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Biomedical subjects

M Larsen

Publications and source records attributed to M Larsen.

At least 145 records · Page 8Linked to original sources
PubMed1992

Development of immunity to Ostertagia ostertagi (Trichostrongylidae: Nematoda) in pastured young cattle.

This experiment comprised 3 groups of calves, (+P2), (-P2) and (-P1), which all started their first grazing season as parasite-free calves. The (+P2)- and (-P2)-group grazed 2 seasons. In the first season the (-P2)-group of calves was grazing a pasture with no detectable trichostrongyles and treated with anthelmintics every second week. The untreated (+P2)-group grazed an Ostertagia ostertagi contaminated pasture. During the second grazing season these 2 original groups grazed together with a new group of first-year grazing calves (-P1) on paddocks infected with O. ostertagi. Parasitological analyses showed that (+P2)-group had negligible egg excretions in the second year in comparison with (-P2) and (-P1). This indicated, that the egg output may be regulated through acquired immunity. The difference in egg excretions was not reflected in the serum pepsinogen levels, which were only slightly elevated for all groups in the second year. Post mortem examination at the end of the experiment showed that only the (-P1)-group harboured relatively high numbers of worms in the abomasa at that time. Antibodies of 3 immunoglobulin classes were investigated: IgA, IgG1 and IgG2. The IgA and IgG1 responses correlated with the presence of developing and adult worms in the abomasa and they remained elevated in the (+P2)-group throughout the experiment, perhaps indicating an involvement of these antibodies in a protective immune response. In the (-P2)-group the IgA and IgG1 showed fast and sharp rises during the second season that most likely were age-related and as such a result of maturation of the immune system. The role of IgG2 is unclear as the IgG2 response was weak in all groups of calves and difficult to relate to the parasitological data.

Aging↗
PubMed1991

[Infrared tympanic thermography. A comparison of body temperature measured rectally and from the tympanic membrane].

Infrared tympanic thermography is a new method of measuring body temperature. We compared body temperature measured in the rectum and in the ear in 25 patients. The results reveal a difference of average +/- 0.3 degree C. We also measured the time used to perform the above procedures. We found that the preparation and completion procedures took on average two minutes and 50 seconds when the body temperature was measured in the rectum. Taking the temperature in the ear took on average 42 seconds. We found that this new method was an accurate and quick method to measure body temperature.

Body Temperature↗
PubMed1991

[Prevention of perinatal hepatitis B virus transmission. Epidemiology and cost/efficacy ratio in the Paris region].

The HBs antigen (AgHBs) was detected in 152 out of 6605 (2.3 percent) pregnant women who attended four representative maternity clinics in the Paris region. In 98 percent of the cases this finding reflected chronic hepatitis B virus infection. Among women born outside France (47 percent of the women tested, 79 percent of the AgHBs positive women), the relative risk was 6 for Asiatics, 5.5 for Africans and 4 for French women born in overseas departments or territories. Whatever the women's geographical origin, studies of their medical history revealed no significant difference between AgHBs positivity and AgHBs negativity. Overcrowding and multiparity correlated globally with the presence of AgHBs, but this correlation was absent in French women born in France. In non-African and non-Asiatic women detection guided by medical and socio-familial criteria would not be efficacious. The authors recommend systematic detection of AgHBs in pregnant women and estimate at about 180,000 french francs the cost of prevention for each case evolving toward the vital complications of chronic hepatitis B virus infection, an outcome which in the long term may affect 600 individuals born each year and who had contracted the infection during the perinatal period.

Adult↗
PubMed1991

Longterm remission of multiple brain metastases with tamoxifen.

A case of multiple brain metastases from breast carcinoma treated with tamoxifen is described. She remained in remission for 58 months and is still alive after 82+ months of hormone therapy. The case indicates that hormonal treatment may be very effective in the management of brain metastases from breast carcinoma.

