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Biomedical subjects

A Allen

Publications and source records attributed to A Allen.

At least 109 records · Page 6Linked to original sources
PubMed1997

Effect of nicotine on large bowel mucus thickness, eicosanoids and faecal proteinase in ferrets.

BACKGROUND: Following observations on the effect of subcutaneous nicotine on rectal mucosal eicosanoids and mucus in the rabbit we have repeated the work in ferrets which may be a more suitable animal model. AIMS AND METHODS: The effect of nicotine on mucosal eicosanoids, the adherent mucus layer, and faecal proteinases in the large bowel of ferrets was examined in forty animals randomly allocated to five groups, a control and four treatment groups. They were given subcutaneous saline or nicotine via an Alzet pump in doses of 0.3, 0.6, 1.2 and 2.0 mg/kg/day for 10 days and then sacrificed; measurements were made of serum nicotine and cotinine levels, rectal mucosal eicosanoids, adherent rectal and colonic mucus thickness, and faecal proteinases. RESULTS: No significant differences were observed for any measurements, except for serum nicotine and cotinine levels, which were raised consistent with the dose given. CONCLUSION: Nicotine had no effect on measurements, which may possibly be important in the relationship between smoking and ulcerative colitis.

Animals↗
PubMed1997

Relationship between gastric mucus synthesis, secretion and surface gel erosion measured in amphibian stomach in vitro.

1. The layer of adherent mucus that protects the surface of the stomach reflects a dynamic balance between biosynthesis of glycoprotein, secretion of preformed mucus and erosion of the adherent gel layer. The present study is the first in which all these processes have been measured concomitantly and was undertaken to define interrelationships between the three parameters. 2. A chambered sac preparation of amphibian gastric mucosa is described. Biosynthesis was determined by specific incorporation of radiolabelled sugars into purified glycoprotein. Mucus secretion was determined by measuring the thickness of the adherent gel and erosion of the surface layer was assessed from the appearance of soluble mucin in the luminal solution. 3. 16,16-Dimethyl-prostaglandin (PG) E2 stimulated glucosamine incorporation by 10-fold, but did not alter the rate of incorporation of galactose. There was a rapid two-fold increase in the thickness of the adherent mucus layer but no change in the rate of erosion. Dibutyryl-cAMP also stimulated mucus release but, unlike PG, increased glycoprotein labelling by galactose. 4. Both distention or the application of a cholinergic agonist increased adherent mucus thickness. Stimulation of mucus release in response to carbachol was accompanied by a decrease in glycoprotein labelling by galactose. In contrast, the adrenergic agent noradrenaline decreased secretion but did not influence labelling. 5. These results indicate that biosynthesis and secretion of gastric mucus are subject to differential regulation. Moreover, the profile of incorporation of sugars in response to secretagogues also differs, indicating the need for caution when interpreting effects on glycoprotein biosynthesis.

16,16-Dimethylprostaglandin E2↗
PubMed1997

A cost analysis of a tele-oncology practice.

Costs were monitored for three different types of oncology practice: a telemedicine clinic and a fly-in outreach clinic, both held in rural areas, and a traditional clinic held in a city hospital. Total expenses were calculated over the year May 1995 to April 1996. The average cost per telemedicine visit was $812. The average cost per outreach clinic visit was $897. Flying in oncology support for this practice was therefore about 10% more costly than telemedicine. While the outreach cost may have been inappropriately high due to a slow start-up phase, it was still less expensive during this period to be seen via telemedicine. For comparison, the average cost per traditional oncology clinic visit was $149. However, this figure does not take into account the costs of access to a city-based service by rural patients.

Cost-Benefit Analysis↗
PubMed1997

Practising oncology via telemedicine.

Although there are increasing numbers of telemedicine programmes in the USA, few have offered teleoncology services, so that the role of telemedicine in the practice of clinical oncology has yet to be fully defined. Telemedicine has been used successfully for direct patient care in Kansas. It is also a method of providing supportive care for the cancer patient, including assessments of pain and nutrition. In addition, televised tumour conferences and nursing education courses can help smaller communities develop a level of expertise that allows patients to be treated locally. Telemedicine may well be used in future for access to national and international cancer experts, and for participation in new cancer treatment protocols through cooperative group trials. When practising oncology via telemedicine, there are unique problems, including issues regarding technology (interactive video and radiograph review) and practice (patient/oncologist preferences and doctor-patient communication). Very little has been published in the area of tele-oncology so far, and studies concerning its efficacy, cost-effectiveness and the best organizational structure are still in progress. However, telemedicine appears to be a useful technique in the practice of oncology.

