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Biomedical subjects

J Howe

Publications and source records attributed to J Howe.

At least 55 records · Page 3Linked to original sources
PubMed1995

Comparison of 1.5 Tesla and 0.35 Tesla field strength magnetic resonance imaging scans in the morphometric evaluation of the lumbar intervertebral foramina.

OBJECTIVE: To compare magnetic resonance imaging (MRI) scans obtained from 1.5 Tesla (T) MRI units with scans obtained from 0.35T MRI units in the morphometric evaluation of the lumbar intervertebral foramina (IVF). DESIGN: Three dimensions of lumbar IVFs were measured on a cadaveric lumbar spine by using Vernier calipers. The spine was embedded in gelatin to simulate soft tissue and scanned twice in a 1.5T MRI unit (3-mm and 5-mm slice thicknesses) and once in a 0.35T MRI unit (5-mm slice thickness). Measurements from the scans were made independently by three observers. The results obtained from the two units were compared to the actual IVF size (as measured by calipers) and to one another. RESULTS: The greatest superior-to-inferior distance had the strongest statistically significant correlation to the actual cadaver measurements for both the 0.35T and 1.5T imaging units [r = 0.986 (0.35T); r = 0.985 (1.5T at 3 mm) and r = 0.981 (1.5T at 5 mm); p < .0001 in all cases]. Mean differences and standard errors were minimal between measurements made from MRI scans of both 1.5T and 0.35T units and measurements made directly from the cadaveric spine. CONCLUSION: Both imaging units produced images that accurately depicted the actual size of the IVF. The MRI units of 0.35T field strength produced images of high morphometric accuracy. In addition, the potential for side effects and the operating costs are less with 0.35T units. Therefore, 0.35T MRI units may be a prudent choice as a clinical and research imaging tool in the evaluation of the lumbar IVF.

Humans↗
PubMed1994

A multiple fission-like mode of asexual reproduction in Blastocystis hominis.

A non-axenic and an axenic isolate of Blastocystis hominis have been induced to form cysts in vitro using an encystation medium. The morphology of the parasite at different time points was observed by scanning electron microscopy. In day-2 cultures the cysts were spherical and had a non-uniform, coarse outer surface around the body. A deep, pore-like opening was seen in some of the parasites. Most of the cysts from day-4 and day-6 cultures ruptured, revealing small, uniformly sized spherical bodies occurring in grape-like clusters. Acridine orange staining confirmed that these bodies were the progeny of Blastocystis hominis. A multiple fission-like reproduction process giving rise to many daughter Blastocystis occurs within the cyst.

Acridine Orange↗
PubMed1994

Flavivirus West Nile (Sarafend) egress at the plasma membrane.

West Nile (Sarafend) virus was distinctly observed to bud from the plasma membrane rather than mature intracellularly. This has been observed with transmission electron microscopy. Using conventional scanning electron microscopy, budding at the plasma membrane especially at the filopodia was clearly illustrated. Immunogold labelling against the virus envelope protein was also performed to confirm this mode of exit. The gold particles were observed to be located at the sites where virus budding was seen under the field emission scanning electron microscope.

Animals↗
PubMed1994

Ultrastructural changes during in vitro encystment of Blastocystis hominis.

The morphological changes occurring in Blastocystis hominis at different time points following in vitro encystment were studied by electron microscopy. The following stages of the parasite were sequentially seen: (a) the amoebic form, which was irregular in shape, with a majority of the organelles being concentrated at the condensed cytoplasmic region; (b) the pre-cystic form, which was rounded and had an electron-dense material forming a homogeneous wall around the central body; and (c) the cystic form, which had a very prominent, thick osmiophilic electron-dense wall, within which there were many inclusions and possibly reproductive granules. The amoebic form appeared to be an intermediate stage between the vacuolar form and the pre-cystic form, as this stage allowed the parasite to ingest bacteria to enhance encystment. The pre-cystic stage had previously been shown in experimental infection to be infective. The role of the cystic stage in producing infection is currently being investigated.

Animals↗
PubMed1994

The treatment of sicca features in Sjögren's syndrome: a clinical review.

Patients with SS often suffer considerable distress due to sicca symptoms and the complications of mucosal dryness. Although there are many topical treatments available, the literature on their use is scant. This paper describes the treatments available and suggests a rationale for the choice of product.

Humans↗
PubMed1994

Facilitating parenting skills in vulnerable families.

