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Biomedical subjects

H Johnson

Publications and source records attributed to H Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1997

Sustaining malaria prevention in Benin: local production of bednets.

Through a Benin-Canada participatory research initiative which included both Benin and Canadian non-governmental organizations, a local capacity to produce and market bednets for the prevention of malaria was developed. The development process began following a community-based assessment of local needs and skills. All materials for the manufacture and distribution of the bednets were obtained locally with the exception of the netting which was imported from Canada. The sustainability of the enterprise is enhanced by the community's recognition of the importance of malaria and the culturally acceptable practice of bednet use.

Benin↗
PubMed1997

Psychiatric aspects of temporal arteritis: a case report and review of the literature.

Temporal arteritis may present with atypical manifestations that can hamper its diagnosis. We report a case presenting with predominantly psychiatric symptoms including psychotic features and affective symptoms both on a background of cognitive impairment. Such clear-cut psychotic symptoms have not been described previously in the literature. Corticosteroid treatment was followed by full remission of psychotic and affective symptoms; treatment with antipsychotic medication was unnecessary. Temporal arteritis should be considered in the differential diagnosis of psychosis and affective disorder in the elderly. The erythrocyte sedimentation rate is a valuable parameter in the assessment of old-age psychiatry patients presenting both with functional and neurologic disorders.

Aged↗
PubMed1996

Neuropeptides and neurotrophin receptor mRNAs in primary sensory neurons of aged rats.

Neuropeptides and neurotrophin receptors are regulated in primary sensory neurons in response to axonal injury, and axonal lesions are characteristic stigmata of aging primary sensory neurons. We have therefore examined the expression of neuropeptides and neurotrophin receptor mRNAs in 30-month-old (median survival age) Sprague-Dawley rats to see if similar adaptive mechanisms operate in senescence. The content of neuropeptides was examined with immunohistochemistry (IHC) and in situ hybridization (ISH), and the cellular mRNA expression of neurotrophin receptors was studied with ISH. All of the aged rats had symptoms of hind limb incapacity (posterior paralysis), but fore limbs did not seem affected. The size-distribution of neuronal profiles in cervical and lumbar dorsal root ganglia (DRGs) was similar in aged and young adult (2-3 months old) rats. In aged rats, the DRG neurons showed an increase in both immunolabelling and mRNA content of neuropeptide tyrosine (NPY), as well as an increased cellular expression of galanin mRNA. In the same animals, there were decreased cellular levels of calcitonin gene-related peptide (CGRP; IHC and ISH) and substance P (SP; IHC and ISH), while the difference in neuronal somatostatin (IHC and ISH) was small. The distribution of neuropeptide immunoreactivities in the dorsal horn of the corresponding spinal cord segments revealed a decreased labelling for CGRP-, SP-, and somatostatin-like immunoreactivities (LI) in the aged rats at both cervical and lumbar levels. NPY- and galanin-LI had a similar distribution in aged and young adult rats. NPY-immunoreactive fibers were also encountered in the dorsal column of aged but not young adult rats. ISH revealed that most of the primary sensory neurons express mRNA for the p75 low-affinity neurotrophin receptor (p75-LANR) and that there was no discernible difference between young adult and aged rats. The labelling intensity for mRNA encoding high-affinity tyrosine kinase receptors (TrkA, TrkB, and TrkC) was decreased in aged rat DRG neurons, while the percentage of neuronal profiles expressing mRNA for TrkA/B/C was similar in young adult and aged rats. The changed pattern of neuropeptide expression in primary sensory neurons of aged rats resembled that seen in young adult rats subjected to axonal injury of peripheral sensory nerves and may, thus, indicate aging-related lesions of sensory fibers. Since NPY is primarily present in large and galanin in small DRG neurons, the stronger effect on NPY as compared to galanin expression may indicate that aging preferentially affects neurons associated with mechanoreception (A alpha and A beta fibers) as compared to nociceptive units (A delta and C fibers). Furthermore, the observed changes in neuropeptide expression were most pronounced in lumbar DRGs, that harbors the sensory neurons supplying the affected hindlimbs of the rats.

Adaptation, Physiological↗
PubMed1996

Pediatric injuries from cardiopulmonary resuscitation.

