Search PubMed⌕ Search

Biomedical subjects

J P McKenna

Publications and source records attributed to J P McKenna.

At least 19 recordsLinked to original sources
PubMed2005

Survival of Campylobacter jejuni in waterborne protozoa.

The failure to reduce the Campylobacter contamination of intensively reared poultry may be partially due to Campylobacter resisting disinfection in water after their internalization by waterborne protozoa. Campylobacter jejuni and a variety of waterborne protozoa, including ciliates, flagellates, and alveolates, were detected in the drinking water of intensively reared poultry by a combination of culture and molecular techniques. An in vitro assay showed that C. jejuni remained viable when internalized by Tetrahymena pyriformis and Acanthamoeba castellanii for significantly longer (up to 36 h) than when they were in purely a planktonic state. The internalized Campylobacter were also significantly more resistant to disinfection than planktonic organisms. Collectively, our results strongly suggest that protozoa in broiler drinking water systems can delay the decline of Campylobacter viability and increase Campylobacter disinfection resistance, thus increasing the potential of Campylobacter to colonize broilers.

Acanthamoeba castellanii↗
PubMed2003

Antimicrobial susceptibility of Campylobacter spp. isolated from broiler chickens in Northern Ireland.

Between February 2000 and October 2001, cloacal swabs were collected from 387 broiler chicken flocks in Northern Ireland. Campylobacter isolates from the 262 positive flocks were tested with common antimicrobial agents using a disc diffusion method and by Etests. Resistance to erythromycin, gentamicin and chloramphenicol was <1%, whereas for ampicillin, nalidixic acid and tetracycline, resistance was 33%, 10% and 13%, respectively. Ciprofloxacin resistance was 3%, one of the lowest in recent reports from studies on human or poultry isolates. Sequence data of the quinolone resistance-determining region of the gyrA gene showed a mutation leading to Thr-86 to Ile substitution among highly resistant ciprofloxacin isolates. Only 0.8% of the isolates studied were resistant to four or more antibiotics.

Animals↗
PubMed1999

Are higher doses of nicotine replacement more effective for smoking cessation?

This study determined whether higher dose nicotine patches are more efficacious than lower dose patches among heavy smokers. A randomized double-blind study compared 0, 21, 35, and 42 mg/day of a 24-h patch in 1039 smokers (> or = 30 cigarettes/day) at 12 clinical sites in the USA and one in Australia. Daily patches were used for 6 weeks followed by tapering over the next 10 weeks. Weekly group therapy occurred. Biochemically validated self-reported quit rates at 6, 12, 26, and 52 weeks post-cessation were measured. Quit rates were dose-related at all follow-ups (p < 0.01). Continuous, biochemically verified abstinence rates for the 0, 21, 35, and 42 mg doses at the end of treatment (12 weeks) were 16, 24, 30, and 39%. At 6 months, the rates were 13, 20, 20, and 26%. Among the 11 sites with 12 month follow-up (n = 879), the quit rates were 7, 13, 9, and 19%. In post-hoc tests, none of the active doses were significantly different from each other at any follow-up. The rates of dropouts due to adverse events for 0, 21, 35, and 42 mg were 3, 1, 3, and 6% (p = n.s.). Our results are similar to most prior smaller studies; i.e., in heavy smokers higher doses increase quit rates slightly. Longer durations of treatment may be necessary to show greater advantages from higher doses.

Administration, Cutaneous↗
PubMed1996

A comparison of the haemagglutinating and enzymic activities of Bacteroides fragilis whole cells and outer membrane vesicles.

The haemagglutinating and enzymic activities of the obligately anaerobic pathogenic bacterium Bacteroides fragilis were examined. Outer membrane vesicles are released from the surface of B. fragilis. They can be detected by electron microscopy in ultrathin sections and bacterial suspensions after negative staining. Electron microscopy and immunogold labelling with a MAb specific for surface polysaccharide of B. fragilis confirmed that the vesicles carried outer membrane associated epitopes. The haemagglutinating activity of whole cells from populations of B. fragilis strains NCTC9343, BE3 and LS66 enriched by Percoll density gradient centrifugation for a large capsule (LC), electron dense layer (EDL); non-capsulate by light microscopy) and outer membrane vesicles (OMV) which had been purified by centrifugation from EDL-enriched populations were compared using human and horse erythrocytes. The enzymic activity of OMV, LC- and EDL-enriched populations, as detected by the API ZYM kit, was compared for strains NCTC 9343 and BE3. Purified OMV from the strains examined exhibited both haemagglutinating and enzymatic activity. Haemagglutination by the EDL-enriched population was sensitive to treatment with sodium periodate. The LC-enriched population haemagglutinated only after ultrasonic removal of the capsule. This indicates that the LC masks a haemagglutinin. The results suggest a potential role for OMV in the virulence of B. fragilis.