Parents regularly seek advice from their health visitor about how to cope with their child's difficult behaviour. Often the health visitor feels she has nothing constructive to offer, writes Norma Angeli et al. Here they describe how one team of health visitors introduced the STEP positive parenting programme, devised in the US, successfully to help parents from all cultures, classes and backgrounds achieve a better relationship with their child.

Adaptation, Psychological↗
PubMed1993

Alternating fluency in Parkinson's disease. An evaluation of the attentional control theory of cognitive impairment.

One theory for the pattern of cognitive impairment associated with Parkinson's disease is that deficits are apparent only on tasks which rely on the internal control of attention, which in turn is assumed to place heavy demands on limited attentional resources. This theory is evaluated in the present study by examining the performance of Parkinson's disease subjects and matched healthy control subjects on a series of fluency tasks. In one condition, subjects were required to generate exemplars under standard verbal fluency instructions, i.e. either to a single letter or a single semantic category. In a related condition, subjects had to generate exemplars alternately using two fluency probes, which could either be from the same domain, i.e. letter-letter or category-category, or from different domains, i.e. category-letter. The requirement to alternate between fluency probes presumably places greater demands on internal attentional control mechanisms, and in a yoked condition, subjects were given external cue cards to minimize these extra demands. Overall, there was no evidence that Parkinson's disease subjects had a basic fluency deficit, nor were they impaired when required to alternate between probes of the same domain. A specific deficit did emerge, however, for the mixed alternating condition (i.e. category-letter), in which Parkinson's disease subjects produced significantly more perseverative errors and had a significantly lower output. The former of these was reversible by the provision of external cue cards, but the overall output was unchanged. These data do not support the theory of internal attentional control, at least as a general theory of cognitive impairment in Parkinson's disease. To explain the observed pattern, we propose that Parkinson's disease is associated with: (i) a deficit in inhibitory attentional processes, and (ii) an impairment in the maintenance of those internal representations which control action.

Aged↗
PubMed1993

The effects of indomethacin and naproxen on zidovudine pharmacokinetics.

The effects of indomethacin and naproxen on zidovudine (ZDV) pharmacokinetics were studied in six patients with the acquired immunodeficiency syndrome (AIDS), AIDS related complex (ARC) or asymptomatic HIV disease using a placebo-controlled crossover design. Indomethacin 25 mg twice daily or naproxen 250 mg twice daily did not alter ZDV pharmacokinetics compared with placebo. The mean AUC value for the glucuronidated metabolite, GZDV, was reduced from 26.6 +/- 11.7 mumol l-1 h in the presence of placebo to 20.9 +/- 8.3 mumol l-1 h (95% C.I. of the difference 1.39-9.98; P < 0.05) following treatment with naproxen 250 mg twice daily for 3 days. The small decrease in plasma GZDV in the naproxen phase reflects an increase in clearance of ZDV to other metabolites and/or a decrease in the formation clearance to GZDV and/or an increase in the clearance of GZDV. A decrease in formation clearance to GZDV would be consistent with the results of in vitro studies reported previously. No significant increase in ZDV concentration in the presence of naproxen may reflect a lower sensitivity of parent drug measurements to selective inhibition of parallel pathways of metabolism. The clinical significance of these findings is unknown but toxicity may be increased if a decreased formation of GZDV is accompanied by shunting of metabolism to 3'-amino-3'-deoxythymidine which is alleged to be cytotoxic.

Acquired Immunodeficiency Syndrome↗
PubMed1993

The Family Practice Residency in Baton Rouge: practice patterns of graduates.

One hundred twenty-four physicians have completed the Baton Rouge Family Practice Residency since 1973. Eighty-two percent of the graduates who are currently active physicians are practicing medicine in Louisiana. Most are practicing family medicine. The graduates were sent questionnaires asking about practice characteristics, office procedures performed, hospital privileges held, and career satisfaction. Responses were received from 74 family physicians serving small, medium, and large communities. Most reported they are satisfied with their career choices. The respondents perform a variety of procedures in their offices. This finding was not affected by community size. Hospital privileges were affected by community size. The residency is meeting its principal mission: (1) training family practitioners for Louisiana, and (2) training doctors to practice in any sized community.

Certification↗
PubMed1992

Effect of tension and placement of a prosthetic anterior cruciate ligament on the anteroposterior laxity of the knee.

