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Biomedical subjects

K McBride

Publications and source records attributed to K McBride.

At least 19 recordsLinked to original sources
PubMed2006

Men with broken condoms: who and why?

OBJECTIVES: To identify (1) the prevalence of condom breakage, and demographic and sexuality-related differences among young men who have sex with women reporting and not reporting this event; (2) condom-specific behaviours associated with breakage. METHODS: Young men (n = 278) attending a clinic for treatment of sexually transmitted infections (STIs) responded to an anonymous questionnaire aided by a CD recording of the questions. The samples were screened to include only men who had used a condom during penile-vaginal sex at least three times in the past 3 months. Condom-specific behaviours (including breakage) were assessed using these last three acts of condom use as the recall period. Correlates achieving bivariate significance were subjected to multivariate analysis. RESULTS: Nearly one third (31.3%) of the men reported recent breakage. The breakage rate was 15%. Three correlates significantly distinguished between men who did and did not report breakage. Men who had past STIs were more likely to report breakage (adjusted odds ratio (AOR) 2.08), as were men who also reported condom slippage (AOR 2.72). Less self-efficacy for correct condom use was also significantly associated with breakage (AOR 1.07). Further, three condom-specific behaviours were significantly associated with breakage: allowing condoms to contact sharp objects (AOR 2.6), experiencing problems with the "fit or feel" of condoms (AOR 2.3) and not squeezing air from the receptacle tip (AOR 2.0). CONCLUSIONS: Breakage may be common and may occur in a larger context of difficulties with condoms. STI clinics could potentially benefit some men by providing instructions on the correct use of condoms.

Adult↗
PubMed2005

Influence of dietary crude protein concentration and source on potential ammonia emissions from beef cattle manure.

Emissions of ammonia, as well as other gases and particulates, to the atmosphere are a growing concern of livestock producers, the general public, and regulators. The concentration and ruminal degradability of CP in beef cattle diets may affect urinary and fecal excretion of N and thus may affect ammonia emissions from beef cattle feed yards. To determine the effects of dietary CP concentration and degradability on potential ammonia emissions, 54 steers were randomly assigned to nine dietary treatments in a 3 x 3 factorial arrangement of treatments. Treatments consisted of three dietary CP concentrations (11.5, 13, and 14.5%) and three supplemental urea:cottonseed meal ratios (100:0, 50:50, and 0:100 of supplemental N). Steers were confined to tie stalls, and feces and urine excreted were collected and frozen after approximately 30, 75, and 120 d on feed. One percent of daily urine and feces excretion were added to polyethylene chambers containing 1,550 g of soil. Chambers were sealed, and ammonia emissions were trapped in an acid solution for 7 d using a vacuum system. As the protein concentration in the diet increased from 11.5 to 13%, in vitro daily ammonia emissions increased (P < 0.01) 60 to 200%, due primarily to increased urinary N excretion. As days on feed increased, in vitro ammonia emissions also increased (P < 0.01). Potential ammonia losses were highly correlated (P < 0.01) to urinary N (r2 = 0.69), urinary urea-N (r2 = 0.58) excretion, serum urea-N concentration (r2 = 0.52), and intake of degradable protein N (r2 = 0.23). Although dietary composition can affect daily ammonia losses, daily ammonia emissions must be balanced with effects on animal performance to determine optimal protein concentrations and forms in the diet.

Ammonia↗
PubMed2003

Influence of oscillating dietary crude protein concentration on performance, acid-base balance, and nitrogen excretion of steers.

