterizations of single afferent fibre responses to vibrational stimulation. Curve fitting of generalized transfer function to frequency-response curves allows an objective splitting of responses into velocity and acceleration sensitive populations thought to correspond to superficial and canal neuromasts, respectively. Both response types are characterized by a low-pass frequency-response curve, with a relatively low upper frequency cut-off when compared with data from temperate species. The sensitivity of the lateral line system of T. bernacchii is comparable to that of the mottled sculpin Cottus bairdi.
Fibers innervating different parts of the lateral line system of an Antarctic notothenioid, Trematomus bernacchii, have similar frequency responses, despite large variation in the peripheral morphology.
Regional differences in the architecture and size of lateral line canals and neuromasts were measured in an Antarctic fish, Trematomus bernacchii, and the data were used in models of canal and cupular mechanics to predict the frequency response of these two peripheral structures. These modeled predictions were then compared to frequency response functions measured with single unit recording techniques from anterior and posterior lateral line fibers innervating different canals on the head and trunk of fish of various sizes. Despite large variations in the peripheral morphology of head and trunk canals in fish of different sizes, lateral line fibers were relatively homogeneous in their frequency response properties. In response to stimuli of equal pk-pk acceleration levels, all canal neuromast fibers responded with equal and maximum responsiveness in the 10-45 Hz range, after which responsiveness fell off at about 18 dB/octave. Whereas the biomechanical models of cupular and canal responsiveness predicted the region of equal and maximum responsiveness in the 10-45 Hz range, they did not predict the high frequency cutoff nor the slope. Rather, these models predicted responsiveness out to at least 540 Hz, and a high frequency slope of 12 dB/octave. In terms of the frequency response of peripheral fibers, we conclude that (1) there can be considerable morphological variability, with little consequence for function, as long as some minimum standards for maintaining constant acceleration responsiveness in the 10-45 Hz range are met, and (2) there must be additional filters between the cupula and primary afferent fibers.
A case of spontaneous hypothermia.
It is important to recognise any condition, however rare, which can be cured. We report a case of chronic hypothermia and its dramatic response to treatment.
Leptospires isolated from toads and frogs on the Island of Barbados.
Four pathogenic strains of leptospires were isolated from the kidneys of toads (Bufo marinus) and seven from frogs (Eleutherodactylus johnstonei). Isolates from two toads and one frog belonged to serovar bim, the causative agent of most cases of severe leptospirosis on Barbados. The other eight strains belonged to a new serovar within the Australis serogroup. The name bajan is proposed for this new serovar of Leptospira interrogans.
The bacteriology of acute pneumonia and meningitis in children in Papua New Guinea: assumptions, facts and technical strategies.
Acute respiratory infections in children aged less than 5 years in the Eastern Highlands of Papua New Guinea were investigated bacteriologically for 10 years from November 1978. Haemophilus influenzae and Streptococcus pneumoniae were responsible for 73% of all bacteria cultured from lung aspirate (83 samples), 85.5% from blood (1024 samples) and 92% from cerebrospinal fluid (155 samples). Nonencapsulated H. influenzae was carried by up to 90% of children and was the predominant haemophilus type cultured from lung tissue. Mixed infections of the lung with two types of H. influenzae (8 cases) and both H. influenzae and S. pneumoniae (18 cases), commonly together with other organisms of questionable pathogenicity, reflected the proximity of this organ to the upper respiratory tract. Serotype b accounted for 62% and 82% of H. influenzae isolated from bacteraemic pneumonia and meningitis cases, respectively. Polymicrobic bacteraemic pneumonia occurred in 16 children. Both H. influenzae and S. pneumoniae establish dense, unregulated long-term colonization in the nasopharynx during the neonatal period. Each inhibit autochthonous microflora by mechanisms that are currently unclear. Infections with two or more types occur in 30% (S. pneumoniae) and 60% (H. influenzae) of carriage-positive children. 70-75% of H. influenzae and S. pneumoniae isolates from blood concomitantly colonize the upper respiratory tract. Intense exposure of Papua New Guinean children to penicillin at all levels of health care since the 1940s has resulted in widespread relative resistance among pneumococci to this antibiotic. Resistant strains are now found in 32 serotypes, and in children penicillin resistance is present in 75% of all carriage strains and 52% and 22% of blood and cerebrospinal fluid isolates, respectively. Penicillin-susceptible and resistant pneumococcal serotypes commonly coexist in multiply populated carriage sites. Resistance to betalactam antibiotics is rare among H. influenzae strains and resistance has not been detected in either H. influenzae or S. pneumoniae to chloramphenicol, erythromycin, tetracycline or cotrimoxazole. It should not be assumed that the technology of respiratory bacteriology as it is practised in developed countries can be transferred to the third world for utilization in paediatric aetiology and carriage studies. Respiratory bacteriology strategies as they evolved in Goroka were subject to diverse influences. The type distribution of the major causative agents defied fashionable beliefs, generated the need for more precise epidemiological differentiation and, by virtue of their carriage density, cultural properties and response to commonly used antibiotics, required the introduction or development of compatible diagnostic procedures.
