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Biomedical subjects

B Willis

Publications and source records attributed to B Willis.

At least 19 recordsLinked to original sources

Bromocriptine use is associated with decreased smoking rates.

Dopaminergic transmission in the central nervous system is thought to underlie addictive behaviours, including smoking. One effective smoking cessation drug, bupropion, enhances dopaminergic transmission; conversely, antipsychotic drugs, which are dopamine antagonists, are associated with increased smoking. Thus we hypothesized that subfertile women treated with the potent dopamine agonist bromocriptine might smoke less as a consequence of their treatment. Among 4,608 subfertile women those conceiving on bromocriptine were half as likely to smoke as those taking other drugs or those conceiving without medication (p < 0.0001). This observation supports the role of dopamine in nicotine addiction, and suggests that bromocriptine-like drugs could be used effectively by pregnant women to aid cessation.

Bromocriptine↗

Aminoglycoside-nucleic acid interactions: remarkable stabilization of DNA and RNA triple helices by neomycin.

The stabilization of poly(dA).2poly(dT) triplex, a 22-base DNA triplex, and poly(rA).2poly(rU) triple helix by neomycin is reported. The melting temperatures, the association and dissociation kinetic parameters, and activation energies (E(on) and E(off)) for the poly(dA).2poly(dT) triplex in the presence of aminoglycosides and other triplex binding ligands were determined by UV thermal analysis. Our results indicate that: (i) neomycin stabilizes DNA triple helices, and the double helical structures composed of poly(dA).poly(dT) are virtually unaffected. (ii) Neomycin is the most active and triplex-selective stabilization agent among all aminoglycosides, previously studied minor groove binders, and polycations. Its selectivity (DeltaT(m3-->2) vs DeltaT(m2)(-->)(1)) exceeds most intercalating drugs that bind to triple helices. (iii) Neomycin selectively stabilizes DeltaT(m3)(-->)(2) for a mixed 22-base DNA triplex containing C and T bases in the pyrimidine strand. (iv) The rate constants of formation of triplex (k(on)) are significantly enhanced upon increasing molar ratios of neomycin, making triplex association rates closer to duplex association rates. (v) E(on) values become more negative upon increasing concentration of aminoglycosides (paromomycin and neomycin). E(off) values do not show any change for most aminoglycosides except neomycin. (vi) Aminoglycosides can effectively stabilize RNA [poly(rA).2poly(rU)] triplex, with neomycin[being one of the most active ligands discovered to date (second only to ellipticine). (vii) The stabilization effect of aminoglycosides on triple helices is parallel to their toxic behavior, suggesting a possible role of intramolecular triple helix (H-DNA) stabilization by the aminoglycosides.

Aminoglycosides↗

Pathological evaluation of intervertebral disc tissue specimens after routine cervical and lumbar decompression. A cost-benefit analysis retrospective study.

BACKGROUND: After decompression of cervical and lumbar nerve roots for radicular pain, pathological evaluation of the extracted disc material is commonly performed. Although histological examination rarely detects clinically significant unsuspected disease, it remains a common practice in most hospitals in the United States. To determine the cost-effectiveness of this routine practice, we conducted a retrospective study. The results are contained within this report. METHODS: Using the University Neurosurgery database, we retrospectively identified 1,387 patients who had spinal decompression surgery (laminectomy and/or discectomy). These cases were broadly classified into routine and non-routine cases depending on the preoperative diagnosis. Benign and noninfectious cases were classified as routine; malignant and all other cases were classified as nonroutine. We reviewed the medical records and pathology reports of these routine and nonroutine cases in an attempt to study the efficacy of the pathological evaluation of the disc material. The cost-benefit value of histopathology in these cases was analyzed, retrospectively. RESULTS: In all routine cases, the histopathology was consistent with benign disc disease and yielded no additional information that could have altered the treatment plan. In the nonroutine cases, however, histopathology was significant in the management of the patient. The cost factor for pathological study was the same for both case groups. CONCLUSIONS: Pathological study of intervertebral disc specimens is cost beneficial only in cases with significant preoperative clinical diagnoses. Pathological evaluation of routine herniated nucleus pulposus extracted during decompressive surgeries is not warranted.

Cervical Vertebrae↗

Burr-hole versus twist-drill drainage for the evacuation of chronic subdural haematoma: a comparison of clinical results.

