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Biomedical subjects

J Howard

Publications and source records attributed to J Howard.

At least 91 records · Page 5Linked to original sources
PubMed1997

Placement with substance-abusing mothers vs. placement with other relatives: infant outcomes.

Evaluating a subset of participants from a larger research project concerning comprehensive drug treatment services for pregnant substance-abusing women and their offspring, this investigation compared those mothers who retained custody of their infants following delivery with those who lost custody and whose infants were placed in the care of other relatives. There were no differences between the groups with respect to maternal demographics, substance abuse (as assessed by self-report prenatally and urine toxicology screens at birth), or mental health status, or with respect to newborn characteristics (including gestational age, birthweight, medical risk status). Further, caregiving behaviors of mothers and relative caregivers showed no significant differences at 6 months. Infants who remained in the care of their biological mothers, however, demonstrated better cognitive development than infants in the care of relatives at 6 months. There was also a discrepancy in terms of safety at 6 months, in that there were three deaths and two reported cases of suspected child abuse/neglect among infants in the care of their mothers, and no deaths and no reports of suspected abuse among infants in relative foster care.

Adult↗
PubMed1997

Suicide with an air rifle.

We report the case of a 14-year-old boy who committed suicide with the use of an air rifle. We include a brief description of his clinical presentation and course, as well as radiography and autopsy findings. This case represents an uncommon mechanism of suicide with an instrument commonly possessed by adolescents and demonstrates the potential lethality of air rifles. Today's air rifles employ one of three gas-compression systems: pneumatic, spring-air or gas compression. They are capable of generating velocities between 200 and 770 feet/second, enabling pellets or BBs to penetrate skin, soft tissue, and bone. This case also highlights the need for preventive measures, including public education and legislation.

Adolescent↗
PubMed1997

Risky drug practices and treatment needs of youth detained in New South Wales Juvenile Justice Centres.

Demographic, drug use and criminal correlates of risky drug practices were examined among 279 detained youth in NSW Juvenile Justice Centres. Binge drinking was common, with 63% reporting the consumption of at least five drinks in a row in the 2 weeks prior to incarceration. It was associated with being older, being from an English-speaking background, regular tobacco consumption and having a current drug problem. A quarter (24%) of the sample had injected an illicit drug, over one-third (37%) of whom also reported sharing needles. Injectors were more likely to be polydrug users, regular amphetamine users and have a past history of drug treatment. While 16% of the sample indicated a need for drug treatment, only 10% were currently receiving some form of treatment, most commonly counselling. Appropriate strategies are needed among this population to address gaps in treatment provision.

Journal Article↗
PubMed1997

The retirement adjustment process: changes in the well-being of male retirees across time.

The purpose of this prospective study was to (1) evaluate the impact of retirement, (2) monitor the change in adjustment across time, and (3) identify the resources predictive of short- and long-term adjustment in retirement. A sample of 117 male retirees was assessed on indices of physical and psychological health, perceived control, retirement satisfaction, and life satisfaction at 2-4 months preretirement, 1 year post-, and 6-7 years postretirement. The results provided support for a positive impact of retirement, as retirees evidenced increases in well-being during the first year. There was also evidence of a retirement adjustment process, in that aspects of well-being (i.e., psychological health) changed from short- to long-term retirement. Finally, physical health, income, and voluntary retirement status predicted short-term adjustment, while internal locus of control was an additional resource for long-term adjustment. Changes in resources over time also differentially predicted short- and long-term adjustment (e.g., an increase in internal locus of control predicted an increase in activity satisfaction at 1 year but not at 6-7 years postretirement).

Aged↗
PubMed1997

Incidence of non-fatal workplace assault injuries determined from employer's reports in California.

Although fatal work-related assault assault injury rates are routinely reported in the United States, reports of non-fatal injuries are not routinely examined. Non-fatal workplace assault injuries can be reported through many agencies. One of the most common reporting mechanisms in California is the Employer's Report of Occupational Illness and Injury. Employer's Reports filed from October 1, 1994 through January 31, 1995 in the state of California were the source of workplace assault information for this study. All reports indicating an assault-related injury were identified and characterized by gender and occupation of the victim, type of assault and weapon used, and industry. Annual rates were determined based on the number of estimated annual reports and the civilian working population. The estimated annual rate of workplace assault injuries for California based on Employer's Reports is 72.9 per 100,000 workers, which is approximately 50 times the fatal rate. Rates differed by industry, with retail, hospital, transportation and police workers exhibiting the highest rates. Assaults were predominantly Type I, which involve criminal activity, and Type II, which involve an assault by a client, patient, or inmate. The rates of non-fatal work-related assault injury are much greater and have different characteristics than fatal injuries. These non-fatal injury patterns need to be considered when estimating the burden of assault injuries on businesses, and can help identify the most effective prevention strategies.