Depression and the menopause.
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Antimicrobial susceptibility patterns of Haemophilus isolates from children in eleven developing nations. BOSTID Haemophilus Susceptibility Study Group.
The antimicrobial susceptibilities of 426 isolates of Haemophilus species, which were collected as part of a worldwide study of the etiology of acute respiratory disease in children in selected developing countries, were determined. Eleven antibiotics were tested using the recently described Haemophilus Test Medium. There was a low prevalence of antibiotic resistance; 6% of strains were resistant to ampicillin, and 1.6% were resistant to chloramphenicol. Strains resistant to both ampicillin and chloramphenicol were recovered only from Thailand. Susceptibility to penicillin G was also determined; the minimum inhibitory concentrations for penicillin and ampicillin were concordant within one 2-fold dilution in 97% of the isolates. Thus, Haemophilus isolates were as susceptible to penicillin G as they were to ampicillin, and penicillin resistance was infrequent overall. These data provide support for the current protocols for the management of acute respiratory infections in children in developing countries, in which penicillin G is a first-line agent.
Pneumonia in children in the Eastern Highlands of Papua New Guinea: a bacteriologic study of patients selected by standard clinical criteria.
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Low plasma beta-endorphin in post-traumatic stress disorder.
We compared serum cortisol, ACTH and plasma beta-endorphin in 21 Post-Traumatic Stress Disorder patients and 20 controls. Although we found no important disturbance in diurnal rhythms, the PTSD patients had significantly higher A.M. serum cortisols compared with controls. Both A.M. and P.M. plasma beta-endorphins in PTSD patients were significantly lower compared with controls. These data suggest that plasma beta-endorphin may be a marker for PTSD and that chronic endogenous opioid depletion may play a role in the pathogenesis and perpetuation of this disorder.
Isolation of Fusobacterium nucleatum and electron microscopic observations of spirochetes from tropical skin ulcers in Papua New Guinea.
Tropical ulcer is a disabling condition of the lower leg affecting mainly young adults and older children. Microscopic observations of lesion material have shown fusiform bacilli and spirochetes. We used anaerobic culture techniques to isolate and identify these fusiform bacilli. Electron microscopic (EM) studies were performed to characterize the spirochetes. Material collected on swabs was used to inoculate pre-reduced media and to prepare smears for gram staining; the swabs were placed in fixative for EM study. After incubation, colonies containing fusiform bacilli were subcultured. The anaerobic gram-negative fusiform isolates were identified as Fusobacterium nucleatum using biochemical reactions, hemagglutination testing, and reaction of antigen preparations of the isolates and ATCC strains in serological tests with rabbit antisera. EM observations of negatively stained spirochetes revealed an 8-16-8 periplasmic flagellar arrangement. F. nucleatum and spirochetes may participate in the pathogenesis of this polymicrobic infection.
Multiple colonization of the upper respiratory tract of Papua New Guinea children with Haemophilus influenzae and Streptococcus pneumoniae.
Nasal secretions from Papua New Guinea children were cultured using selective agents, to determine the prevalence of multiple colonization for both S. pneumoniae and H. influenzae. 29.5% of 156 and 53% of 93 carriage positive subjects harbored more than one type of S. pneumoniae and H. influenzae respectively. Of 95 strains of pneumococci isolated from multiply colonized children, 40% were relatively resistant to benzylpenicillin. In more than one half of the children in this group both penicillin sensitive and resistant serotypes coexisted. Significantly more penicillin resistant pneumococci were isolated from children with ready access to primary and regional health care services. Among H. influenzae the prevalence of multiple isolations due to nonencapsulated variants only, and encapsulated plus nonencapsulated organisms was similar. The commonest biotypes were types I, II, III and V, and each was similarly associated with multiple carriage.