BACKGROUND: Most neurosurgeons remove clinically symptomatic subdural haematomata, but the techniques they choose remain controversial. METHOD: The results from sixty-two patients diagnosed with chronic subdural haematoma were evaluated for technique, postoperative computerized tomography (CT) scan results, and complications. RESULTS: Eleven patients had haematomata evacuated using twist-drill plus drain, 37 patients had haematomata evacuated with burr-hole only, and 14 patients were evacuated with burr-hole plus drain. Of the patients who underwent twist-drill and closed system drainage (CSD), 43% had smaller lesions on CT follow-up scans, as compared with 74% of those who underwent the burr-hole only procedure, and 65% with burr-holes with drains. Clinical outcome results showed that 64% of twist-drill and CSD patients deteriorated as compared with 16% of those with burr-hole only and 7% with burr-holes and CSDs. Sixty-four per cent of twist-drill patients required repeat evacuations as compared with 11% of those with burr-holes only, and 7% with burr-holes plus drains. CONCLUSION: The results at our institution indicate that burr-hole evacuation for chronic subdural haematoma is superior to twist-drill evacuation with respect to clinical outcomes and complications.

Adolescent↗

The evolutionary history of the coral genus Acropora (Scleractinia, Cnidaria) based on a mitochondrial and a nuclear marker: reticulation, incomplete lineage sorting, or morphological convergence?

This study examines molecular relationships across a wide range of species in the mass spawning scleractinian coral genus Acropora. Molecular phylogenies were obtained for 28 species using DNA sequence analyses of two independent markers, a nuclear intron and the mtDNA putative control region. Although the compositions of the major clades in the phylogenies based on these two markers were similar, there were several important differences. This, in combination with the fact that many species were not monophyletic, suggests either that introgressive hybridization is occurring or that lineage sorting is incomplete. The molecular tree topologies bear little similarity to the results of a recent cladistic analysis based on skeletal morphology and are at odds with the fossil record. We hypothesize that these conflicting results may be due to the same morphology having evolved independently more than once in Acropora and/or the occurrence of extensive interspecific hybridization and introgression in combination with morphology being determined by a small number of genes. Our results indicate that many Acropora species belong to a species complex or syngameon and that morphology has little predictive value with regard to syngameon composition. Morphological species in the genus often do not correspond to genetically distinct evolutionary units. Instead, species that differ in timing of gamete release tend to constitute genetically distinct clades.

Animals↗

High ethanol consumption and low sensitivity to ethanol-induced sedation in protein kinase A-mutant mice.

Both in vitro and in vivo evidence indicate that cAMP-dependent protein kinase (PKA) mediates some of the acute and chronic cellular responses to alcohol. However, it is unclear whether PKA regulates voluntary alcohol consumption. We therefore studied alcohol consumption by mice that completely lack the regulatory IIbeta (RIIbeta) subunit of PKA as a result of targeted gene disruption. Here we report that RIIbeta knockout mice (RIIbeta-/-) showed incr eased consumption of solutions containing 6, 10, and 20% (v/v) ethanol when compared with wild-type mice (RIIbeta+/+). On the other hand, RIIbeta-/- mice showed normal consumption of solutions containing either sucrose or quinine. When compared with wild-type mice, the RIIbeta-/- mice were found to be less sensitive to the sedative effects of ethanol as measured by more rapid recovery from ethanol-induced sleep, even though plasma ethanol concentrations did not differ significantly from those of controls. Finally, both RIbeta- and catylatic subunit beta1-deficient mice showed normal voluntary consumption of ethanol, indicating that increased ethanol consumption is not a general characteristic associated with deletion of PKA subunits. These data demonstrate a role for the RIIbeta subunit of PKA in regulating voluntary consumption of alcohol and sensitivity to the intoxication effects that are produced by this drug.

Alcohol Drinking↗

A clinical pathway for inguinal hernia repair reduces hospital admissions.

BACKGROUND: Clinical pathways have been advocated as a means to improve and standardize patient care while reducing costs through improved efficiency. This study examines the hypothesis that development of a clinical pathway reduces hospital admissions in a Veterans Affairs (VA) medical center. MATERIALS AND METHODS: For the year prior to June 1997, 168 elective inguinal herniorrhaphies were performed. This constituted the prepathway (pre-P) group. One hundred ninety-six elective inguinal herniorrhaphies were performed during the year following institution of the clinical pathway-the postpathway (post-P) group. RESULTS: Hospital admissions were compared between the two groups. In the pre-P group 61 of the 168 patients (36%) were admitted while 29 of the 196 patients (15%) in the post-P group were admitted (P < 0.001). In the pre-P group 27 of the 53 patients reviewed (51%) had either no justification or inadequate justification for admission. In the post-P group 8 of the 29 patients admitted (28%) had inadequate justification (pre-P vs post-P, P = 0.124). Common reasons for admission included pain, perioperative complications, and concurrent medical problems or surgical procedures. The most common single cause other than pain was urinary retention. The average age of patients requiring admission was greater both pre-P and post-P. CONCLUSIONS: We conclude that institution of a clinical pathway for inguinal herniorrhaphy decreased hospital admissions. The reasons for this decrease are probably multifactorial and include improvements in physician and staff awareness. The decrease in unnecessary admissions should result in more efficient use of hospital resources.

Age Factors↗

Infertility treatment and multiple birth rates in Britain, 1938-94.