Decreasing dietary N inputs into beef cattle feeding operations could potentially decrease environmental concerns relating to air and water quality. Previous studies with sheep suggest that oscillating dietary CP concentrations may improve N use efficiency and thereby decrease dietary N requirements. Therefore, two studies were conducted to determine the effects of oscillating dietary CP concentrations on performance, acid-base balance, and manure characteristics of steers fed high-concentrate diets. Steers were fed to a constant backfat thickness in both studies. In the first trial, 92 steers (mean BW = 408 +/- 2.8 kg; four pens/treatment) were fed the following diets: 1) constant 12% CP, 2) constant 14% CP, and 3) 10 and 14% CP oscillated at 2-d intervals. Steer performance and carcass characteristics were measured. In the second trial, 27 steers were individually fed the same three experimental dietary regimens (nine steers/treatment). Animal performance, arterial acid-base balance, plasma metabolites, and fecal characteristics were measured. In both trials, steers fed the 14% CP diet tended (P < 0.10) to have greater ADG and gain:feed than steers fed the 12% CP diet. Steers fed the oscillating CP regimen had intermediate performance. In Trial 1, steers fed the 14% CP diet tended (P = 0.09) to have smaller longissimus area and higher quality grades than steers fed the oscillating CP regimen. Protein retentions (g/d) calculated from NRC (2000) equations were greater (P = 0.04) for steers fed the 14% CP diet than steers fed the 12% CP diet. Steers fed the oscillating CP regimen tended (P = 0.08) to have greater calculated protein retention (g/d) than steers fed the 12% CP diet. Steers fed the 14% CP diet had greater (P < 0.05) calculated urinary N excretion than steers fed the 12% CP or oscillating CP regimens. Venous plasma concentrations of urea N were greater (P < 0.001) in steers fed the 14% CP diet than in steers fed the 12% CP diet; steers fed the oscillating CP regimen were intermediate but fluctuated over days. Based on arterial blood gas concentrations, acid-base balance was not significantly affected by dietary CP regimen. Results of these trials suggest that the CP requirement of steers in these studies was greater than 12% of the diet DM, and/or that the degradable CP requirement was greater than 6.3% of diet DM. However, the effects of oscillating dietary CP were minimal.

Acid-Base Equilibrium↗
PubMed2001

Regulation of the ANF and BNP promoters by GATA factors: lessons learned for cardiac transcription.

The identification and molecular cloning of the cardiac transcription factors GATA-4, -5, and -6 has greatly contributed to our understanding of how tissue-specific transcription is achieved during cardiac growth and development. Through analysis of their interacting partners, it has also become apparent that a major mechanism underlying spatial and temporal specificity within the heart as well as in the response to cardiogenic regulators is the combinatorial interaction between cardiac-restricted and inducible transcription factors. The cardiac GATA factors appear to be fundamental contributors to these regulatory networks. Two of the first targets identified for the cardiac GATA factors were the natriuretic peptide genes encoding atrial natriuretic factor (ANF) and B-type natriuretic peptide (BNP), the major heart secretory products that are also accepted clinical markers of the diseased heart. Studies using the ANF and BNP promoters as models of cardiac-specific transcription have unraveled the pivotal role that GATA proteins play in cardiac gene expression. We review the current knowledge on the modulation of the natriuretic peptide promoters by GATA factors, including examples of combinatorial interactions between GATA proteins and diverse transcription factors.

Animals↗
PubMed2000

Secondary hypoxemia exacerbates the reduction of visual discrimination accuracy and neuronal cell density in the dorsal lateral geniculate nucleus resulting from fluid percussion injury.

The purpose of this study was to determine the impact of secondary hypoxemia on visual discrimination accuracy after parasagittal fluid percussion injury (FPI). Rats lived singly in test cages, where they were trained to repeatedly execute a flicker-frequency visual discrimination for food. After learning was complete, all rats were surgically prepared and then retested over the following 4-5 days to ensure recovery to presurgery levels of performance. Rats were then assigned to one of three groups [FPI + Hypoxia (IH), FPI + Normoxia (IN), or Sham Injury + Hypoxia (SH)] and were anesthetized with halothane delivered by compressed air. Immediately after injury or sham injury, rats in groups IH and SH were switched to a 13% O2 source to continue halothane anesthesia for 30 min before being returned to their test cages. Anesthesia for rats in group IN was maintained using compressed air for 30 min after injury. FPI significantly reduced visual discrimination accuracy and food intake, and increased incorrect choices. Thirty minutes of immediate posttraumatic hypoxemia significantly (1) exacerbated the FPI-induced reductions of visual discrimination accuracy and food intake, (2) further increased numbers of incorrect choices, and (3) delayed the progressive recovery of visual discrimination accuracy. Thionine stains of midbrain coronal sections revealed that, in addition to the loss of neurons seen in several thalamic nuclei following FPI, cell loss in the ipsilateral dorsal lateral geniculate nucleus (dLG) was significantly greater after FPI and hypoxemia than after FPI alone. In contrast, neuropathological changes were not evident following hypoxemia alone. These results show that, although hypoxemia alone was without effect, posttraumatic hypoxemia exacerbates FPI-induced reductions in visual discrimination accuracy and secondary hypoxemia interferes with control of the rat's choices by flicker frequency, perhaps in part as a result of neuronal loss and fiber degeneration in the dLG. These results additionally confirm the utility of this visual discrimination procedure as a sensitive, noninvasive means of assessing behavioral function after experimental traumatic brain injury.

