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Biomedical subjects

T Karlsson

Publications and source records attributed to T Karlsson.

12 recordsLinked to original sources
PubMed1992

Neuro-effector characteristics of sweat glands in the human hand activated by irregular stimuli.

Intraneural electrical stimulation of cutaneous fascicles in the median nerve was performed in 24 normal subjects and the effects on sweating within the innervation zone were monitored as changes of skin resistance and water vapour partial pressure (wvpp). The aims were: (1) to investigate the response variability between repeated stimulation sequences in the same skin site and between different sites and (2) to compare quantitative effects of regular and irregular stimulation on skin resistance and wvpp. Regional axillary anaesthesia of the brachial plexus eliminated spontaneous and reflex sympathetic activity. With repeated irregular stimulation sequences skin resistance responses from the same skin site varied only slightly between trials. Differences between response curves from two skin sites in the same subject or from different subjects were also small but significantly greater (P < 0.01) than differences between responses to repeated stimulation in the same site. Irregular stimulation with average frequencies of 0.49 Hz and 3.51 Hz gave greater resistance responses than if the same number of stimuli were delivered regularly (P < 0.01). The difference was most pronounced at 0.49 Hz. At an average frequency of 0.49 Hz the stimulation usually evoked no changes of wvpp whereas an average frequency of 3.51 Hz caused an increase of wvpp which was greater with irregular than with regular stimulation in all subjects. We conclude that: (1) sweat responses to sudomotor nerve traffic vary slightly due to local factors in the skin or the terminal nerve endings and (2) irregular sudomotor nerve traffic evokes more sweat than if the same impulses occur regularly.

Adult↗
PubMed1992

Non-linearity of skin resistance response to intraneural electrical stimulation of sudomotor nerves.

Intraneural electrical stimuli (0.3 mA, 0.2 ms) were delivered via a tungsten microelectrode inserted into a cutaneous fascicle in the median nerve at the wrist in 16 normal subjects, and the effects on the sweat glands within the innervation zone were recorded as changes of skin resistance. In order to examine the relationship between the skin resistance level and the amplitude of transient resistance responses, trains of high frequency stimulation were used to reduce the skin resistance level and then transient resistance responses were evoked by single stimuli at 0.1 Hz. Regional anaesthesia of the brachial plexus in the axilla eliminated spontaneous sympathetic activity and reflex effects. At high skin resistance levels response amplitudes to single stimuli were low but they increased successively to a maximum at intermediate levels and then decreased again at low resistance levels. Repeated stimulation sequences evoked qualitatively similar response curves but quantitatively both response amplitudes and skin resistance levels were slightly reduced upon repetition. We suggest that the changes of response amplitudes are due to variable resistivity of the corneal layer. The shifts of the response curves with repetition of stimulation may result from increased hydration of the corneum. It is concluded that the variability of response amplitudes to constant stimuli makes the amplitude of a skin resistance response unsuitable as an indicator of the strength of sympathetic sudomotor nerve traffic.

Adult↗
PubMed1992

The role of early surgery following myocardial infarction. European Coronary Surgery Bypass Group.

This co-operative study was a prospective randomised study to evaluate the role of coronary bypass surgery following acute myocardial infarction. The criterion for entry was an early positive exercise tolerance test. All patients who satisfied the clinical criteria of acute myocardial infarction but who were excluded had information on survival obtained after two years. A total of 4658 patients were assessed, with 3334 (71%) having a modified exercise test. This test was positive in 728 patients, of whom 598 then underwent coronary angiography. Three hundred and forty-eight patients were randomised (surgery 168, continuing medical treatment 180). At two years the survival in the medical group was 96% and in the surgical group was 93%. At five years the corresponding figures were 88% and 91%. Sub group analyses in terms of age, ejection fraction and extent of vessel disease failed to show any significant differences between those randomised to medicine or surgery. A positive exercise test early after infarction does help to delineate those more likely to require intervention, but a negative exercise test is not an indication for complacency.