Activities of Daily Living↗
PubMed1991

Differential spectrofluorometry in the human vitreous: blood-retina barrier permeability to fluorescein and fluorescein glucuronide.

A method is described for the separate quantitation of fluorescein and fluorescein glucuronide in the vitreous by differential spectrofluorometry. An ocular fluorometer was equipped with monochromatic laser excitation at two rapidly interchangeable wavelengths. The data analysis accounts for absorption of light in the cornea, lens, and extrinsic ocular fluorophores. Examination of seven patients with insulin-dependent diabetes and different degrees of diabetic retinopathy demonstrated that both fluorescein and fluorescein glucuronide enter the eye through the blood-retina barrier. The mean ratio between the permeabilities of fluorescein glucuronide and fluorescein was 0.9 (range, 0.3-1.9). Thus, differences in the molecular size and lipid solubility of the two substances appear to be of little or no importance for their inward penetration of the barrier. No association was found between the relative permeability and the degree of retinopathy.

Adult↗
PubMed1991

Determination of spatial coordinates in ocular fluorometry.

A method has been developed for the determination of spatial coordinates of ocular fluorescence measurements made by a non-contact-lens type of fluorometer (Fluorotron, Coherent Inc., Palo Alto, Calif., USA). The method is based upon a mathematical model of the instrument and the eye. The model is adapted to the individual eye by the extraction of information from the fluorescence scan and the use of keratometry to determine the radius of curvature of the anterior corneal surface. The validity of the model was examined by comparison of the ocular axial length as measured by fluorometry vs ultrasonometry in 26 eyes of healthy human subjects. The results of fluorometry differed from those of ultrasonometry by less than +/- 2%.

Adult↗
PubMed1991

Lens fluorometry: light-attenuation effects and estimation of total lens transmittance.

Front-face fluorometry of the axial fluorescence profile of the lens is influenced by attenuation of light along the optical pathways leading to and from the detection volume. The resulting distortion is evident when the curve is compared with the intrinsic profile that can be recorded by direct measurement on the transected lens. Assuming that attenuation of light by scatter and absorption is proportional to fluorescence, the intrinsic profile can be reconstructed from the non-invasive fluorescence profile. The calculations involve the deduction of total lens transmittance and fluorescence-related absorptivity, parameters that provide essential information about the optical quality of the lens. The method was applied to human lens fluorometry in vivo and in vitro (excitation 430-490 nm, fluorescence 530-630 nm). Even the most anterior lens fluorescence measurements were found to be markedly affected by attenuation of light in the lens. Lens transmittance estimates agreed within +/- 12% with direct measurements of lens transmittance. The differences were due in part to inter-individual variations in the shape of the intrinsic fluorescence profile of the lens.

Absorption↗
PubMed1991

Ability of the fungus Pleurotus pulmonarius to immobilise preparasitic nematode larvae.

In vitro experiments showed that the oyster mushroom Pleurotus pulmonarius exerts a strong immobilising effect on preinfective larvae of the animal parasitic nematodes Ostertagia ostertagi, Cooperia oncophora, Oesophagostomum quadrispinulatum and Cyathostoma species. Infective stages of the same species seemed less vulnerable to fungal attack, possibly because they are protected by their outer cuticle.

Animals↗
PubMed1991

In vitro stress selection of nematophagous fungi for biocontrol of parasitic nematodes in ruminants.

Laboratory experiments were designed to select nematophagous fungi that were able to survive in vitro conditions simulating passage through the gastro-intestinal tract of cattle. All of the tests were conducted at 39 degrees C. In a primary stress selection step in diluted rumen fluid, 21 isolates were obtained. Each of the primary stress selected isolates was tested in synthetic saliva, rumen fluid simulating the activity in the rumen, rumen fluid followed by pepsin-hydrochloric acid treatment simulating the additional effect of ruminal and abomasal activity, pepsin-hydrochloric acid solution simulating conditions in the abomasum and finally in a trypsin solution as an example of enzyme activity in the gut. The effect of the rumen fluid alone, or rumen fluid followed by pepsin-hydrochloric acid treatment, were responsible for the reduction in surviving fungal isolates. Only six of thirteen isolates belonging to the genus Arthrobotrys survived while seven of eight isolates of the genus Duddingtonia survived. Fourteen isolates were tested for their predatory capacity in a dung pat bioassay. Fungi of the genera Arthrobotrys and Duddingtonia reduced the development of Ostertagia ostertagi third stage larvae by approximately 75% and 96% respectively compared to the number of larvae that developed from fungus-free control pats.