Absenteeism↗
PubMed1997

Th1 epitope repertoire on the alpha subunit of human muscle acetylcholine receptor in myasthenia gravis.

In myasthenia gravis (MG), CD4+ T helper cells recognize the muscle acetylcholine receptor (AChR) alpha subunit. We investigated the epitope repertoire of anti-AChR blood CD4+ Th1 cells from 13 myasthenic patients and three healthy controls, using overlapping synthetic peptides screening the alpha subunit sequence and an enzyme-linked immunospot (ELISPOT) assay that detects antigen-induced interferon-gamma secretion of individual Th1 cells. All patients recognized a pool of the alpha subunit peptides. All but one patient recognized numerous peptides. Each patient had an individual pattern of peptide recognition, but most or all patients recognized four sequences (residues 48-67, 101-137, 304-322, and 403-437) that stimulated relatively large numbers of Th1 cells. They include previously identified "immunodominant" sequences recognized by AChR-specific CD4+ T cell lines from myasthenic patients. Peptide 1-14 was also recognized frequently. The controls recognized, with a low precursor frequency, the peptide pool and a few peptides that frequently included the immunodominant sequences described above. The present results demonstrate that Th1 cells are involved in the anti-AChR response in MG and that their epitope repertoire is very complex. This indicates that when MG is clinically evident, the AChR itself is the sensitizing antigen and the target of the autoimmune Th1 cells, although it does not exclude that molecular mimicry between one AChR epitope and a microbial structure may have triggered this autoimmune response. Although the complexity of the Th1 repertoire suggests that development of specific immunosuppressive treatments targeted on epitopes recognized by autoimmune T cells will be difficult, the existence of immunodominant T epitope sequences might facilitate that task.

Adolescent↗
PubMed1997

Expression of the alpha 7 subunit of the nicotinic acetylcholine receptor in normal and myasthenic human thymuses.

The nicotinic acetylcholine receptor (AChR) is a transmembrane glycoprotein composed of five homologous subunits. Different isoforms of the AChR alpha subunit exist (alpha 1 to alpha 9). Of them, alpha 1 is expressed in muscle, alpha 2 to alpha 9 in neuronal cells. Muscle AChR is the target autoantigen in the autoimmune disease myasthenia gravis (MG). The thymus is implicated in MG pathogenesis, and the anti-AChR autoimmune response may start in this tissue, that expresses the muscle-type alpha 1 subunit as well as other muscle AChR subunits. The thymus also expresses the "neuronal" alpha 3 and alpha 5 subunits. By using polymerase chain reaction and other molecular techniques, we demonstrate here expression of the AChR alpha 7 subunit transcript in thymuses from both myasthenic patients and normal subjects. The alpha 7 subunit can form homo-oligomeric functional AChR complexes that, like muscle AChR, bind alpha-bungarotoxin. The demonstration of expression of the alpha 7 subunit in the thymus suggests that alpha-bungarotoxin binding, functional AChRs of the neuronal type are normally present in the thymus.

Adolescent↗
PubMed1996

Directional loading of the kinesin motor molecule as it buckles a microtubule.

Single kinesin motor molecules were observed to buckle the microtubules along which they moved in a modified in vitro gliding assay. In this assay a central portion of the microtubule was clamped to the glass substrate via biotin-streptavidin bonds, while the plus end of the microtubule was free to interact with motors adsorbed at low density to the substrate. A statistical analysis of the length of microtubules buckled by single motors showed a decreasing probability of buckling for loads greater than 4-6 pN parallel to the filament. This is consistent with kinesin stalling forces found in other experiments. A detailed analysis of some buckling events allowed us to estimate both the magnitude and direction of the loading force as it developed a perpendicular component tending to pull the motor away from the microtubule. We also estimated the motor speed as a function of this changing vector force. The kinesin motors consistently reached unexpectedly high speeds as the force became nonparallel to the direction of motor movement. Our results suggest that a perpendicular component of load does not hinder the kinesin motor, but on the contrary causes the motor to move faster against a given parallel load. Because the perpendicular force component speeds up the motor but does no net work, perpendicular force acts as a mechanical catalyst for the reaction. A simple explanation is that there is a spatial motion of the kinesin molecule during its cycle that is rate-limiting under load; mechanical catalysis results if this motion is oriented away from the surface of the microtubule.

Animals↗
PubMed1996

Bloodstream infections in home infusion patients: the influence of race and needleless intravascular access devices.