Cardiac Surgical Procedures↗
PubMed1992

Postoperative follow-up of patients with colorectal carcinoma by colonoscopy.

OBJECTIVE: To find out if colonoscopy is of use in the follow-up of patients who have been operated on for colorectal carcinoma. DESIGN: Retrospective study. SETTING: Department of diagnostic radiology, university hospital. SUBJECTS: 390 consecutive patients operated on for colorectal carcinoma during the 10-year period 1981 to 1990. MAIN OUTCOME MEASURES: Number of recurrences, synchronous of metachronous tumours, and number and size of adenomas found on colonoscopy. RESULTS: Neoplastic lesions were found in 175 (45%) of the 390 patients studied. There were 14 anastomotic recurrences and 12 new primary carcinomas. At operation for recurrent tumours Dukes' A or B lesions were found in half of the 14 patients who had no symptoms, and a quarter of the 12 who had had symptoms. Those with recurrent carcinoma were younger than those without. Adenomas 1 cm in diameter or more were found in 44 patients and 104 had adenomas less than 1 cm. In addition one carcinoid was found. CONCLUSION: Colonoscopy gave a high yield of neoplastic lesions when used to follow-up patients after resection of colorectal carcinoma, particularly at six months, and resulted in half the recurrent carcinomas being diagnosed before the patients had symptoms. We recommend its use for follow-up of high risk patients, but further studies are needed to establish the optimum time intervals.

Adenoma↗
PubMed1979

Analysis of the serum IgE levels in nonimmunized rats of various strains by a radioimmunoassay.

An assay, the paper radioimmunosorbent test (PRIST) for the measurement of total serum IgE in the rat, that allows the measurement of IgE down to a level of 0.25 ng/ml, is described. With this assay it has been demonstrated that significant differences exist in normal serum IgE levels in non-immunized rats. These differences are strain-dependent, and strains may be classified as to low (less than 50 ng/ml), medium (50--300 ng/ml) or high (greater than 300 ng/ml) serum levels. The serum IgE level is not sex-dependent. Environmental factors have a pronounced influence, optimal housing conditions resulting in low and stable levels while suboptimal conditions result in high levels with great fluctuations. Hybridization experiments suggest a multigenic control, with low IgE strains having a dominating suppressor effect.

Age Factors↗
PubMed1979

A radioimmunoassay for evaluation of the IgE and IgG antibody responses in the rat.

An assay, the paper radioallergosorbent test (PRAST), for the measurement of specific serum IgE antibody in the rat is described in detail. This assay has been used, in conjunction with a modified PRAST for the determination of relative specific serum IgG antibody and the PRIST assay for total serum IgE [13], to measure specific IgE and IgG and total IgE immune responses in normal parasite infected rats immunized using various protocols. The results indicate that there is a relationship between the basic IgE level and the immune response, i.e. a rat strain with a low constitutive IgE level demonstrates a weak response whereas a high level strain reacts strongly. When PRAST and passive cutaneous anaphylaxis (PCA) were compared, using standardized IgE antibody containing sera, the results were in good agreement. However, PRAST is the preferable assay as it shows less intrinsic variation, is more sensitive than PCA, and is not influenced by high serum IgE levels in the recipient animal.

Anaphylaxis↗
PubMed1979

Relationship between serum IgE levels and anaphylactic histamine release from isolated rat mast cells.

Inbred Hooded Lister rats were immunized with egg albumin with B. pertussis vaccine used as an adjuvant. The serum levels of total IgE and IgE antibody (egg albumin specific) were determined by radioimmunoassay techniques before and after immunization. The basic level of total IgE in serum was 560 +/- 110 ng/ml. After immunization a maximal peak at day 11 of 1940 +/- 160 ng/ml was registered. Anti-egg albumin IgE antibody showed a maximum around day 13 of 75 +/- 11 units/ml. Pleural mast cells were isolated on Ficoll between day 14 and 20 after immunization. A significant negative correlation between the basic total IgE level and histamine release by antigen (egg albumin) was found and also a significant positive correlation of specific IgE antibody (determined at day 11) and histamine release. The correlation between IgE level and histamine release was slightly improved if instead the ratio of specific IgE antibody over total IgE was used.