Animals↗
PubMed1991

Long-term results of extracapsular cataract extraction with posterior chamber lens implantation: sodium hyaluronate 1% vs hydroxypropyl methylcellulose 2%.

We investigated the frequency of surgical complications and the long-term outcome in terms of visual acuity, intraocular pressure and post-operative complications in 206 extracapsular cataract extraction procedures with posterior chamber lens implantation using either sodium hyaluronate 1% (Healon) or hydroxypropyl-methylcellulose 2% over a follow-up period of 12 months. We found no significant difference in the results of using either of the two viscoelastic agents.

Adult↗
PubMed1991

Blood-retina barrier permeability in diabetes during acute ACE-inhibition.

We assessed the acute effect of ACE-inhibition (captopril) on blood-retina barrier (BRB) permeability in 10 hypertensive insulin-dependent diabetic patients with background retinopathy in a double-masked placebo controlled cross-over study. All patients underwent ophthalmological examination, fundus photography, fluorescein angiography, vitreous fluorometry, and continuous blood pressure recording within 3 h of the drug/placebo administration. The decrease in mean arterial blood pressure, from placebo treatment 149/92 +/- 17/7 to captopril treatment 132/83 +/- 14/7 mmHg (mean +/- SD), P less than 0.01 was not accompanied by a significant decrease in BRB permeability, which was 2.51 (1.24-9.15) with placebo and 3.02 (1.25-13.93).10(-7) cm/s during captopril treatment (geometric mean and-range), NS. Our study suggests that abnormal leakage through the BRB in hypertensive insulin-dependent diabetic patients with background retinopathy is caused predominantly by structural changes in the retinal vessels whereas hydrostatic forces play a minor role.

Adult↗
PubMed1991

[The perinatal transmission of the hepatitis B virus in the Paris area].

HBsAg was detected in 152 pregnant women among 6,605 (2.3%) screened in the prenatal clinics of four hospitals representative of the Paris metropolitan area. In 98% of cases, HBsAg positivity indicated chronic HBV carrier status. Among patients born out of continental France (47% of screened women, 79% of positive women) relative risk of chronic infection was 6 in Asians, 5.5 in Africans, and 4 in French women born in non-continental France. No significant difference in medical history was seen between HBsAg-positive and HBsAg-negative patients, in any of the birthplace groups. In women born out of continental France, number of children and crowding in the home were correlated with HBsAg-positivity; these correlations were not found in French women born in continental France. In non-African, non-Asian women, screening on the basis of medical, social and familial criteria (simulated in this study) would not be effective. Routine screening for HBsAg in pregnancy is advocated. The cost of the prevention of each case of perinatally acquired chronic HBV infection by routine screening followed by prophylactic treatment of a risk neonates was estimated at 180,000 French Francs (35,000 dollars). This approach is the only means of preventing the long-term life-threatening complications of chronic HBV infection in the 600 neonates born each year in France to HBsAg-positive mothers.

Africa↗
PubMed1991

[Perinatal transmission of the hepatitis B virus in Paris region].