Efficiency↗
PubMed1997

Association of genetic variations in apolipoprotein B with hypercholesterolemia, coronary artery disease, and receptor binding of low density lipoproteins.

To search for unique mutations in the apolipoprotein B (apoB) gene that disrupt the binding of LDL to its receptor and cause hypercholesterolemia, we examined more than 800 patients with high LDL cholesterol levels and/or coronary artery disease (CAD). Analysis of patient DNA by single-strand conformation polymorphism and allele-specific oligonucleotide hybridization of the sequence surrounding the putative receptor- binding domain of apoB (amino acid positions 2965 to 3534) revealed seven variations. LDL from heterozygotes with either Arg 3500 Gln or Arg 3531 Cys bound defectively with the LDL receptor in competitive binding assays. The Arg 3500 Gln substitution was statistically more prevalent in patients with hypercholesterolemia (P = 0.0003). Total cholesterol and LDL-cholesterol were significantly higher (P< 0.0004) in 34 apoB 3500 Gln carriers than in the controls. The allele encoding the Arg 3531 Cys substitution was more prevalent (0.8%) in the CAD group (P = 0.05) than in the controls. A Ser 3252 Gly variant was statistically more prevalent in the hypercholesterolemic group (P = 0.03), but LDL with this mutation had normal LDL receptor-binding activity. The other four variants identified (Leu 3350 Leu, Gln 3405 Glu, Val 3396 Met, and Ser 3455 Arg) were not associated with defective LDL-receptor binding, hypercholesterolemia, or CAD, nor were the apoB mutations associated with elevated lipid levels in family members. The surprising result that only two mutations of apoB in the receptor-binding domain (Arg 3500 Gln and Arg 3531 Cys) were associated with defective LDL binding, hypercholesterolemia, or CAD is in stark contrast with familial hypercholesterolemia, where nearly 150 mutations of the LDL receptor have been described that disrupt its function. This study strongly suggests that a limited number of mutations of apoB markedly influence LDL binding to its receptor.

Adult↗
PubMed1997

Mucus and H. pylori.

A continuous, adherent mucus gel layer with mucosal bicarbonate secretion is the initial protective barrier in the stomach and duodenum against erosion by the gastric juice. H. pylori resides within the adherent mucus gel layer close to the epithelial surface. The barrier function of the mucus layer in vivo depends on (i) its thickness, and (ii) its gel structure, a property which is linearly dependent on the polymeric mucin content. We have shown in vivo that H. pylori colonisation alone did not decrease the thickness of the adherent gastric mucus barrier, although there was a mean 20% decrease in mucus thickness in those H. pylori positive subjects with underlying gastric atrophy. There was, however, a significant mean 18% reduction in the gel-forming polymeric mucin content of mucus from H. pylori subjects, independent of underlying atrophy. Studies in vitro suggest this loss of gel structure might arise from a H. pylori mediated, high local pH generated by urease activity rather than by proteolysis. This study shows that H. pylori infection alone does not compromise the overall integrity of the mucus barrier in vivo. However, in the immediate environment of the organism there appears to be a localised loss of mucus gel structure. The mucus barrier is compromised if H. pylori associated gastric atrophy or peptic ulceration follows.

Animals↗
PubMed1996

Characterization of pig colonic mucins.

Pig colonic mucins isolated from the adherent mucus gel in the presence of proteinase inhibitors were solubilized by homogenization and the component mucins fractionated by CsC1 density-gradient centrifugation. Polymeric and reduced pig colonic mucin were both largely excluded on Sepharose CL-2B, papain-digested colonic mucin was included. The M(r) values of polymeric, reduced and digested mucins were 5.5 x 10(6), 2.1 x 10(6) and 0.6 x 10(6) respectively. This suggests that pig colonic mucin is comprised of 2-3 subunits, each subunit containing 3-4 glycosylated regions. The intrinsic viscosities of polymeric, reduced and digested mucin were 240 ml.g-1, 100 ml.g-1 and 20 ml.g-1 respectively. Polymeric pig colonic mucin comprised 16% protein per mg of glycoprotein and was rich in serine, threonine and proline (43% of total amino acids). There were approx. 150 disulphide bridges and 53 free thiol groups per mucin polymer. A seventh of the protein content was lost on reduction. This protein was particularly rich in proline and the hydrophobic amino acids. Papain-digested pig colonic mucin contained 11% protein per mg of glycoprotein and was rich in serine, threonine, glutamate and aspartate. All types of amino acids with the exception of aspartate were lost on digestion. The amino acid analysis of the proteolytically digested regions of pig colonic mucin are markedly different to the tandem repeat regions of the human mucin genes shown to be expressed in the colon.