Animals↗
PubMed1995

The alpha isoform of protein kinase C inhibits histamine-stimulated adenylate cyclase activity in a particulate fraction of the human gastric cancer cell line HGT-1.

The isoform of protein kinase C responsible for the inhibition of histamine-stimulated adenylate cyclase by the phorbol ester, 12-O-tetradecanoylphorbol 13-acetate (TPA), has been investigated in a particulate fraction prepared from the human gastric cancer cell line HGT-1. The alpha and epsilon isoforms of protein kinase C were detected in HGT-1 cells and in a 40,000 x g particulate fraction by immunoblotting procedures. The inhibitory effect of TPA on histamine-stimulated adenylate cyclase was enhanced by the presence of Ca2+, but decreased in a concentration-dependent manner by anti-peptide antibody to protein kinase C alpha, but not to protein kinase C epsilon. Addition of Ca2+ and TPA to the 40,000 x g particulate fraction stimulated the phosphorylation of the protein kinase C substrate myelin basic peptide 4-14. Protein kinase C alpha is probably the isoform responsible for inhibition of histamine-stimulated adenylate cyclase in HGT-1 cells.

Adenylyl Cyclase Inhibitors↗
PubMed1995

OTC nicotine gum.

Explore the source record for details and available documents.

Chewing Gum↗
PubMed1995

Cigarette availability to minors.

Each year, more than 1 million children and adolescents begin smoking, and an average of 24% of high school students report smoking, despite existing laws that prohibit the sale of tobacco to minors. In this study, the authors observed an 11-year-old boy attempt to purchase cigarettes at 57 retail establishments in western Pennsylvania to determine if the existing laws do, indeed, limit children's access to buy cigarettes. This study took place between August 15, 1993, and October 2, 1993. The establishments included convenience stores, gas stations, liquor distributors, and restaurants. One of the researchers entered each establishment to look for the posting of the state law prohibiting the sale of cigarettes to minors after their underage subject had requested cigarettes from the salesclerks. The researcher also inquired of the salesclerks if they were aware of the state law. In 30 of the 57 attempts (53%), the 11-year-old student would have been able to purchase cigarettes. Of these attempts, 53% would have sold them on his first request, while 47% would have sold them to him if he indicated that the cigarettes were for his dad. Only 3 of the 57 establishments (5.2%) posted the law, and 54 of the 57 clerks (95%) were aware of the cigarette law.

Adolescent↗
PubMed1993

Inhibition by Ro 31-8220 of acid secretory activity induced by carbachol indicates a stimulatory role for protein kinase C in the action of muscarinic agonists on isolated rat parietal cells.

The bisindolylmaleimide Ro 31-8220 is a selective inhibitor of protein kinase C. This compound was used to investigate the involvement of protein kinase C in the stimulation of gastric acid secretion by the muscarinic cholinergic receptor on rat isolated parietal cells. The accumulation of the weak base aminopyrine by both crude and enriched preparations of parietal cells was used as an index of secretory activity. Ro 31-8220 antagonized (IC50, 1.0 microM) the effect of the activator of protein kinase C,12-O-tetradecanoylphorbol 13-acetate (TPA), on histamine-stimulated aminopyrine accumulation. Ro 31-8220 (0.1-2.14 microM) inhibited the aminopyrine response to 0.1 mM carbachol (IC50, 0.78 microM; 49% inhibition at 2.14 microM Ro 31-8220) and shifted the dose-response curve for the effect of carbachol concentration of aminopyrine accumulation downwards and to the right. No inhibition of aminopyrine accumulation induced by histamine was found with Ro 31-8220 (0.1-2.14 microM). In a preparation containing > 80% parietal cells incubated with 0.1 mM carbachol, 2.14 microM Ro 31-8220 inhibited aminopyrine accumulation by 43%, but had no effect on the increase in intracellular Ca2+ which was measured by using the fluorescent probe FURA-2. In conclusion, Ro 31-8220 (0.1-2.14 microM) produced a selective reduction in secretory activity in parietal cells by inhibition of protein kinase C. The predominant role of protein kinase C in parietal cells activated with carbachol is not to cause feedback inhibition of the response but to facilitate stimulation of secretory activity.

