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Biomedical subjects

H Johnson

Publications and source records attributed to H Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1999

Expression of p75(NTR), trkB and trkC in nonmanipulated and axotomized motoneurons of aged rats.

Several lines of evidence indicate that adult neurons remain dependent on neurotrophins and that changes in tissue expression of neurotrophins and/or their receptors may play a role in senile neurodegeneration. We have studied the expression of p75NTR, trkB and trkC, respectively, in lumbar motoneurons of young adult (2-3 months) and aged (30 months) rats subjected to sciatic transection using in situ hybridization and immunohistochemistry. Nonmanipulated age-matched animals were processed in parallel. In nonmanipulated aged rats, high levels of p75NTR could be seen in a number of motoneurons (10-15%), while in young adult animals no p75NTR could be detected. Seven days following sciatic axotomy, a conspicuous ipsilateral upregulation p75NTR was observed in young adult rats. Also in aged rats there was a marked ipsilateral increase in number of p75NTR expressing neurons ( approximately 100%). In comparison to young adult rats, aged rats showed a decreased expression of both trkB (5/6 animals) and trkC (6/6 animals). Furthermore, in response to sciatic transection, 3 out of 5 aged rats did not show an increased expression of trkB. In aged rats, axotomy did not induce any significant change in trkC expression. In the young adult rats, we recorded a side-to-side effect with lower values ipsilaterally, however, it cannot be excluded that this difference was caused by an upregulation in the contralateral motoneurons. Oligonucleotide probes against BDNF and NT3 mRNA showed only very few faintly positive neurons in both age groups. Our results indicate that the pattern of regulatory changes of NT receptors in response to axotomy is different in aged and young adult rats. The lack of covariation between p75NTR and trkB and trkC regulation in aged rats indicates a changed role for p75NTR in senescent motoneurons.

Aging↗
PubMed1999

Treatment of intracorporeal injection nonresponse with sildenafil alone or in combination with triple agent intracorporeal injection therapy.

PURPOSE: We assess the efficacy of sildenafil as salvage therapy for intracorporeal injection therapy nonresponse. MATERIALS AND METHODS: The study group comprised 93 patients with a mean age of 53.6 years (range 24 to 77) with chronic erectile dysfunction. In all cases a home trial of intracavernosal injection of high dose alprostadil and triple agent intracavernosal injection therapy had failed. Patients were treated with sildenafil citrate alone or in combination with intracavernosal injection therapy. RESULTS: The etiology of erectile dysfunction was arteriogenic in 29 cases, cavernosal venous leakage in 36, mixed vasculogenic in 24, psychogenic in 3 and post-priapism intracavernous fibrosis in 1. Of the 32 sildenafil responders (34% of the study group) 30 required 100 and 2 required 50 mg. The 29 sildenafil intracavernosal injection (combined therapy) responders (31% of the study group) required 100 mg. sildenafil. There were 32 nonresponders (34% of the study group). Mean International Index of Erectile Function questions 3 and 4 scores were 1.7 and 1.5 at baseline, 2.3 and 1.9 with intracavernosal injection, 4.6 and 42.2 with sildenafil, and 4.1 and 4.10 with combined therapy, respectively. Of the 93 patients 29 (31%) treated with intracavernosal injection reported adverse effects, including penile pain in 27, dizziness in 5 and headache in 2. Of the patients treated with sildenafil 34 (37%) reported side effects, including headache in 30, facial flushing in 25, dyspepsia in 12, nasal congestion in 9, dizziness in 5 and visual disturbances in 1. Of the 41 patients given combined therapy 20 (49%) reported adverse effects, including penile pain in 15, headache in 15, facial flushing in 12, dyspepsia in 7, nasal congestion in 3, dizziness in 12 and syncope in 1. CONCLUSIONS: Sildenafil alone or sildenafil plus intracavernosal injection is effective salvage therapy for intracavernosal injection nonresponse. Sildenafil in combination with intracavernosal injection is associated with a 33% incidence of adverse effects, including a 20% incidence of dizziness.

Adult↗
PubMed1999

Determinants of the Permethrin Impregnated Bednets (PIB) in the Republic of Benin: the role of women in the acquisition and utilization of PIBs.