Amino Acids↗
PubMed1996

Defined mutants of Proteus mirabilis lacking flagella cause ascending urinary tract infection in mice.

A clinical isolate of Proteus mirabilis (Pr 990) and an isogenic non-flagellate allelic replacement mutant (Pr M9) were tested for their ability to cause infection in the ascending mouse model of urinary tract infection. Wild-type Pr 990 differentiates into swarmer cells in brain-heart infusion broth. Pr M9 neither has flagella nor does it apparently differentiate into swarmer cells after subculturing. The infectivity of both strains from an initial culture and the sixth subculture was assessed in the ascending urinary tract infection mouse model. Infection was ascertained by determining colony forming units from kidney and bladder homogenates from individual mice 7 days after inoculation. In all cases the nonflagellate mutant Pr M9 was at least as infective as Pr 990. Using bacteria from the first culture, Pr M9 infected 61.5% and Pr 990 infected 45.5% of mice tested. The levels of viable counts were similar between the Pr M9 and the Pr 990 infections. Using bacteria from the sixth subculture, Pr M9 infected 75% and Pr 990 infected 76.5% of mice tested. Again viable counts were similar. Pr 990 increased in infectivity from the first to the sixth subculture, whereas Pr M9 did not, but this may be a reflection of the high initial rate of infectivity with first culture Pr M9. These results suggest that neither flagella nor swarmer cells are required for P. mirabilis infectivity in ascending urinary tract infections in mice.

Alleles↗
PubMed1996

The post anesthesia care unit: unique contribution, unique risk.

The environment in the postanesthesia care unit (PACU) is unique in the modern hospital. It was born of necessity and continues of necessity. The modern PACU has evolved from a simple room designed to house a single patient and a nurse to a modern, bustling room of great proportions. Today's PACU is an open ward, probably the only one left in the modern hospital, and contains many immunocompromised patients, including pediatric patients; knowledge of the patient's medical history may be sketchy or brief. Patients undergo cough-inducing procedures and exhale waste anesthesia gases. The PACU has a high ratio of health care workers (HCWs) to patients. HCWs, often in their childbearing years, function in close proximity to the patient's face. These environmental conditions coupled with the epidemic proportions of tuberculosis in the United States, the increase in incidence of hepatitis C virus, the consequences of human immunodeficiency virus, and the possible adverse effects of waste anesthesia gases result in a milieu that is a risk to both patients and HCWs that cannot be managed with air exchange controls alone. This article reviews the historical contribution of the PACU and the factors in the PACU environment that increase the vulnerability of HCWs and patients to respiratory diseases, bloodborne pathogens, and adverse effects of waste anesthetic gases.

Health Facility Environment↗
PubMed1996

The identification, cloning and mutagenesis of a genetic locus required for lipopolysaccharide biosynthesis in Bordetella pertussis.

Bordetella pertussis lipopolysaccharide (LPS) is biologically active, being both toxic and immunogenic. Using transposon mutagenesis we have identified a genetic locus required for the biosynthesis of LPS in B. pertussis, which has been cloned and sequenced. We have also identified equivalent loci in Bordetella bronchiseptica and Bordetella parapertussis and cloned part of it from B. parapertussis. The amino acid sequences derived from most of the genes present in the sequenced B. pertussis locus are similar to proteins required for the biosynthesis of LPS and other complex polysaccharides from a variety of bacteria. The genes are in a unique arrangement in the locus. Several of the genes identified are similar to genes previously shown to play specific roles in LPS O-antigen biosynthesis. In particular, the amino acid sequence derived from one of the genes is similar to the enzyme encoded by rfbP from Salmonella enterica, which catalyses the transfer of galactose to the undecaprenol phosphate antigen carrier lipid as the first step in building oligosaccharide O-antigen units, which are subsequently assembled to form polymerized O-antigen structures. Defined mutation of this gene in the B. pertussis chromosome results in the inability to express band A LPS, possibly suggesting that the trisaccharide comprising band A is a single O-antigen-like structure and that B. pertussis LPS is similar to semi-rough LPS seen in some mutants of enteric bacteria.

