Biomedical subjects
Publications and source records attributed to J Howard.
Six patients undergoing aortic valve replacement had rare or unusual causes of isolated, pure aortic regurgitation. Two patients had congenitally bicuspid aortic valves with a false commissure (raphe) displaced to the aortic wall ("tethered bicuspid aortic valve"), two had floppy aortic valves, one had a congenital quadricuspid valve, and one had radiation-induced valve damage.
Recent developments have taken place in the diagnosis of cardiovascular disorders in the area of cardiac imaging techniques. From a previous era of imaging by silhouettes (chest roentgenography, fluoroscopy, angiocardiography), we have emerged into an era of imaging by tomographic scanning (echocardiography, radionuclide tomography, computed tomography, magnetic resonance). A basic understanding of tomographic cardiac anatomy is the foundation for proper use and interpretation of these new imaging modalities. The present report provides a description of the techniques of tomographic cutting of necropsy cardiac specimens and illustrates some of the pathologic cardiac abnormalities cut in these tomographic planes. Part I of this report describes position of the heart and tomographic axis planes, preparation of the heart and methods of cutting at necropsy, and the short-axis, two-chamber, and four-chamber views of the heart.
Recent developments have enhanced the diagnosis of cardiovascular disorders in the area of cardiac imaging techniques. From an era of imaging by silhouettes (chest roentgenography, fluoroscopy, angiocardiography), we have emerged into an era of imaging by tomographic scanning (echocardiography, radionuclide tomography, computed tomography, magnetic resonance). A basic understanding of tomographic cardiac anatomy is the foundation for proper use and interpretation of these new imaging modalities. The present report provides a description of the techniques of tomographic cutting of necropsy cardiac specimens and illustrates some of the pathologic cardiac abnormalities cut in these tomographic planes. Part II of this report describes the long-axis method, methods using the body rather than the heart as the reference axis, and includes transverse, frontal, and parasagittal methods of imaging the heart.
Electroejaculate traits and circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone concentrations were analyzed in adult leopard cats (Felis bengalensis), a rare felid species indigenous to east Asia. The ability of leopard cat sperm to bind and penetrate zona-free hamster ova and zona-intact domestic cat oocytes in vitro was examined as a means of testing sperm function. The influence of culture media [Biggers, Whitten, Whittingham (BWW) vs. modified Krebs Ringer bicarbonate (mKRB)], seminal plasma removal, and swim-up separation on sperm motility, sperm morphology, and oocyte penetration also were assessed. Sperm treatments included dilution of raw semen (DR), ejaculate centrifugation, and either resuspension (NS) or swim-up processing (SU). The percentage of oocytes penetrated (penetration rate) and the number of penetrated sperm/oocyte (penetration index) were determined. Ejaculates from each male consisted of at least a 50% sperm motility rating, and hormone concentrations in individual males were unrelated to any ejaculate trait measured concurrently on the same day. The SU technique improved (P less than 0.05) percent sperm motility and the proportion of structurally normal sperm compared to DR and NS treatments. Leopard cat spermatozoa were capable of binding to and penetrating hamster ova and domestic cat oocytes; however, penetration was influenced by culture medium and seminal processing. In the hamster assay, a higher (P less than 0.05) penetration rate and penetration index were achieved when mKRB was used for gamete incubation instead of BWW. NS processing also increased (P less than 0.05) overall penetration compared to DR and SU. In the cat oocyte assay, zona penetration rate was similar (P greater than 0.05) in the DR, NS, and SU aliquots; however, the zona penetration index was increased (P less than 0.05) by the NS compared to the DR and SU treatments. This study 1) provides baseline ejaculate and endocrine norms for the leopard cat, 2) demonstrates that leopard cat sperm undergo nuclear decondensation in hamster ova and penetrate zona-intact domestic cat oocytes, 3) indicates that seminal plasma removal enhances leopard cat sperm fertilizing ability and ovum penetration, and 4) suggests that heterologous oocyte penetration is effective for assessing factors influencing fertilization and sperm function in this nondomestic felid.