An important aspect of malaria control strategies has been the use of prophylactic measures such as impregnated bednets; however, adoption of this strategy has been slow and uneven. This study considers the factors determining Permethrin Impregnated Bednets (PIB) use in the context of a PIB promotion project in a rural area of Benin undertaken between 1992 and 1995. Quantitative data, on socio-demographic characteristics, malaria knowledge, attitudes, and practices, were gathered from 191 households of PIB users and non-users for comparative purposes using a questionnaire format. Qualitative data were collected from 23 focus group discussion sessions and 16 semi structured interviews. Women's income, men's educational level, and women's participation in communal organizations were the principal variables distinguishing user households from non-user households. Recourse to non-western medicine and, in particular, to medicinal teas which are considered preventive or curative correlates negatively with PIB use. The qualitative data shows that informants consider exposure to the sun, especially while engaged in agriculture work, a principal cause of malaria, and that PIB adoption is not considered justified in a context where there is a quasi chronic shortage of financial resources and where confidence in the efficacy of non-western medicine prevails. Because they have primary responsibility for the health of their families and are more aware of children's vulnerability to malaria, women are more inclined than men to want to buy PIBs. However, because the household head, who is most often male, sets family consumption priorities using family income, women often have to resort to using their own income, which is often considerably lower than that of men, to buy PIBs. Support for community initiatives which are directed to women's work, linked with intensive effort to sensitize men to the mechanisms of malaria transmission and the principal groups at risk, is seen as a means to increase PIB acquisition and use.

Bedding and Linens↗
PubMed1999

TALL-1 is a novel member of the TNF family that is down-regulated by mitogens.

Members of the tumor necrosis factor (TNF) family play important roles in modulation of immune responses. We describe the identification and cloning of a novel TNF family member that has been designated as TALL-1. TALL-1 is a 285-amino acid type II transmembrane protein. Its carboxy terminus shares approximately 35% sequence identity with the recently identified APRIL and approximately 20-25% with TNF, FasL, TRAIL, and lymphotoxin-alpha, suggesting that TALL-1 and APRIL belong to a subfamily of the TNF family of ligands. Northern blot analysis suggests that TALL-1 is expressed abundantly in peripheral blood leukocytes and weakly in spleen but is barely detectable in all other tissues examined. Reverse transcriptase-polymerase chain reaction analysis indicates that TALL-1 is specifically expressed in monocytes and macrophages but is undetectable in T and B lymphocytes. Furthermore, TALL-1 expression is dramatically down-regulated by phorbol myristate acetate/ionomycin.

Amino Acid Sequence↗
PubMed1999

Gerontological social work and the UN International Year of Older Persons. Interview by Stanley L. Witkin.

To highlight the United Nations International Year of Older Persons and to increase awareness of social work issues related to older people, the editor of Social Work conducted an interview with four distinguished social workers involved in gerontological social work. The interviewees identified professional needs and various policy and practice issues for social work education and practice.

Aged↗
PubMed1998

Alterations in heart failure of cyclic AMP-dependent inotropic and lusitropic properties of cardiac and skeletal muscle.

A central working hypothesis in our laboratory is that deficient cellular cyclic AMP concentrations may be responsible, at least in part, for striated muscle dysfunction, both cardiac and skeletal, in heart failure. These results suggest that therapy aimed at restoring cyclic AMP to normal levels may be effective with regard to improving systolic and diastolic function in the heart and may decrease the development of fatigue in skeletal muscle of patients with failure. The use of cyclic AMP-dependent drugs in clinical practice has been limited by side effects associated with raising total cellular content of this cyclic nucleotide. However, evidence suggesting that separate pools of cyclic AMP may exist within the cell raises the possibility that those pools associated with excitation/contraction coupling could serve as more specific therapeutic targets.

Animals↗
PubMed1998

Obstetric events leading to anal sphincter damage.