Trends in multiple birth rates are thought to have been substantially affected by subfertility treatments in the last 25 years, but there are few quantitative assessments of this. This paper examines trends in twin and higher multiple birth rates separately in Scotland, England and Wales and compares their course with corresponding multiple birth rates in the Oxford Record Linkage Study area, where the proportions following subfertility treatment are documented. National data on prescriptions for subfertility treatments reinforce the view that they have had a major effect on the trends, and currently perhaps 60% of triplet and higher order births and 15% of twins follow their use in Britain.

Birth Rate↗

Disease course and late sequelae of Langerhans' cell histiocytosis: 25-year experience at the University of California, San Francisco.

PURPOSE: The purpose of our investigation was to correlate the extent and degree of organ involvement at presentation of Langerhans' cell histiocytosis (LCH) with subsequent disease course, survival, and late sequelae. MATERIALS AND METHODS: The medical records of 71 patients with a pathologic diagnosis of LCH, age 0 to 21 years, who presented between January 1, 1969 and June 30, 1994, were reviewed for organ involvement at diagnosis, treatment, disease course, and late sequelae. Supplementary data were obtained by mailed questionnaire. RESULTS: The median follow-up time from diagnosis for all patients was 8.1 years. Involvement at diagnosis included nine patients with skin-only disease, 22 with monostotic disease, 12 with polyostotic disease, and 28 with multisystem presentation. Treatment was surgery only in 17 and chemotherapy and/or radiotherapy in 54 patients. Recurrences were seen in 35 patients, with the highest rate in the polyostotic group. Ten patients died: seven with the multisystem presentation, two with monostotic disease, and one with skin-only disease. Causes included progressive LCH (n = 6) and late sequelae of either treatment (n = 3) or disease (n = 1). Late sequelae were seen in 64% of 51 patients with more than 3 years of follow-up data. The most common were skeletal defects in 42%, dental problems in 30%, diabetes insipidus in 25%, growth failure in 20%, sex hormone deficiency in 16%, hypothyroidism in 14%, hearing loss in 16%, and other CNS dysfunction in 14%. The overall estimated survival rates at 5, 15, and 20 years are 88%, 88%, and 77%, with an estimated event-free survival rate of only 30% at 15 years. CONCLUSION: Despite the favorable survival, more than half of LCH patients will have further dissemination of disease or late sequelae, including even some patients with single-system disease at diagnosis. Future treatment needs to be designed to prevent disease progression and late sequelae.

Adolescent↗

Pediatric spinal blastomycosis: case report.

A 5-year-old male patient presented with flank pain, limping, weight loss, and cachexia. Magnetic resonance imaging revealed destructive vertebral changes, an epidural mass, psoas abscesses, and lack of involvement of the disc spaces. Blastomyces dermatitidis was isolated from a needle aspiration specimen. Sparing of the disc spaces, an unusual finding, suggested that the spread of infection was by way of paravertebral structures and surrounding potential spaces. Management was simplified by using gadolinium contrast-enhanced magnetic resonance imaging, which indicated that the epidural mass was mainly solid, thereby obviating abscess drainage.

Amphotericin B↗

Developments in three-dimensional stereo brightfield microscopy.

We present recent developments of a widefield computer/microscope system and image reconstruction algorithm for producing three-dimensional (3D) increased depth of field images in the form of brightfield stereo pairs of thick specimens. The theoretical principle of this image reconstruction technique is based on Weiner-type inverse filtering. A number of extensions and refinements to our previous work have included further testing of the system with a broader class of specimens and the implementation of several pragmatic refinements important for future 3D microscopy systems. These refinements include histogram modification routines for improving visualization, a preprocessing routine to eliminate edge artifacts due to circular convolution and other effects, stereo viewing angle optimization, a rule of thumb estimate for the axial sampling rate, and incorporation of a variation of the Fast Fourier Transform and filtering operations that significantly reduce computational time. Images of spyrogyra, neonatal rat hippocampal neurons, and cervical/vaginal cell smears are presented to show the utility of these methods for 3D visualization. The primary advantages of these methods are that they operate with an ordinary transmitted light microscope and are inexpensively implemented on a personal computer with reasonable computation time.

Algorithms↗

Iterative, constrained 3-D image reconstruction of transmitted light bright-field micrographs based on maximum likelihood estimation.

We present several image reconstruction algorithms for generating three-dimensional (3-D) renderings of bright-field micrographs that are founded on maximum likelihood estimation (MLE) theory. The basic principle of the algorithms is in estimating the values of the optical densities of the specimen. A computer simulation and initial experimental testing of a steepest ascent version of the algorithm is presented. The computer simulation demonstrates that the MLE algorithm has an advantage over previously used inverse filtering techniques in that it partially restores the zeroed Fourier components in the well-known missing-cone region. We present 3-D reconstructions from real biological data to show the potential of the algorithm in practical applications.

Algorithms↗