Amino Acid Sequence↗
PubMed1996

Leaf permease1 gene of maize is required for chloroplast development.

Adjacent bundle sheath and mesophyll cells cooperate for carbon fixation in the leaves of C4 plants. Mutants with compromised plastid development should reveal the degree to which this cooperation is obligatory, because one can assay whether mesophyll cells with defective bundle sheath neighbors retain C4 characteristics or revert to C3 photosynthesis. The leaf permease1-mutable1 (lpe1-m1) mutant of maize exhibits disrupted chloroplast ultrastructure, preferentially affecting bundle sheath choroplasts under lower light. Despite the disrupted ultrastructure, the metabolic cooperation of bundle sheath and mesophyll cells for C4 photosynthesis remains intact. To investigate this novel mutation, the Activator transposon-tagged allele and cDNAs corresponding to the Lpe1 mRNA from wild-type plants were cloned. The Lpe1 gene encodes a polypeptide with significant similarity to microbial pyrimidine and purine transport proteins. An analysis of revertant sectors generated by Activator excision suggests that the Lpe1 gene product is cell autonomous and can be absent up to the last cell divisions in the leaf primordium without blocking bundle sheath chloroplast development.

Amino Acid Sequence↗
PubMed1996

Home health visits using a cable television network: user satisfaction.

There are about 1.5 million home patients who receive home health care (nurses visiting patients in their homes) in the US each year. In a significant proportion of these visits, hands-on care is not needed. Rather, the nurse needs to verify compliance with medication regimes, assess mental or emotional status, or check blood sugar levels, blood pressure and the like. Many of these activities might be handled by a nursing visit using interactive video to the patient's home, saving the nurse's time wasted in driving, finding parking, etc. A system for delivering home health care using interactive video has been piloted in the state of Kansas. Using the local cable television infrastructure for audio and video transmission, this system permits a nurse to see patients in their homes for a fraction of the cost of an on-site visit. This new method of delivering home health care is being evaluated with an ongoing study of utilization and user satisfaction. We conducted a prospective survey administered to home health nurses (n = 2) and homebound patients (n = 3) using a cable TV-mediated interactive video system, to assess utilization and user satisfaction with televideo-mediated home health care visits. One hundred and eighty-one patient questionnaires and 193 nurses questionnaires were completed. The average length of a visit was 15 minutes (range 1-91). All mean scores tabulated for the questions indicated strong nurse and patient satisfaction with the system. Participating nurses and clients were satisfied with the televideo encounters. The mean score for all questions was better than neutral. Recognizing that this was a pilot study, hampered by small numbers and subject to the inherent biases of a single institution study, the results support further investigation and implementation of this modality for home health care.

Aged↗
PubMed1996

Arthroscopic release for chronic, refractory adhesive capsulitis of the shoulder.

Idiopathic adhesive capsulitis usually responds to gentle physical therapy or, if that fails, to closed manipulation with the patient under anesthesia. In some patients, however, loss of motion may be refractory to either of these treatments and an operative release may be indicated. We are reporting on the technique and results of arthroscopic capsular release as a new alternative for the management of such patients. During a three-year period, we managed twenty-three patients who had idiopathic adhesive capsulitis that had failed to respond to physical therapy or closed manipulation. These patients had an arthroscopic anterior capsular release and received forty-eight hours of intensive physical therapy as inpatients. During the physical therapy, the patients received an interscalene regional analgesic with use of repeated nerve blocks or with a continuous infusion through an interscalene catheter. This was followed by a supervised outpatient physical-therapy program. Six patients also had an arthroscopic acromioplasty for the treatment of impingement. There were no complications related to any of the procedures. At a mean of thirty-nine months (range, twenty-four to sixty-four months) after the arthroscopic procedure, the improvement in the score of Constant and Murley averaged 48 points (range, 13 to 77 points). The mean improvement in motion was 49 degrees (range, 0 to 105 degrees) for flexion; 42 degrees (range, 10 to 80 degrees) and 53 degrees (range, 0 to 100 degrees) for external rotation in adduction and abduction, respectively; and eight spinous-process levels (range, three to fourteen levels) and 33 degrees (range, 30 to 60 degrees) for internal rotation in adduction and abduction, respectively. These gains in motion were all significant (p < 0.01) compared with the preoperative values and were within a mean of 7 degrees of the values for the contralateral, normal shoulder. We concluded that, in patients who have loss of motion that is refractory to closed manipulation, arthroscopic capsular release improves motion reliably with little operative morbidity.

Adult↗