Anaphylaxis↗
PubMed1979

Solid-phase radioimmunoassay of serum immunoglobulin A antibodies to respiratory syncytial virus and adenovirus.

A solid-phase radioimmunoassay for detecting respiratory syncytial virus and adenovirus serum immunoglobulin A (IgA) antibodies was developed. An antigen consisting of purified adenovirus type 2 hexons or a crude lysate of respiratory syncytial virus-infected cells was first adsorbed onto polystyrene beads. The coated beads were then incubated with dilutions of serum, and IgA antibodies which attached to the solid-phase virus antigen were subsequently detected with 125I-labeled anti-human alpha antibodies. The anti-human alpha antibodies used were isolated by immunosorbent chromatography from rabbit antiserum produced by immunization with IgA purified from serum of an IgA myeloma patient. A total of 46 serum specimens from 13 patients with respiratory syncytial virus infections and 10 patients with adenovirus infections were tested. Complement fixation, homologous IgG and IgM radioimmunoassay, and heterologous IgA radioimmunoassay testing were also done. Specific values higher than 10,000 cpm were often reached with convalescent serum specimens, and positive-to-negative serum binding ratios of 50 or more were frequently obtained with lower serum dilutions. IgA titers of convalescent sera were from 1,000 to 16,000, and with few exceptions a fourfold or greater rise in the IgA titer was detected in the homologous IgA radioimmunoassay.

Acute Disease↗
PubMed1977

Prevalence of Eimeria acervulina, Eimeria necatrix, Eimeria brunetti and Eimeria tenella in Georgia (USA) as demonstrated by immunity challenge techniques.

Eimeria acervulina, E. necatrix, E. brunetti and E. tenella were found to be widely distributed in north-east Georgia. 2. Using immunity challenge techniques 17 flocks from 12 to 72 weeks of age showed significantly lower lesion scores for the first three species compared with susceptible control flocks similarly challenged. Only one flock was found to be susceptible to E. tenella. No mortality occurred in the field flocks after challenge while 20 to 60% mortality occurred in the susceptible controls. 3. Partial immunity occurred more frequently in field flocks aged 28 weeks of age or less (62%) than in older flocks (30%). Lesion scores ranged from 0-1 to 2-2 with the former and 0-1 to 0-6 with the latter group. 4. A modification of the immunity challenge method was developed using lesion scores as the major criterion determining immunity. The method permits testing of four species infecting different parts of the digestive tract in one group of birds.

Animals↗
PubMedDate not supplied

Interaction of infectious bursal disease and coccidiosis in layer replacement chickens.

During a floor-pen study on anticoccidial programs for layer-replacement pullets, there was a natural outbreak of infectious bursal disease (IBD). The interaction of coccidiosis and IBD was characterized by: excessive deaths from coccidiosis; and apparent failure of some anticoccidial drug treatments. Immunity to coccidiosis was not blocked by the IBD infection, although immunity was less in some treatments than would be expected with the degree of coccidiosis exposure.

Animals↗
PubMedDate not supplied

Development of immunity to coccidiosis in chickens administered anticoccidials in feed.

New combinations of techniques were employed for comparing the development of immunity of Eimeria tenella in chickens being medicated with 12 different anticoccidials. Broiler-type birds in batteries received a daily measured dose of E. tenella oocysts for 15 consecutive days while the drug was administered at the manufacturer's recommended level. Two or more tests of each drug gave the following ratings: strong suppression, monensin (121 ppm), salinomycin (80 ppm), lasalocid (75 ppm); moderate suppression, monensin (100 ppm), decoquinate (30 ppm), clopidol (125 ppm), and narasin (80 ppm); slight suppression, arprinocid (70 ppm), nicarbazin (125 ppm), and amprolium (125 ppm + ethopabate (4 ppm); no effect, robenidine (33 ppm), zoalene (125 ppm), and aklomide (250 ppm).

Amprolium↗