STUDY OBJECTIVE: To assess the type, rate, and severity of unanticipated complications of CPR (external cardiac compressions and ventilation) in a pediatric population. METHODS: A retrospective review was undertaken of the records from all deceased children ( < 12 years old) who had been given CPR during an 8-year period (1988 through 1995). Patients with historical or physical evidence of preceding trauma were excluded. Clinical and autopsy records were abstracted for patient demographics, clinical findings, duration of CPR, persons administering CPR, and medical examiner summaries. RESULTS: Two hundred eleven children (mean age, 19.0 months) met the inclusion criteria and were entered into the study. The most common cause of cardiac arrest was sudden infant death syndrome (56%), followed by drowning (8%), congenital heart disease (7%), and pneumonia (4%). Mean duration of CPR was 45 minutes (range, 3 to 180 minutes). Fifteen children (7%) had at least one injury as a result of CPR; 7 (3%) had injuries that were considered medically significant. These included retroperitoneal hemorrhage (n = 2), pneumothorax (n = 1), pulmonary hemorrhage (n = 1), epicardial hematoma (n = 1), and gastric perforation (n = 1); in spite of prolonged resuscitation performed with variable degrees of skill, only one patient was noted to have rib fractures. CONCLUSION: Significant iatrogenic injuries are rare in children who receive CPR; they occur in approximately 3% of cases. Recognizing the possibility of a complication may help in the management of children who survive cardiac arrest. Regardless of resuscitation history, abuse should be considered whenever traumatic injuries are encountered.

Cardiopulmonary Resuscitation↗
PubMed1996

Decreased expression of TrkB and TrkC mRNAs in spinal motoneurons of aged rats.

Several studies have indicated that a decrease in availability and/or responsiveness to neurotrophin(s) may be of importance in ageing and disease-related neurodegeneration. Using in situ hybridization we have studied the mRNA expression of the full-length neurotrophin receptors TrkB and TrkC in spinal cord motoneurons of aged rats (30 months old) with symptoms of hindlimb incapacity and in young adult rats (2-3 months old). The labelling intensity for TrkB of the individual cell profile was decreased by 25% (P < 0.001) in both the cervical and lumbar motor nuclei of aged rats. In thoracic motoneurons of aged and young adult rats the difference in expression of TrkB mRNA was smaller (down by 15%; P < 0.05). The labelling for TrkC mRNA was much weaker than that for TrkB in both aged and young adult rats, but TrkC mRNA expression also seemed to decrease. Comparison of the different motor nuclei along the spinal cord axis revealed that the motoneurons of the L6/S1 nuclei showed the strongest hybridization signal for the two Trk receptors in both aged and young adult rats. The possibility that a decrease in TrkB mRNA may contribute to age-related motor disturbances is discussed.

Aging↗
PubMed1995

Increase in alpha-CGRP and GAP-43 in aged motoneurons: a study of peptides, growth factors, and ChAT mRNA in the lumbar spinal cord of senescent rats with symptoms of hindlimb incapacities.

Sprague-Dawley rats develop progressive motor dysfunctions during the third year of life. We use this as a model to examine possible neuronal mechanism(s) that may cause motor impairments occuring during aging. In this study we have used indirect immunofluorescence histochemistry (IF) and in situ hybridization histochemistry (ISH) to study quantitatively and qualitatively the staining pattern and mRNA expression of calcitonin gene-related peptide (alpha-CGRP), growth-associated protein 43 (GAP-43), and acidic fibroblast growth factor (aFGF) in spinal lumbar motoneurons of young adult (2-3 months) and aged (30 months) Sprague-Dawley rats. In addition, mRNAs encoding choline acetyltransferase (ChAT), beta-CGRP, and cholecystokinin (CCK) were analyzed. All aged rats used in this study disclosed symptoms of hindlimb incapacity, ranging from mild weight-bearing insufficiency to paralysis of the hind limbs. The symptoms were confined to the musculature of the hindlimb and hip regions. Only a small number (approximately 15%) of the large motoneurons that innervate the hindlimb muscles were lost in those aged rats that had clinical symptoms of hindlimb motor incapacities. The remaining motoneurons expressed ChAT mRNA at levels similar to those of young adult rats. The vast majority of these motoneurons showed increased mRNA levels for alpha-CGRP and GAP-43. Aged motoneurons contained more CGRP like immunoreactivity (LI), but the number of immunoreactive neurons was smaller than in adult rats. GAP-43-LI could be detected in motoneurons in aged, but not in adult, rats. GAP-43-LI was always colocalized with CGRP-LI in aged motoneurons. Studies of individual aged rats revealed that the increase of GAP-43 mRNA-positive cell bodies occurred in cases with the most severe clinical symptoms, whereas the increase in alpha-CGRP was even evident in rats with mild symptoms. No alterations in content of aFGF-LI or aFGF mRNA could be detected in the aged rat, and the content of CCK and beta-CGRP mRNAs was also normal. The usefulness of this rat model for studies of neuromuscular aging and possible functional roles for GAP-43 and CGRP in plastic and regenerative processes during aging are discussed.