OBJECTIVE: To identify the obstetric factors relating to anal sphincter injury at first vaginal delivery by prospective cohort study of primiparous women. METHODS: We compared the results of a bowel function questionnaire and anal vector manometry before and 6 weeks after delivery in 184 primiparous women. Postpartum, pudendal nerve conduction latency was measured in all women, and anal endosonography was performed in 81 with altered fecal continence or abnormal physiology. RESULTS: Sixteen (9%) women, none of whom had altered fecal continence, were delivered by cesarean. After vaginal delivery, 42 of 168 (25%) women had impairment of fecal continence and 76 of 168 (45%) women had abnormal anal physiology. Instrumental vaginal delivery was associated with an 8.1-fold (95% confidence interval [CI] 2.7, 24.0; P < .001) risk of anal sphincter injury and a 7.2-fold (95% CI 2.8, 18.6; P < .001) risk of symptoms. Duration of the second stage of labor beyond 60 minutes led to a 1.7-fold (95% CI 1.14, 2.48; P;< .01) risk of anal sphincter injury and a 1.6-fold (95% CI 1.03, 2.6, P = .01) risk of symptoms. Epidural analgesia, used in 58% of vaginal deliveries, prolonged the second stage of labor (P = .004; odds ratio [OR] 7.7; 95% CI 4.0, 14.7) and was associated with increased risk of sphincter injury (P = .02; OR 2.1; 95% CI 1.1, 4.0) and of symptoms (P = .02; OR 2.0; 95% CI 1.1, 3.7). CONCLUSION: Instrumental delivery and a second stage of labor prolonged by epidural analgesia are the obstetric factors that pose the greatest risk of injury to the anal sphincter mechanism in primiparous vaginal delivery.

Anal Canal↗
PubMed1998

Seroprevalence of Borrelia burgdorferi sensu lato infection in blood donors and park rangers in relation to local habitat.

Serum samples were obtained from blood donors in eleven selected locations in Ireland and tested for antibodies to Borrelia burgdorferi s.l. by enzyme immunoassay (EIA) and immunoblot (IB). The highest seroprevalence (8.7%) was found in Portumna, an area rated as high risk because of the presence of public access woodland harbouring both ticks and spirochaete reservoir hosts. The lowest seroprevalence (0.0%) was found in Ballina, an area where there is no suitable woodland though ticks are common on pastures grazed by cattle and sheep. These results support the findings of an earlier less extensive study and suggest that infection with B. burgdorferi s.l. in Ireland is mainly associated with mixed woodland containing deer and a variety of spirochaete reservoir hosts. The lack of association of tick-infested farmland with seropositive samples suggests that exposure to ticks alone is not a reliable indicator of risk of Lyme borreliosis. This is supported by the fact that none of 38 park rangers, all of whom are regularly bitten by ticks, were seropositive for B. burgdorferi s.l. The low overall seroprevalence of 3.4% in Ireland correlates with the rarity of clinical cases compared with continental European countries, and is due in part to the scarcity of high risk Lyme borreliosis habitat.

Animals↗
PubMed1998

Decreased axosomatic input to motoneurons and astrogliosis in the spinal cord of aged rats.

An increasing body of evidence indicates that aging-related impairments of nervous functions are caused by damage to neuron integrity rather than by loss of neurons. By using electron microscopy, we have examined axosomatic boutons on spinal cord motoneurons derived from aged and young adult Sprague-Dawley rats. The main finding was that about half of the examined motoneuron somata from aged rats had a reduced (50%) bouton coverage, which seemed to be caused by a smaller number of axosomatic bouton profiles. Long stretches of the cell body plasma membrane were apposed by pale processes, and immunolabeling for glial fibrillary acidic protein (GFAP) disclosed that a number of the aged motoneurons appeared embedded in GFAP immunopositive processes. Lumbar motoneurons seemed to be more severely affected than cervical motoneurons. At the ultrastructural level, affected motoneurons disclosed plasma membrane irregularities with appendages/sprout-like extensions that in some cases were sites for axosomatic contacts.

Aging↗
PubMed1998

Incidence of selective serotonin reuptake inhibitor (SSRI) induced hyponatraemia due to the syndrome of inappropriate antidiuretic hormone (SIADH) secretion in the elderly.

OBJECTIVE: The study determines the incidence of SSRI-induced hyponatraemia due to SIADH in an elderly psychiatric inpatient population. DESIGN: A retrospective case-note study. SETTING: An acute old age psychiatry ward. SAMPLE: Patients admitted from January 1 to December 31, 1996. MEASURES: Demographics, medication, psychiatric diagnoses, plasma sodium level and physical comorbidity were collected. Patients on SSRIs were selected and those developing hyponatraemia due to SIADH were identified. RESULTS: Of 32 patients taking SSRIs, four developed symptomatic hyponatraemia due to SIADH (12.5%). A further four developed asymptomatic hyponatraemia following introduction of an SSRI (12.5%), although laboratory confirmation of SIADH was lacking. CONCLUSIONS: The incidence of SSRI-induced hyponatraemia due to SIADH has not previously been established. This study shows a high incidence in elderly patients of this potentially dangerous complication. Clinical practice in the prescription of SSRIs to elderly people must change to include monitoring of electrolytes for early detection and reduction of morbidity.