Aminopyrine↗
PubMed1992

Transdermal nicotine replacement and smoking cessation.

Transdermal nicotine systems are a useful adjunct to smoking cessation. The larger-sized nicotine patches provide steady-state replacement of approximately 50 percent of the average serum nicotine level obtained by smoking one to one and one-half packs of cigarettes a day. This level is sufficient to prevent many symptoms of nicotine withdrawal, including physical craving, irritability, anxiety, restlessness, hostility, hunger and difficulty concentrating. In double-blind, placebo-controlled trials, transdermal nicotine systems have been about twice as successful as placebo in helping patients stop smoking.

Administration, Cutaneous↗
PubMed1991

Laryngeal cancer: diagnosis, treatment and speech rehabilitation.

Cancer of the larynx occurs most often in men between 50 and 70 years of age. Cigarette smoking and alcohol are responsible for more than 75 percent of cases. Hoarseness is the most common presenting complaint. If hoarseness persists for more than two weeks, laryngoscopy is indicated. Clinical staging utilizes direct laryngoscopy, esophagoscopy and bronchoscopy to exclude synchronous malignancies. The five-year cure rate, with preservation of voice and glottic function, is as high as 90 percent if the lesions of the vocal cords are found in an early stage. Total laryngectomy is required for more extensive disease. Speech rehabilitation has been revolutionized by tracheoesophageal speech techniques.

Bronchoscopy↗
PubMed1990

Nicotine gum: does providing it free in a smoking cessation program alter success rates?

Successful strategies to enhance smoking cessation are important in family medicine. Many facets of smoking-cessation programs have been evaluated to determine their effectiveness in contributing to success. One factor that has not been investigated is the effect of cost to the smoker of nicotine gum. A retrospective analysis of the 1-year sustained (lapse-free abstinence) success rates of 375 participants in a smoking-cessation program, led by family physicians, revealed that participants who were provided nicotine gum by their employer had a significantly higher 1-year success rate (38% vs 27%) than those who purchased the gum individually.

Adolescent↗
PubMed1989

Abnormal liver function tests in asymptomatic patients.

Liver function abnormalities are often found on routine chemical profiles. Abnormal test results are often false positive in asymptomatic patients. Repeat testing and confirmation that the liver is the source of the abnormality are the first steps of evaluation. A thorough history and physical examination may suggest reasons for the abnormalities. If no etiology for the abnormal test result is found, further testing is indicated.

Adult↗
PubMed1989

Metabolic acidosis with an elevated anion gap.

Determining the cause of metabolic acidosis with a high anion gap may present a diagnostic challenge. Possible causes include ketoacidosis, certain toxic ingestions, renal failure and lactic acidosis. Many of these entities present with nausea, vomiting and changes in mental status; however, there are specific hallmarks in the signs, symptoms and laboratory findings that help to differentiate among them.

Acid-Base Equilibrium↗
PubMed1988

Vaginal birth after cesarean section. A safe option in carefully selected patients.

The rate of cesarean section has risen steadily in the United States since 1970. During the same period, a trial of labor in patients who have had a cesarean section has also increased somewhat in popularity. Trial of labor has been demonstrated to be a safe and reasonable alternative to repeat cesarean section in carefully selected patients. If such a trial were offered to half of eligible patients and the success rate were only 50%, the cesarean section rate would be reduced to 19%. This reduction would represent 72,000 fewer cesarean births per year. Based on a savings of $3,000 per vaginal delivery, the total cost savings would be more than $200,000,000.

Adult↗
PubMed1988

Cluster headaches.

Cluster headaches are episodes of excruciating unilateral facial pain, typically occurring in young men. Ipsilateral autonomic symptoms of nasal congestion, rhinorrhea, conjunctival injection and lacrimation are commonly present. Characteristic facial features may be found. Migraine and trigeminal neuralgia are two important considerations in the differential diagnosis. Prednisone and lithium are effective prophylactic medications for episodic and chronic forms of cluster headaches. Treatment with oxygen or ergotamines may be useful in aborting attacks.

Adult↗
PubMed1987

Sialolithiasis.

Sialolithiasis occurs most commonly in the submandibular gland. The vast majority of salivary stones are single, with only 3 percent occurring bilaterally. Patients with distal submandibular stones may be treated with simple sialolithotomy. Other causes of salivary gland enlargement include mumps, tumors, acute suppurative sialadenitis and granulomatous disease.

Adult↗