Aging↗
PubMed1995

Efficacy and safety of plateletpheresis by donors with low-normal platelet counts.

Our practice is to defer donors with blood platelet (PLT) counts of < 180 x 10(9)/L because PLT yields are low, when compared to PLT units collected from donors with higher counts. In an attempt to minimize deferral, we determined whether 33 donors, who repeatedly demonstrated low-normal PLT counts (150-180 x 10(9)/L) on multiple occasions during the prestudy period. might safely donate satisfactory apheresis PLT units simply by extending the apheresis collection time by 20 min (men) and 40 min (women). Repeat plateletpheresis procedures were scheduled at > or = 28-day intervals. The mean PLT yield (N = 92) was 5.8 x 10(11) with 97% of units containing > or = 4.0 x 10(11) PLTs. Although donors entered the study only after they had repeatedly exhibited predonation PLT counts of < 180 x 10(9)/L, PLT counts were not always below this level at the time of study collections. However, analyzing only donations with true predonation PLT counts of < 180 x 10(9)/L (N = 35), the mean PLT yield was excellent-5.4 x 10(11) with 97% of units containing > or = 4.0 x 10(11) PLTs. The average fall in donor blood PLT counts (pre-vs. postdonation) was 36%, with only ten of 99 postdonation counts being < 100 x 10(9)/L; the lowest was 69 x 10(9)/L. Thus, extending the apheresis collection time permitted donors who in the past were routinely deferred because of low PLT counts to safely donate satisfactory PLT units.

Blood Donors↗
PubMed1995

Computer-assisted video evaluation of surgical skills.

Compact video cameras have allowed the review of operations in self-directed learning sessions. Controlling the video viewing process by computer allows the selection of specific videotape segments containing the desired psychomotor skills to be evaluated--in this study, the steps involving laparoscopic tubal banding. Six faculty members were able to evaluate 23 videotapes efficiently without knowledge of the resident operator's identity. Because the computer allowed selection of only those frames of the videotape containing the skills to be evaluated, the duration of videotape seen was reduced by an average of 34% from the actual surgical time, with an increase in time saved as experience with the system was gained. Faculty members evaluated these events using a self-made checklist. It was possible to calculate the performance scores of each resident for the individual psychomotor skill components of the reviewed procedure. Computer-assisted video evaluation of surgical skills is technically feasible, allowing time-efficient review by multiple evaluators. With the development of psychometrically valid checklists for use with this technology, computer-assisted video evaluation of surgical skills may provide a new, innovative means of assessing surgical skills and training.

Clinical Competence↗
PubMed1995

Increased expression of serotonin transporter messenger RNA in raphe neurons of the aged rat.

The action of serotonin (5-hydroxytryptamine; 5HT) in the nervous system is terminated by reuptake of the neurotransmitter into the presynaptic nerve terminal via a plasma membrane-bound transporter protein. Recently, cDNAs encoding serotonin transporter protein were cloned. Using in situ hybridization we have studied the expression of serotonin transporter mRNA in the bulbospinal 5HT system of adult (2-3 months) and aged (30 months) rats. In adult rats, serotonin transporter mRNA labelled neurons were detected in the nucleus raphe obscurus, pallidus and magnus. In all aged rats, the optical density of the serotonin transporter mRNA labelling of individual cell profiles was increased by 20-30% (P < 0.001) when compared with adult rats. Five of the six aged rats studied had various degrees of hindlimb motor dysfunctions. In rats with the most pronounced signs of hindlimb motor dysfunction the number of labelled neurons was increased by 25-75% (P < 0.01) when compared with young adult rats. It is concluded that an increased serotonin transporter gene expression is present in the bulbospinal 5HT system of aged animals.

Aging↗
PubMed1995

MMR vaccination, measles epidemiology and sero-surveillance in the Republic of Ireland.

OBJECTIVE: Following the introduction of a national measles and subsequent MMR vaccination programme, to determine the susceptibility of 3-14-year-old children to measles, mumps and rubella and to relate the results to the epidemiology of measles and the need for vaccination policy changes. DESIGN: Cross-sectional sero-survey and trends in measles notifications and mortality. SETTING: Paediatric hospital outpatient departments in Dublin. SUBJECTS: Sera were collected from 837 children attending the clinics in 1991 and 1992. RESULTS: The prevalence of antibodies in children aged 3-6, 7-10 and 11-14 years was 84, 83 and 95% for measles; 48, 60 and 65% for mumps; and 78, 63 and 74% for rubella, respectively. The prevalence of mumps antibodies may be underestimated. Ninety-six per cent of girls aged 13-14 years had rubella antibodies. A widespread outbreak of measles occurred in 1993. Over recent years, an increasing proportion of measles notifications were in older children. CONCLUSION: Given sub-optimal uptake of MMR vaccine, outbreaks of infection in pre- and primary school children are inevitable. In such circumstances, a 2-shot MMR vaccine programme with high uptake is essential to prevent a shift of disease into older age groups.