OBJECTIVES: To determine the cause of increased central venous catheter-associated (CVC) bloodstream infection (BSI) rates in a cohort of pediatric hematology /oncology patients receiving home health care (HHC). METHODS: A retrospective cohort study of hematology/oncology patients with CVCs receiving HHC from January 1992 through November 1994. RESULTS: Of 182 patients with CVCs identified during the study period, 58 (32%) acquired 90 BSIs during 75,085 CVC days. BSI rates increased significantly from 1992 through 1994 (0.8 vs 1.0 vs 1.7 BSIs per 1000 CVC days; p < 0.005). Known risk factors, including catheter type, patient age less than 5 years, sex, or diagnosis, were not associated with increased BSI rates. After introduction of needleless devices for CVC access to the HHC regimen in May 1993, BSI rates increased 80% (from 0.81 to 1.46 BSIs/1000 CVC days, relative risk 1.8; p < 0.02). The only other significant risk factor was the race of the patient. White children had the lowest BSI rate before and after needleless-device introduction (0.4 vs 0.9 BSIs/1000 CVC days; p > 0.1), whereas black patients had the highest, unaffected by the introduction of these devices (2.5 BSIs/1000 CVC days). Both Hispanic (0.5 vs 1.6 BSIs/1000 CVC days) and Asian-American children's (0.4 vs 1.5 BSIs/1000 CVC days) BSI rates increased threefold and fourfold after the introduction of needleless devices. CONCLUSIONS: Our data suggest that pediatric hematology/oncology patients receiving HHC via needleless devices may have an increased risk of BSIs, and this risk may vary by race. We hypothesize that prevention of BSIs may require consideration of cultural, ethnic, and language differences when parents are trained to provide care for their children with CVCs in the home.

Adolescent↗
PubMed1996

"Non injectables": methadone syrup and benzodiazepine injection by methadone-maintained clients.

To obtain more information about anecdotal reports of injection of methadone syrup and benzodiazepine drugs among injecting drug users, interviews were conducted with 32 subjects as part of a larger study into drug use patterns of clients in methadone maintenance treatment. Subjects were asked about frequency of injection of methadone and benzodiazepines, reasons for injection and methods of preparation for injection. The study found that 78% had injected methadone and 25% had injected benzodiazepines at some time during their drug using careers. Service providers can play an important role in promoting harm minimization strategies, and utilizing behaviour modification techniques.

Journal Article↗
PubMed1996

Sperm capacitation and the acrosome reaction are compromised in teratospermic domestic cats.

The efficiency of sperm capacitation and of the acrosome reaction was studied in the teratospermic domestic cat to evaluate further the etiology of compromised zona pellucida penetration and oocyte fertilization. Specific objectives were to compare normospermic and teratospermic cat ejaculates for 1) the kinetics and timing of sperm capacitation in vitro as determined by an ionophore-induced acrosome reaction; 2) the incidence of spontaneous acrosomal loss; 3) the ability of capacitated, swim-up processed sperm to acrosome-react in response to chemical (calcium ionophore) or physiological (solubilized zonae pellucidae) inducers; and 4) differences in acrosomal ultrastructure by use of transmission electron microscopy (TEM). Acrosomal status was determined with the fluorescent probe Arachis hypogaea (peanut) agglutinin. The timing of in vitro capacitation differed (p < 0.05) between cat populations. Normospermic samples were capacitated at 2.0 h postcentrifugation, whereas teratospermic samples required 2.5 h to become capacitated. At 2.5 h, sperm from teratospermic males were less capable (p < 0.05) of completing the acrosome reaction after ionophore exposure (49.3 +/- 8.0%) than sperm from normospermic males (73.3 +/- 3.8%). Levels of spontaneous acrosomal loss/reaction over time were similar (p > 0.05) between cat groups (range, 7.6-17.8%). In swim-up separated sperm from normospermic cats, ionophore A23187 was a more potent inducer (p < 0.05) of the acrosome reaction (70.1 +/- 6.5%) than solubilized zonae pellucidae (31.1 +/- 1.2%). Swim-up separated sperm from teratospermic cats, however, were compromised in the ability to acrosome react, regardless of inducer (ionophore, 23.9 +/- 3.3%; solubilized zonae pellucidae, 23.9 +/- 4.7%; p > 0.05). Sperm motility patterns over time indicated that differences in acrosomal status were not influenced by cell death. The frequency of abnormal acrosomes detected by TEM was higher (p < 0.05) in teratospermic (30.0 +/- 3.9%) than in normospermic (3.1 +/- 1.3%) samples. Swim-up separation failed to reduce (p > 0.05) the proportion of sperm cells with malformed acrosomes (swim-up, 33.5 +/- 3.5%; washed, 26.6 +/- 4.6%). These results indicate that sperm from teratospermic cats exhibit a high incidence of malformed acrosomes detectable only at the ultrastructural level. Nevertheless, acrosomal dysfunction is not related exclusively to structural defects because > 40.0% of swim-up separated sperm with structurally normal acrosomes still are incapable of completing the acrosome reaction. This suggests that compromised capacitation and acrosomal dysfunction may be responsible for low fertilization success in the teratospermic domestic cat.

Acrosome↗