A sensitive, simple, and quantitative assay for determining neomycin phosphotransferase (NPT) activity in plant cell extracts is described. The procedure retains the simplicity of previously published methods, yet offers up to a 140-fold increase in sensitivity. This increase is due to (1) the addition of bovine serum albumin (BSA) to the assay mixture, (2) desalting of crude maize extracts to remove a low-molecular-weight inhibitor of the enzyme, and (3) use of a different extraction buffer and an improved extraction procedure to liberate more enzyme from the cells. This method has been used successfully to detect and quantitate both stable and transient expression of NPT in transgenic tobacco and maize tissue.
The drug use and related perceptions of 292 young offenders, 94% of those resident in the nine detention centres operated by the New South Wales (NSW) Department of Family and Community Services, were surveyed. The average age of the detainees was 16.3 years and 90.1% were male. Illicit drug use had commenced about 2 years after the use of non-medicinal, but licit substances, and nearly 25% had used drugs from nine or more drug groupings. Alcohol (94.8%), analgesics (94.5%) and nicotine (92.4%) were the drugs most used, with 86.6% having used cannabis, 53.3% stimulants, 48.5% inhalants, 40.5% hallucinogens and 25.8% narcotics. The major reasons given for use were: wanting to feel good, curiosity and boredom. Familial drug use was common and heroin was perceived as the drug most dangerous to both body and mind. The results are discussed and suggestions made regarding appropriate services for adolescents, as most surveyed did not or would not use those which exist.
A miniature osmotic pump has been developed (Osmet) with ALZA, Palo Alto, USA, which can be swallowed, will pass through the stomach and small intestine and then deliver its contents (240 microliters) over eight hours in the large bowel. In vitro studies showed the pumps started to discharge after four to five hours and emptied at a reasonably constant rate of 20.4 microliters/h from 9-16 h (9.6%/h). In vivo studies using gamma-scintigraphy in seven healthy subjects show that the pumps left the fasting stomach at 1.2 h (range 0-3) and arrived in the caecum by 6.4 h (range 5-9). Mean start-up time was 5.3 (0.2) h and the rate of discharge was 15.9 microliters/h for pumps studied from 6-12 h and 17.2 microliters/h for those studied from 10-20 h. This device is simple, safe and effective for the delivery of tracer substances to the caecum and colon without interfering with patients' normal lifestyle.
An epidemiologic study of clinical signs and symptoms of temporomandibular disorders (TMD) was conducted with a probability sample of adults enrolled in a major health maintenance organization (HMO). This report presents data from a first wave field examination and interview conducted by trained, calibrated dental hygienist field examiners. Significant gender differences for vertical jaw opening measures were observed but no significant age differences were found for the distribution of clinically relevant findings. Clinic cases showed smaller amounts of vertical range of jaw motion but did not differ from community cases or controls on extent of lateral, protrusive, or retrusive mandibular movements; on classification of occlusion; or on dentally related variables. Clinic cases had more pain during all jaw excursions as well as during muscle and joint palpation. Joint clicking sounds were also observed more frequently in clinic cases.
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Clinical and epidemiological data support a role for human papilloma virus (HPV) type 16 in the pathogenesis of cervical carcinoma. The W12 cell line contains HPV16 sequences, predominantly as a high copy number episome, and is immortalised in vitro, but non-tumourigenic. A morphologically distinct sub-line of the parental W12 cell line was isolated which displayed increased growth rate, increased capacity for self-renewal and increased resistance to differentiation in comparison with the parental W12 cell line. The structure and expression of the HPV16 sequences was virtually identical in the two cell lines. However, expression of the c-myc proto-oncogene was elevated in the morphologically distinct sub-line, and this was associated with amplification, but not rearrangement, of the c-myc locus. Karyotype analysis demonstrated that amplification of the c-myc locus was a result of duplication of the long arm of chromosome eight.