Postpartum depression: a clinical view.
Recent studies identify a much higher incidence of postpartum depression than had previously been acknowledged and show that a mother's depression may have a highly deleterious effect on the early development of her infant. Although a variety of theories exist concerning the etiology of postpartum depression, many writers now accept a transactional model of causality. This article suggests that for many women early depriving or abusive experiences are necessary but not sufficient conditions to explain the development of severe postpartum depression. Four different types of postpartum depression are presented with widely differing prognoses and needs for treatment. It is suggested that a wide range of treatment modalities may be needed with the more serious depressions and that such services are lacking in most communities.
Penicillin-resistant Streptococcus pneumoniae and other nasal bacteria among children in remote areas of the fringe highlands of Papua New Guinea.
The nasal bacteriology of children in two areas of the western Schrader Range was studied. One area, served by an aid post since 1976, was compared with the other, which received its first medical care in 1984. Significant differences in the amount of resistance to penicillin were found, but not in the direction expected. These anomalous findings are interpreted in light of the particular histories of the groups involved, suggesting the transmission of resistant strains through contact among children.
Skeletal effects of oral oestrogen compared with subcutaneous oestrogen and testosterone in postmenopausal women.
STUDY OBJECTIVE: To compare oral and implanted oestrogens for their effects in preventing postmenopausal osteoporosis. DESIGN: Non-randomised cohort study of postmenopausal women treated with oral or depot oestrogens and postmenopausal controls. SETTING: Gynaecological endocrine clinic in tertiary referral centre. PATIENTS: Oral treatment group of 37 postmenopausal women (mean age 57.5 years, median 8.75 years from last menstrual period), compared with 41 women given oestrogen implants (mean age 56.2 years, median 9.5 years from last menstrual period) and 36 controls (mean age 51.8 years, median 2.0 years from last menstrual period). Weight was not significantly different among the groups. INTERVENTIONS: Oral treatment group was given continuous treatment with cyclic oestrogen and progesterone preparations (Prempak C or Cycloprogynova) for a median of 8.0 years. Implant group was given subcutaneous implants of oestradiol 50 mg combined with testosterone 100 mg, on average six monthly for a median of 8.5 years. Controls were not treated. END POINT: Significant increase in bone density. MEASUREMENTS AND MAIN RESULTS: Bone density measured by dual beam photon absorptiometry was 1.02 (SD 0.13) g hydroxyapatite/cm2 in implant group versus 0.89 (0.11) in oral group (p less than 0.01) and 0.87 (0.14) in controls (p less than 0.01). Serum oestradiol concentration in implant group was (median) 725 pmol/l versus 170 pmol/l in oral group (p less than 0.01) and 99 pmol/l in controls (p less than 0.01). Serum follicular stimulating hormone was median 1 IU/l (range 1-11) in implant group (equivalent to premenopausal values) versus 43 (4-94) IU/l in oral group (p less than 0.01) and 72 (28-99) IU/l in controls (p less than 0.01). CONCLUSIONS: Subcutaneous oestrogen is more effective than oral oestrogen in preventing osteoporosis, probably owing to the more physiological (premenopausal) serum oestradiol concentrations achieved. It also avoids problems of compliance that occur with oral treatment.
Indirect voltammetric and atomic absorption spectrometric determination of caffeine.
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The effect of vaginal delivery on the urethral sphincter.
To investigate the aetiological role of vaginal delivery in genuine stress incontinence we compared two groups of women who underwent full urodynamic assessment in our department. The women in the first group had competent urethral sphincter mechanisms and those in the second group had genuine stress incontinence. There were no differences between the two groups in respect of parity, number of vaginal deliveries or birthweight of the heaviest baby. The group with competent urethral sphincter mechanisms did show some evidence to implicate an increased number of vaginal deliveries in poor function of the distal part of the urethral sphincter mechanism.