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Biomedical subjects

D P Stevens

Publications and source records attributed to D P Stevens.

At least 19 recordsLinked to original sources
PubMed1991

Elastase is a constituent product of T cells.

Proteases produced by immune cells have been found to be important components of the immune response to antigen. A protease previously unrecognized as a specific T cell product has been identified which has the gene sequence, serologic crossreactivity, and enzymatic specificity of elastase. T cell elastase, found in combination with the natural elastase inhibitor alpha 1-antitrypsin (alpha 1-protease inhibitor, alpha 1-PI), is produced by both CD4+ and CD8+ T lymphocytes, and is found both in a membrane-bound and in a soluble form in murine T cell lines.

Amino Acid Sequence↗
PubMed1989

Regulation of oxygen concentration delivered to infants via nasal cannulas.

The administration of oxygen to infants via nasal cannulas is now a common practice in neonatal units although the inspired oxygen concentration reaching the patient's airway is unknown. We measured the hypopharyngeal oxygen concentration in 10 infants who were receiving oxygen via nasal cannulas and assessed the impact of changes in the flow rate and inspired oxygen concentration. Weaning these infants by reducing the flow rate, even if changes are slight, produces clinically important changes in the oxygen concentration reaching the airway. Such changes are poorly tolerated by infants with chronic lung disease. Changing the flow rate and inspired oxygen concentration, rather than the flow rate alone, provides greater precision and is likely to avoid excessive and abrupt changes in the oxygen concentration reaching the airway.

Administration, Intranasal↗
PubMed1987

Cypermethrin pour-on for the control of ticks (Ixodes ricinus) on sheep.

Trials were carried out on 11 farms to assess the effectiveness of 2.5 per cent w/v cypermethrin pour-on for the control of ticks on sheep. Treatment at the rate of 5 ml/10 kg bodyweight gave 92 per cent control of ticks on ewes for up to nine weeks and 88 per cent control on lambs for up to eight weeks.

Administration, Topical↗
PubMed1979

Ultrastructural observations on giardiasis in a mouse model. II. Endosymbiosis and organelle distribution in Giardia muris and Giardia lamblia.

Ultrastructural observations of Giardia muris in a mouse model revealed endosymbiotic microbes not previously reported in Giardia. Endosymbionts 240--360 nm wide, 600--1,400 nm long, and with an internal structure similar to that of bacilli were not seen entering Giardia but were found and appeared to divide within Giardia. No evidence was found of digestion of the endosymbionts by the giardia host in either the trophozoite or the cyst form. Endosymbionts were concentrated centrally around the nuclear area and were uncommon in peripheral feeding regions. The same cellular organelles seen in G. muris were found in Giardia lamblia from human jejunal biopsy material, but no endosymbionts were identified in G. lamblia trophozoites from the seven patients examined. Endosymbionts within Giardia may be found to alter trophozoite pathogenicity, metabolism, range of infectivity, antigenic surface characteristics, and host specificity, as they do in other protozoa.

Animals↗
PubMed1979

Ultrastructural observations on giardiasis in a murine model. I. Intestinal distribution, attachment, and relationship to the immune system of Giardia muris.

Infected immunocompetent mice were studied prospectively in a well-described murine model system with the use of ultrastructural techniques to establish normal distribution of Giardia muris trophozoites, their relationships to intestinal mucosa, particularly Peyer's patches, and structural indications of the normal reaction of intestine and intestinal immune organs. Trophozoites colonized the proximal 25% of the intestine, adhered to microvilli of columnar cells near the bases of villi, wedged into furrows in the epithelial surface, or lodged in mucus within the unstirred layer. Density of trophozoite colonization of the jejunal epithelium correlated with stool cyst excretion. Over Peyer's patches, Giardia adhered to columnar cells and not to M-cells, which transport soluble antigens and particulate material from the lumen into the lymphoid system. Giardia entered intestinal lymphoid structures by incursions through defects in the lymphoid follicle epithelial barrier. During clearance of parasites, lymphocytes crossed the epithelium and attached to Giardia in the lumen. Giardia produced no apparent ultrastructural damage in normal mice but elicited a previously undescribed intraluminal cellular immune response during clearance by the host.

Animals↗
PubMed1977

Factors influencing small bowel changes in dermatitis herpetiformis.

Factors influencing small bowel morphology in dermatitis herpetiformis (DH) were investigated by comparing patients with DH and normal small bowel biopsies to patients with DH and abnormal small bowel biopsies. The mean age of 18 patients with morphological changes in small bowel (38 years) was significantly lower (P less than 0-001) than the mean age of nine patients with normal bowel mucosa (60 years). HLA typing confirmed the high frequency of HLA-B8 in DH (64%) but HLA-B8 was unrelated to the presence or severity of small bowel lesions. Four patients had diarrhoea with progressive weight loss or abdominal cramps subsequently responsive to gluten withdrawal. In this subgroup serum levels of IgG and IgM were significantly lower than in patients with normal small bowel mucosa. Small bowel involvement appeared to be independent of the duration and severity of skin disease, and the deposition of immunoglobulin and complement (C3) in the dermal papillae of skin adjacent to skin lesions.