Animals↗
PubMed1999

The use of endovascular stents in the treatment of penetrating ulcers of the thoracic aorta.

Penetrating atheromatous ulcers of the aorta are increasingly recognized as a distinct entity. Although their natural history remains ill-defined, such ulcers may lead to pseudoaneurysmal formation, dissection, rupture, or embolization. Given the morbidity associated with open repair, endovascular repair of penetrating atheromatous ulcers may be the treatment of choice. Although stent-graft replacement of acute aortic dissections has recently been described, endovascular repair of penetrating thoracic aortic ulcers has not previously been reported. We report two cases of successful endovascular repair of penetrating atheromatous ulcers that previously ruptured.

Aged↗
PubMed1999

Vascular surgical society of great britain and ireland: percutaneous transluminal angioplasty for lower limb ischaemia

BACKGROUND: Percutaneous transluminal angioplasty (PTA) is increasingly performed for lower limb ischaemia of all severities, despite the absence of controlled data demonstrating its efficacy. The aim of this study was to examine the indications and outcome for lower limb ischaemia over a 16-year period. METHODS: A prospectively gathered database of 1287 consecutive PTAs performed between 1982 and 1997 was analysed. Two time intervals were compared: 1982-1991 and 1992-1997. RESULTS: Since 1992 there has been a fourfold increase in the number of PTAs performed. There has been a significant increase in the number of PTAs performed for critical ischaemia, occlusive lesions and at infrainguinal sites. Although there has been a significant reduction in morbidity, the number of immediate technical and clinical failures has increased (see Table ). CONCLUSION: Despite a lack of controlled data supporting a more liberal use of PTA in the treatment of lower limb ischaemia, there has been, in this regional vascular unit, a significant increase in the perceived clinical and anatomical indications for the procedure. Randomized controlled trials are urgently required to define the role of PTA in this condition.

Journal Article↗
PubMed1999

Vascular surgical society of great britain and ireland: outcome of iliac percutaneous transluminal angioplasty with and without the use of stents in patients with intermittent claudication

BACKGROUND: Despite the absence of controlled data supporting endovascular treatment of iliac disease in patients with intermittent claudication (IC), there has been a significant increase in iliac percutaneous transluminal angioplasty (PTA), and in particular iliac stenting, in recent years. The clinical and haemodynamic outcome of iliac PTA, with and without stenting, was assessed in patients with IC. METHODS: A prospectively gathered computerized database of iliac PTA (n = 203) and stenting (n = 88), performed between 1 January 1991 and 31 December 1997, was analysed. RESULTS: Occlusive disease was significantly more likely than stenotic disease to be treated by primary stent deployment (19 of 88, 22 per cent) than PTA alone (11 of 203, 5 per cent) (P < 0.01, chi2 test), as were lesions in the common iliac artery (common 69 of 214 (32 per cent) versus external 14 of 65 (22 per cent); P < 0.05, chi2 test). Primary stent placement was associated with a significant increase in morbidity that delayed hospital stay (13 of 88 (15 per cent) versus seven of 203 (3 per cent); P < 0.05, chi2 test). Emergency revascularization was required in four patients who underwent PTA (2 per cent) and two who had stenting (2 per cent) (P not significant). CONCLUSION: Iliac stenting is associated with a significant increase in morbidity but with no improvement in symptomatic or haemodynamic outcome. These results do not justify the increased expense associated with the routine use of iliac stents.

Journal Article↗
PubMed1998

Expression of feline recombinant interferon-gamma in baculovirus and demonstration of biological activity.

We have previously reported the cloning of the coding sequence for feline-specific interferon-gamma. Here, we describe the expression of this sequence in a baculovirus system and demonstrate the biological activity of the recombinant protein. The coding sequence for feline interferon was directionally cloned into the baculovirus transfer vector pAcCL29-1. Transfer vector and linearized wild-type AcMNPV (BacPAK6) were used to co-transfect Sf9 cells by calcium phosphate coprecipitation. Subsequently, wild-type and recombinant viruses were separated by plaque assay. Recombinant plaques were expanded and a master stock of virus is produced. Production of biologically active interferon-gamma from infected Sf9 cells was demonstrated using a standard cytopathic effect reduction assay, utilising vesicular stomatitis virus (VSV), and an MHC class II induction assay.