Acute Disease↗
PubMed1997

Psychiatric manifestations of normal-pressure hydrocephalus: a short review and unusual case.

Normal-pressure hydrocephalus (NPH) is a common cause of potentially reversible dementia. It can present with psychiatric manifestations that may hinder its diagnosis. A 68-year-old man presented with a paranoid psychosis and mild cognitive impairment, but not neurological signs or classic "triad." Gait disturbance and urinary incontinence developed later in the course of illness after the diagnosis of NPH had already been made on computed tomographic (CT) scanning. A lumbo-peritoneal shunt was performed, followed by full remission of psychotic symptoms, as well as considerable improvement in functioning, continence, and gait. This case demonstrates the need to consider NPH when older patients present with psychotic symptoms, particularly in the presence of cognitive impairment, gait disturbance, or incontinence. The decision whether to perform a shunting operation is often difficult, because selection of patients with good prognosis is still inaccurate. CT scanning of the brain is an important investigation in older patients presenting with both functional and organic disorders.

Aged↗
PubMed1997

Anaemia associated with androgen deprivation in patients with prostate cancer receiving combined hormone blockade.

OBJECTIVE: To describe the incidence, time to onset and extent of anaemia occurring in patients with prostate cancer receiving combined hormone blockade (CHB) and the timing and extent of recovery from anaemia in those patients where CHB was discontinued. PATIENTS AND METHODS: Patients with prostate cancer were evaluated prospectively by physical examination and laboratory tests at baseline and at routine intervals while receiving CHB. Of 142 patients who received CHB, 133 were evaluable for the assessment of anaemia; CHB was discontinued in 76 patients, of whom 64 were assessable for recovery from their anaemia. RESULTS: Haemoglobin levels declined significantly in all patients from a mean baseline of 149 g/L to means of 139 g/L, 132 g/L and 131 g/L at 1, 2 and 3 months, respectively. Haemoglobin levels continued to decline during CHB to a mean nadir of 123 g/L at a mean of 5.6 months of CHB, representing a mean absolute haemoglobin decline at nadir of 25.4 g/L. In 120 of the 133 (90%) patients, the relative decline in haemoglobin at nadir was > or = 10% and was > or = 25% in 17 (13%) others, representing a mean absolute haemoglobin decline in this subset of 42.7 g/L. Significant symptoms related to anaemia occurred in 17 patients (13%). Anaemia and symptoms in these patients were easily corrected with the subcutaneous administration of recombinant human erythropoietin. CONCLUSIONS: The anaemia associated with androgen deprivation is significant and occurs routinely in men receiving CHB. It is normochromic, normocytic, temporally-related to the initiation of androgen blockade and usually resolves after CHB is discontinued. We suggest that patients receiving CHB undergo haematological testing at baseline, 1-2 months after initiating CHB and periodically thereafter. Patients developing anaemia should be questioned about symptoms reflecting physiological compromise (e.g. angina, dyspnoea on exertion). In the absence of other causes, CHB should be suspected in the development of anaemia in patients receiving this treatment.

Age Factors↗
PubMed1997

Factors associated with rapid labour in nulliparae.

The objective of this study was to assess the factors which may influence rapid labour in nulliparae. This is a cohort study of 991 consecutive nulliparae who were admitted in spontaneous labour with a singleton pregnancy and cephalic presentation. The setting was the National Maternity Hospital, Dublin where active management of labour is applied to all nulliparae fitting the above criteria. Rapid labour of 2 hours or less occurred in 82 patients (8.3%). Dilatation of 2 cm of the cervix on admission in labour, gestation of less than 37 weeks, and diminishing birthweight, were more common in rapid labours compared with other labours. Women in rapid labour were not surprisingly less likely to require oxytocin augmentation, or to need operative vaginal delivery or Caesarean section, receive epidural anaesthesia, or attend antenatal classes, compared with other women in labour. Rapid labour was not influenced by the finding that the membranes were already ruptured before admission, the time spent at home with contractions, or social background. Women with rapid labour were more likely to arrive in hospital within 4 hours compared with other women in labour. Rapid labour depends on the efficiency of uterine action which is reflected by the dilatation of the cervix on admission.

Journal Article↗