Adolescent↗
PubMed1995

Shoulder dystocia--is it predictable?

An unmatched comparative study is described to determine if routine clinical indicators are useful predictors for shoulder dystocia. Parity, maternal weight gain during pregnancy, and a history of a previous large baby and increased operative vaginal delivery rate were more often associated with shoulder dystocia. No other significant associations were found. However, shoulder dystocia can not be predicted accurately antepartum using routinely available clinical factors.

Birth Injuries↗
PubMed1995

Tuberculin sensitivity and the BCG scar in tuberculosis contacts.

SETTING: Tuberculosis clinic, St Vincents Hospital, Dublin. OBJECTIVE: To determine the influence of past BCG vaccination on tuberculin sensitivity in tuberculosis contacts. DESIGN: Prospective cohort study of tuberculin sensitivity using the Mantoux technique (5 TU). RESULTS: In 1050 contacts of 96 cases of tuberculosis, BCG scars were noted in 76% of the contacts. Approximately 50%, 30% and 20% of the contacts respectively had negative (0-4 mm), positive (5-14 mm) and strongly positive (15+ mm) Mantoux responses. The presence of a BCG scar was not found to significantly influence the degree of tuberculin sensitivity. The degree of tuberculin sensitivity increased after 20 years and decreased after 60 years of age. Contacts of sputum-positive cases of tuberculosis had larger Mantoux responses. CONCLUSIONS: The study suggests that age of the contact and sputum status of the index case are important determinants of the degree of tuberculin sensitivity. Attributing a 'positive' Mantoux response to past BCG vaccination may be encouraging a false sense of security in contacts recently exposed to an infectious case of tuberculosis. Contact management guidelines may need to be reviewed and perhaps modified to reflect this finding.

Adolescent↗
PubMed1995

Tympanic membrane thermometry in the care of out-of-hospital patients.

STUDY OBJECTIVES: To determine the effectiveness of tympanic membrane (TM) thermometry in the out-of-hospital setting and to characterize the patients with abnormal out-of-hospital temperatures. DESIGN: Prospective, randomized, single-month study. SETTING: Inner city. PARTICIPANTS: Subjects transported by ambulance for whom consent was obtainable. RESULTS: TM probes set to rectal equivalent were assigned to three of the ambulance units of the local health department on randomly selected shifts during August 1992, one half at night and one half during the day. Simultaneous left and right ear temperatures at the scene and at the hospital, ambient temperatures, and patient's hospital temperatures were recorded. Other data recorded included each patient's mental status, activity level, and environment temperature. Paramedics noted whether they suspected a temperature problem before using the probe and whether any treatment was directed toward the patient's temperature. Regression, bias analysis, and chi 2 testing were performed; P was considered significant if it was less than .05. Right and left ear TM temperatures were correlated both at the scene and at the hospital (r = .91 and .92, respectively). TM temperatures and hospital temperatures were also correlated (r = .83 for right ear and .78 for left ear). Evaluation of agreement indicated that TM and hospital methods were equal, with a bias of -0.55 degrees F for oral and +0.66 degrees F for rectal temperatures. Thirty-two subjects (17%) were hyperthermic at the scene; of these, 9 of 32 (28%) were suspected before use of the probe. The paramedics initially treated 5 of the 9 suspected to have a temperature-related problem before using the probe and none of the 23 who were not suspected before using the probe (chi 2, P < .001). CONCLUSION: The TM probe functioned well despite a month of vigorous handling. Temperature correlation with the gold standard and between ears was acceptable in this setting. Presence of the probe did not help with the management of hyperthermic patients in this study.

Adolescent↗
PubMed1995

Long-term outcome of saliva-control surgery.

Thirty-nine patients who had undergone transposition of the submandibular ducts and unilateral ligation of a parotid duct for saliva control were followed up six years after surgery. Overall improvement was documented according to a drooling quotient, drooling severity and drooling frequency measures. Despite this superficially favourable outcome, a significant proportion of patients (39 per cent) or their caregivers had not found the surgery helpful. Complications included ranula formation, complaints of dry mouth, difficulty with swallowing, and changes in the consistency of oral secretions. More knowledge is needed of the likely outcomes of this procedure in individual patients, so that appropriate advice can be given and complications minimised.

Adolescent↗