Adult↗
PubMed1977

What happens when hospitalized patients see their own records.

The effect of giving hospitalized medical patients access to their problem-oriented hospital records was investigated. Twenty-five subjects were given free access to their records while 25 other subjects served as controls. Few of the open record group actively sought and studied their records; most elected to see them only as part of routine ward rounds; and one objected to seeing the record at all. Taking the experimental group as a whole, there was no measurable effect of seeing the record on the subjects' ability to list their diagnoses or medications, their self-assessment of depression, anxiety or contentment, or their attitudes toward selected components of the health care system. On the other hand, in individual instances access to the hospital record seemed to facilitate communication and provide an opportunity for hospital inpatients to monitor objectively their hospital course.

Australia↗
PubMed1976

Carcinoembryonic antigen (CEA), smoking, and cancer in a longitudinal population study.

In 1969, the prevalence of raised levels (5 ng/ml of serum) of carcinoembryonic antigen (CEA) was estimated in 2372 persons aged 40 years and over in Busselton, Western Australia. There were raised levels of CEA in 73 subjects (3%). The prevalence increased progressively with age in both non-smokers and smokers with a higher rate of prevalence at all ages in smokers, and a peak of 11% in smokers aged 65--74 years. Among non-smokers, the prevalence was similar in both men and women (1%), in smokers there was a stepwise rise in prevalence with increasing tobacco consumption. Subsequently, levels of CEA of 5 ng/ml or over tended to disappear from the sera in a greater proportion of the non/exsmokers than of smokers. In the following five years, "CEA-associated" cancer occurred in nine of 73 subjects (13%) with raised levels of CEA compared with 25 in 2299 (1%) in those with normal CEA levels. This association was independent of the confounding effects of age, sex, and smoking habit. The five year data on 2372 subjects have confirmed that CEA screening of healthy Busselton subjects has identified a group at future risk of developing "CEA-associated" cancers, in addition to drawing attention to the presence of existing cancers.

Adult↗
PubMed1976

Suppression of giardiasis during the intestinal phase of trichinosis in the mouse.

The interaction of the intestinal phases of Giardia muris and Trichinella spiralis was investigated in Swiss albino mice. Intraoesophageal inoculation of G. muris cysts seven days before, or seven days after, similar inoculation of T. spiralis larvae resulted in significant reduction in the numbers of Giardia trophozoites in small bowel and Giardia cysts in stools. This effect was not observed when G. muris cysts were administered after resolution of the intestinal phase of trichinosis. Giardiasis had no effect on trichinosis as assessed by numbers of adult worms in small bowel and larvae in skeletal muscles. Studies of small bowel morphology showed that the intestinal phase of trichinosis was associated with increased numbers of inflammatory cells in the lamina propria, a significant increase in Paneth cells in crypts, and a marked reduction in the villus:crypt ratio of jejunum. These observations suggest that the intestinal phase of trichinosis induced environmental changes in small bowel, perhaps related to inflammation, which resulted in suppression of proliferation of Giardia trophozoites.

Animals↗
PubMed1976

Symptomatic hepatic disease in cystic fibrosis: incidence, course, and outcome of portal systemic hunting.

Fifteen (2.2%) of 693 patients with cystic fibrosis seen over an 18-year period developed clinical hepatic disease. In 13 patients all symptoms were secondary to portal hypertension. Ten had hypersplenism and 6 had variceal bleeding, including 3 who developed both conditions. All 5 patients who survived the initial episode of gastrointestinal bleeding underwent portal systemic shunting. A shunting procedure also was performed on 1 patients with hypersplenism but no variceal bleeding. No subsequent deterioration of intellectual function occurred in either the shunted or unshunted patients. Only 1 of the shunted patients showed progression of hepatic disease after surgery. These results suggest that portal systemic shunting is useful in the treatment of bleeding esophageal varices in cystic fibrosis. A sweat test to rule out cystic fibrosis should be included in the evaluation of any teenage or young adult patient with unexplained portal hypertension.

Adolescent↗
PubMed1976

Giardiasis in the mouse: an animal model.

An animal model for giardiasis was developed using Giardia muris in Swiss albino mice. Intraesophageal inoculation of G. muris cysts caused a reproducible pattern of infection, with trophozoite and cyst counts reaching a maximum on days 5 to 14 after cyst inoculation and thereafter showing a progressive decline. Spontaneous resolution of infection occurred in most mice after 21 to 28 days. When compared to uninfected controls, Giardia-infected mice had significant impairment of weight gain and a significant reduction in the villus to crypt ratio of jejunal mucosa. Although maximal trophozoite and cyst counts were independent of the size of the cyst inoculum, those mice receiving inoculations of larger numbers of cysts showed earlier attainment of maximal counts, greater impariment of weight gain, and earlier and more severe small bowel changes than mice receiving inoculations of smaller numbers of cysts. This model offers unique opportunities for study of this poorly understood gastrointestinal parasite.

Animals↗