HBsAg was detected in 152 pregnant women among 6,605 (2.3%) screened in the prenatal clinics of four hospitals representative of the Paris metropolitan area. In 98% of cases, HBsAg positivity indicated chronic HBV carrier status. Among patients born out of continental France (47% of screened women, 79% of positive women) relative risk of chronic infection was 6 in Asians, 5.5 in Africans, and 4 in French women born in non-continental France. No significant difference in medical history was seen between HBsAg-positive and HBsAg-negative patients, in any of the birthplace groups. In women born out of continental France, number of children and crowding of the home were correlated with HBsAg-positivity; these correlations were not found in French women born in continental France. In non-African, non-Asian women, screening on the basis of medical, social and familial criteria (simulated in this study) would not be effective. Routine screening for HBsAg in pregnancy is advocated. The cost of the prevention of each case of perinatally acquired chronic HBV infection by routine screening followed by prophylactic treatment of at risk neonates was estimated at 180,000 French Francs (35,000 dollars). This approach is the only means of preventing the long-term life-threatening complications of chronic HBV infection in the 600 neonates born each year in France to HBsAg-positive mothers.

Female↗
PubMed1990

Protective effect of captopril on the blood-retina barrier in normotensive insulin-dependent diabetic patients with nephropathy and background retinopathy.

The effect of 18 months' inhibition of angiotensin-converting enzyme by captopril on the leakage of fluorescein through the blood-retina barrier was examined in a prospective, randomized control study of 20 normotensive insulin-dependent diabetic patients with nephropathy and background retinopathy. After 18 months, 15 patients remained in the study. Fluorescein leakage remained nearly unchanged in the captopril-treated group, being 4.1 +/- 4.1 (mean +/- SD) x 10(-7) cm/s at baseline and 4.2 +/- 4.1 x 10(-7) cm/s after 18 months' treatment. The permeability increased significantly (P less than 0.01) from 3.3 +/- 2.2 x 10(-7) cm/s to 5.6 +/- 3.5 x 10(-7) cm/s at 18 months in the control group. Arterial blood pressure was nearly constant in both groups throughout the study. The results indicate that angiotensin-converting enzyme inhibition with captopril can arrest or delay a progressive breakdown of the blood-retina barrier in normotensive insulin-dependent diabetic patients with nephropathy and background retinopathy.

Adult↗
PubMed1990

Effect of one year continuous subcutaneous infusion of a somatostatin analogue, octreotide, on early retinopathy, metabolic control and thyroid function in Type I (insulin-dependent) diabetes mellitus.

Growth hormone is assumed to be involved in the development of diabetic retinopathy. In a randomized study we evaluated the possible effects of one year treatment with a somatostatin (SRIH) analogue, octreotide, on early retinopathy and on metabolism in Type I (insulin-dependent) diabetes mellitus. Eleven patients were allocated to treatment with a continuous sc infusion of 400 micrograms octreotide per day and 9 served as controls. Only 7 patients from each group completed the study. Three octreotide-treated patients left the study owing to severe diarrhea. The subjects were evaluated at entry, after 2, 6 and 12 months treatment, and 2 months after withdrawal. Octreotide induced a decrease in GH secretion, expressed as the area under the 24 h serum GH profiles (p less than 0.05), and of the serum levels of IGF-I (p less than 0.05). The entire decline in GH levels occurred during the daytime, whereas the nocturnal levels were unaffected. Retinopathy, as assessed by determination of the blood retina barrier permeability, by colour fundus photography, and flurescein angiography was unchanged in both groups. Apart from a decline in insulin requirements, octreotide had no major effect on glycemic control, but induced a mild transient pituitary hypothyroidism, not clinically relevant. We conclude that treatment with octreotide for one year has modest effects on GH, IGF-I, and glucose metabolism, but has no significant effect on early retinopathy in Type I (insulin-dependent) diabetes.

Adult↗
PubMed1990

Fitting numerical solutions of differential equations to experimental data: a case study and some general remarks.

A simple and efficient algorithm for least-squares estimation of the parameters of a numerically solved diffusion model is presented. The algorithm has been specially developed for the analysis of data obtained by vitreous fluorophotometry (a method in clinical eye research), but it has several straightforward generalizations which are also outlined in the paper.

Algorithms↗