We wished to determine the optimal tension required to restore normal joint laxity to anterior cruciate ligament (ACL)-deficient knees using a braided polyethylene ACL prosthesis (PACL). In 10 cadaveric specimens, we measured the anteroposterior (AP) laxity of the intact knee at 10 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion. The ACL was then removed and replaced with the PACL using tunnel-tunnel (T-T) and "over-the-top" (OTT) placement techniques. In both positions, the PACL was initially tensioned to 0, 9, 18, and 27 N with the knee flexed to 30 degrees. AP joint laxity was then measured at each flexion angle. With an increase in initial tension, there was a corresponding decrease in AP laxity. At 30 degrees and 90 degrees of flexion, AP laxity was not significantly different from normal using T-T placement and an initial tension of 0 N. At 90 degrees of flexion, AP laxity was not significantly different from normal using OTT placement at 0 or 9 N of initial tension. For both positions, all other tension levels and flexion angles constrained AP laxity. No laxity differences were detected between the OTT and T-T positions at any flexion angle. The variability in AP laxity of the T-T position was significantly greater than OTT. With a 150-N anterior shear force applied to the proximal tibia, the maximum tensions developed in the PACL were not significantly different between the two positions except at 90 degrees. The results suggest that implantation of the PACL is best performed using OTT positioning with an initial tension of 0 N applied at 30 degrees of knee flexion.

Adult↗
PubMed1992

Research resources.

Explore the source record for details and available documents.

Community Mental Health Services↗
PubMed1991

A Blastocystis species from the sea-snake, Lapemis hardwickii (Serpentes: Hydrophiidae).

Observations were made on Blastocystis isolated from the sea-snake, Lapemis hardwickii. Exponential growth of the organism was observed between 2 and 4 days of culture. Vacuolated, amoeboid and granular forms were observed in cultures, similar to B. hominis. The optimal growth temperature for the sea-snake Blastocystis was 24 degrees C compared with 37 degrees C for B. hominis. The karyotypic patterns of B. hominis and the sea-snake Blastocystis were studied in the clamped homogeneous electric field (CHEF) technique and found to be different. Based on the above differences, the sea-snake Blastocystis was designated as Blastocystis lapemi sp. nov.

Animals↗
PubMed1991

Primary Sjögren's syndrome in north east England--a longitudinal study.

We have documented the initial clinical features of 100 patients with primary Sjögren's syndrome (SS) together with the results of their baseline investigations. The evolution of the disease in these patients has been followed for a median of 34 months (range 3-84 months). The majority of patients were females aged 40-60 years, and common clinical features included eye symptoms (100%), xerostomia (100%), polyarthralgia (94%), Raynaud's phenomenon (81%) and salivary gland swelling (47%). Thyroid disease was relatively common (14%) while other endocrine disease was rare. Four patients died during follow-up, and three cases of lymphoma were detected. Other serious complications included pericarditis (10%), pleuroparenchymal lung disease (9%), renal tubular acidosis (3%) and cerebrovascular accidents (2%). The presence of anti-Ro antibodies identifies patients with more severe systemic disease. Spontaneous improvement occurred in 12 patients, while steroids were required for specific complications in 18. Overall, although lymphoma was found to excess in our group, the high mortality reported with primary SS elsewhere was not seen.

Adolescent↗
PubMed1991

On the putative mechanism of induction and regulation of melanogenesis by L-tyrosine.

The stimulation of melanogenesis by L-tyrosine in hamster melanoma is several-fold higher than that by norepinephrine, epinephrine, clonidine and isoproterenol and absent in the case of tyramine dopamine and phenylephrine. Therefore, the melanogenic effect of L-tyrosine in hamster melanoma follows a different pathway than that linked to the activation of dopaminergic and adrenergic receptors.

Animals↗
PubMed1990

The tymobox, a sequence shared by most tymoviruses: its use in molecular studies of tymoviruses.

The 5'-terminal sequences of the virion protein mRNAs of ononis yellow mosaic and kennedya yellow mosaic tymoviruses were determined, and also the positions in the genomes of the transcription initiation sites of those mRNAs. Comparisons of the available genomic sequences of tymoviruses revealed two conserved regions, one at the initiation site and another longer sequence of sixteen nucleotides to the 5' side of it. The longer sequence, which we call the tymobox, was tested as a target for a designed ribozyme, which cleaved appropriate genomic fragments of three tymoviruses. A synthetic oligonucleotide with sequence complementary to the tymobox was shown to be a tymovirus-specific probe for diagnosing and identifying tymoviruses, except for wild cucumber mosaic tymovirus. The tymobox sequence was also used as a primer for the second strand DNA synthesis of dsDNA representing the virion protein gene of cacao yellow mosaic tymovirus, a tymovirus with unknown sequence. Thus, the tymobox is a useful tool in molecular studies of tymoviruses.

Base Sequence↗