Project T.E.A.M.S. (Training, Education, and Management Skills: Meeting the Needs of Infants Prenatally Exposed to Drugs), funded by a training grant from the National Center on Child Abuse and Neglect, developed skilled interdisciplinary teams to support caregivers and optimize the health and environmental care of infants exposed prenatally to drugs and placed in out-of-home care. Using both didactic and clinical approaches, the 6-month program addressed the medical, developmental, environmental, and physical care needs of drug-exposed infants and toddlers; the special needs of their caregivers; and family dynamics and parenting issues. By enhancing the knowledge and skills of staff from community-based child welfare and health care agencies, this project demonstrated a training approach for enhancing the skills of professionals who serve the growing population of prenatally drug-exposed infants.
Kinesin is a motor protein that uses energy derived from ATP hydrolysis to move organelles along microtubules. Using a new technique for measuring the movement produced in vitro by individual kinesin molecules, it is shown that a single kinesin molecule can move a microtubule for several micrometers. New information about the mechanism of force generation by kinesin is presented.
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Discrimination of the M, Z, and S alleles of alpha 1-antritrypsin (AAT) has been carried out using in vitro gene amplification with the polymerase chain reaction (PCR). Amplification of 90 nucleotides surrounding the Z mutation site and 120 nucleotides surrounding the S mutation site dramatically improves the sensitivity and reliability of allele-specific oligonucleotide (ASO) hybridization for direct detection of these alleles. Analysis is performed using Southern blots or dot blots hybridized with 19 base oligonucleotides and differentially washed for allele specificity. Amplification of the Z and S mutation sites can be combined in one PCR to allow detection of both mutations when analysed by gel electrophoresis and Southern transfer. This technique can be performed reliably using less than 0.1 micrograms of genomic DNA or less than 100 amniocytes or white blood cells. This technique has been used to perform prenatal diagnosis on a chorionic villus sample (CVS) in a fetus at risk for the ZZ Pi type form of AAT deficiency.
Weakness in haemodialysis patients has been attributed to several factors including carnitine deficiency. Malnutrition, neuropathy, uraemic myopathy and parathyroid hormone excess may all be important. Six haemodialysis patients were shown to have reduced muscle power compared with a normal population, and to be malnourished by dietary assessment, and features of their weakness were investigated. Total carnitine was normal in plasma but elevated in muscle, with an excess of esterified carnitine in both plasma and muscle and diminished free plasma carnitine. Muscle biopsy showed no features of carnitine deficiency and electromyography showed a non-specific neuropathy with additional myopathic changes in some. Dietary supplementation with L-carnitine (2 g/day) for 6 weeks in a placebo-controlled trial showed a redistribution of carnitine fractions but no subjective or objective improvement in muscle function. There was no improvement in the plasma lipid profile. The weakness of haemodialysis patients is multifactorial. We have not demonstrated total carnitine depletion in either muscle or plasma, and oral supplementation of L-carnitine has no demonstrable effect in this group.
The nitrodiphenyl ether herbicide 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitroacetophenone oxime-o-(acetic acid, methyl ester) (DPEI) induces light- and O(2)-dependent lipid peroxidation and chlorophyll (Chl) bleaching in the green alga Scenedesmus obliquus. Under conditions of O(2)-limitation, these effects are diminished by prometyne and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), both inhibitors of photosynthetic electron transport. Mutants in which photosynthetic electron transport is blocked are also resistant to DPEI under conditions of O(2)-limitation. Light- and O(2)-dependent lipid peroxidation and Chl bleaching are also induced by 5-[2-chloro-4-(trifluoromethyl)phenoxy]-3-methoxyphthalide (DPEII), a diphenyl ether whose redox properties preclude reduction by photosystem I. However, these effects of DPEII are also inhibited by DCMU. Under conditions of high aeration, DCMU does not protect Scenedesmus cells from Chl bleaching induced by DPEI, but does protect against paraquat. DPEI, but not paraquat, induces tetrapyrrole formation in treated cells in the dark. This is also observed in a mutant lacking photosystem I but is suppressed under conditions likely to lead to O(2) limitation. Our results indicate that, in contrast to paraquat, the role of photosynthetic electron transport in diphenyl ether toxicity in Scenedesmus is not to reduce the herbicide to a radical species which initiates lipid peroxidation. Its role is probably to maintain a sufficiently high O(2) concentration, through water-splitting, in the algal suspension.
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