Animals↗
PubMed1998

The C-terminal domain of c-fos is required for activation of an AP-1 site specific for jun-fos heterodimers.

The proto-oncogenes jun and fos are members of the AP-1 family of transcription factors, which activate transcription of target genes via the tetradecanoyl phorbol acetate response element (TRE). Both jun and fos contain activation domains, but their relative contributions to transcriptional activation of different TREs remain unclear. It is not apparent whether the cellular availability of specific AP-1 members is the major determinant for regulation of TREs or whether other factors including the TRE sequence itself contribute to selectivity. We have identified in the promoter of the rat atrial natriuretic factor (ANF) a novel AP-1 site which is unresponsive to jun homodimers and is inducible only in the presence of c-fos. This activation is potentiated by mitogen-activated protein (MAP) kinase. The jun proteins appear to be required solely to tether c-fos to the promoter, and c-fos mutants lacking putative activation domains abrogate transactivation. Unexpectedly, the oncogenic form of c-fos which diverges most significantly in the carboxy-terminal 50 amino acids is unable to mediate transactivation at this specialized AP-1 site. Mutations within the C terminus of c-fos at serine residues that are phosphorylation targets for growth factors and MAP kinase completely abrogate transactivation and block potentiation by MAP kinase. Using GAL4 fusions, we show that the 90-amino-acid C terminus of c-fos contains autonomous activation domains and that the serine residues are essential for full activity. These results suggest that phosphorylation of the C terminus of c-fos affects its transactivation properties and provide evidence for novel regulatory mechanisms that may contribute to biologic specificities of the AP-1 transcription complex.

Animals↗
PubMed1995

Mesenteric ischaemia: a multidisciplinary approach.

Mesenteric ischaemia may result from a wide range of pathological processes, each possessing unique clinical features, diagnostic difficulties, management strategies and outcome. Regardless of aetiology, prognosis depends crucially on rapid diagnosis and institution of treatment to prevent, or at least to minimize, bowel infarction. Progress in understanding the pathophysiology of mesenteric ischaemia has led to novel methods of treatment, so that in some circumstances therapy may be purely medical. More often surgery is required and is frequently life saving. Percutaneous transcatheter techniques are increasingly employed in both diagnosis and treatment. Close cooperation between radiologists, physicians and surgeons is therefore necessary if clinical outcome is to be optimized. This paper reviews the modern interdisciplinary management of mesenteric ischaemia in the light of recent advances.

Acute Disease↗
PubMed1995

Nucleotide and predicted peptide sequence of feline interferon-gamma (IFN-gamma).

Interferon gamma is a pleiotropic cytokine which is now recognised as an important modulator of the immune response. We now report the cloning and sequencing of feline interferon gamma cDNA which was generated by the polymerase chain reaction. At the nucleotide level feline ifn-gamma shares 78% and 63% homology with human and murine cDNA equivalents. At the amino acid level the feline IFN-gamma shares 63% and 43% homology with human and murine homologs respectively.

Amino Acid Sequence↗
PubMed1994

Superior vena caval obstruction managed by the Gianturco Z Stent.

Twenty patients with superior vena caval obstruction (SVCO) due to malignancy were managed using the Gianturco Z Stent. Three patients had adjunctive thrombolysis. The primary clinical success was 90% (18/20 patients). Thirteen patients were free of SVCO to death or follow-up without re-intervention (primary patency = 65%). Three patients had re-intervention for recurrent symptoms, two successfully (secondary long-term patency = 75%). Stenting of the SVC is a valuable, under-used technique for the symptomatic relief of superior vena caval obstruction.

Humans↗
PubMed1993

The DNA sequence of adenovirus type 40.

The 34,214 bp DNA sequence of adenovirus type 40 strain Dugan was determined directly from random fragments of virion DNA cloned into a bacteriophage M13 cloning vector. The gene layout is similar to that of other human adenoviruses, and in addition contains two potential protein-coding regions that are conserved, but have not been recognized previously, in other adenovirus genomes. One is oriented rightward, contained within the intron in the protein-coding region for the L4 33K gene, and would encode a protein sharing N-terminal sequence with 33K. The other is a leftward oriented exon located between the E3 and L5 IV (fibre) regions which would specify the N terminus of a novel protein. The region encoding the C terminus of this protein is not apparent from sequence data.

Adenoviruses, Human↗