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Biomedical subjects

K Johansson

Publications and source records attributed to K Johansson.

At least 145 records · Page 8Linked to original sources
PubMed1991

Influence of fibre diameter and probe geometry on the measuring depth of laser Doppler flowmetry in the gastrointestinal application.

The measuring depth of laser Doppler flowmetry (LDF) was studied in isolated segments of feline small intestine, using five probes having different fibre geometry, fibre core diameter and fibre centre separation. Recordings were made on the mucosal side at constant systemic blood pressure and venous outflow from the bowel segment. The insertion of a layer of unperfused intestine (average thickness 2.4 mm), between the probe and the perfused bowel wall, reduced the output signal from the flowmeter to an average of 42% of the initial value when a probe with large diameter fibres (700 microns) was used. No LD-signal was obtained through the unperfused tissue layer using the probes with small core diameter fibres (120 microns). Application of a mirror at the serosal surface opposite to the probe, resulted in an average increase of the output signal by 50% using the large fibre diameter probe, whereas no increase was observed with the small fibre probe. Probes based on intermediate fibre diameter and fibre centre separations, gave intermediate results in both experiments. It is concluded that the measuring depth of laser Doppler flowmetry in the gastrointestinal application is highly dependent on the fibre diameter and geometry of the probe. It is possible that, by taking into account these factors, probes may be constructed that are suitable for superficial and transmural measurements.

Animals↗
PubMed1990

Phorbol ester treatment down-regulates immunoglobulin RNA steady-state levels in B type chronic lymphocytic leukemia and non-Hodgkin's lymphoma cells.

The human B-lymphoma cell lines BJAB and Daudi, as well as the human pre-B cell line KM3, were found to down-regulate steady-state immunoglobulin RNA levels 2- to 4-fold after stimulation with phorbol 12-myristate-13-acetate (PMA) for 24 hr. No down-regulation of the transcriptional rate of a kappa promoter could be observed in any of these cell lines upon transient expression transfection. The observed down-regulation of steady-state immunoglobulin RNA affected both the secretory and the membrane form of the mu transcript equally. When freshly isolated chronic lymphocytic leukemia (CLL) cells where tested for their response to PMA, three of four isolates responded by down-regulating their steady-state immunoglobulin RNA levels.

Animals↗
PubMed1989

Laser Doppler flowmetry in experimental mesenteric vascular occlusion.

The performance of the laser Doppler-signal (measuring blood flow) and the direct current-signal (measuring the amount of backscattered light) were studied in isolated segments of feline small intestine during arterial or venous occlusion. Following total arterial or venous occlusion, the LD-signal rapidly fell to 16% and 29% of control values, respectively. The DC-signal decreased significantly (to 78% of control, p less than 0.001) in response to venous occlusion but did not change significantly following arterial occlusion. After total venous occlusion, the amount of backscattered light was sometimes insufficient to allow flow measurement, probably due to high light absorption in the congested tissue. After ligation of the vascular stalk, the LD-signal soon decreased to 10-15% of control but did not reach the baseline until 4-6 hours. It is suggested that this residual LD-signal is caused by activity in the muscularis layer in the early phase of intestinal infarction.

Animals↗
PubMed1988

Changes in the central projection pattern of vibrissae innervating primary sensory neurons after peripheral nerve injury in the rat.

The central representation of a normal vibrissa nerve and the corresponding nerve after transection and regeneration of the infraorbital nerve has been studied by the use of transganglionic transport of horseradish peroxidase in the adult rat. The normal vibrissa nerve terminated in a well-defined area within nucleus caudalis and C1 dorsal horn. In contrast, the regenerated vibrissa nerve showed a widespread central termination pattern indicating a pronounced loss of somatotopic organization. These changes in somatotopic organization could contribute to an inability to correctly localize a sensory stimulus; this is a common clinical finding after peripheral nerve injury and regeneration.

Animals↗
PubMed1988

Effect of epidural anaesthesia on intestinal blood flow.

The effect of epidural bupivacaine (5 mg/ml) on intestinal blood flow was studied with laser Doppler flowmetry in 15 patients during operations including various types of large bowel resection. In the colon, blood flow increased in 13 out of 15 patients, which was significant at the 1 per cent level. The average increase was 41 per cent. In the ileum an increase was found in eight out of eleven patients who could be studied, which was significant at the 5 per cent level. Bowel function was restored satisfactorily in all patients. It is concluded that epidural bupivacaine has a favourable effect on intestinal blood flow during colorectal surgery.

Adult↗
PubMed1988

Effect of continuous postoperative epidural analgesia on intestinal motility.

The effect of postoperative epidural bupivacaine on intestinal motility was studied by measuring the transit time of barium contrast through the intestines in 16 patients after resection of the left colon and/or rectum. Fourteen patients served as controls and received postoperative injections of pentazocine. Mean transit time through the intestinal tract was 35 h in the epidural group and 150 h in the control group, a difference that is significant at the 0.1 per cent level. The average time before passage of flatus and faeces was different between the two groups at the 0.1 per cent level. We conclude that postoperative epidural bupivacaine constitutes an effective means of analgesia after colorectal surgery and is associated with a short duration of intestinal paralysis.

Aged↗
PubMed1988

Sympathetic nerve fibers in peripheral sensory and motor nerves in the face of the rat.

Retrograde transport of horseradish peroxidase (HRP) has been used to investigate whether postganglionic neurons in the superior cervical ganglion send branches into various peripheral nerves in the rat. HRP was applied to the zygomatic branch of the facial nerve, the mental nerve, deep vibrissae nerves and to nerves in the tooth pulp. HRP-labeled neurons were consistently seen in the SCG in all types of experiments, except for the cases where HRP was applied to the tooth pulp.

Animals↗
PubMed1988

Assessment of gastric blood flow with laser Doppler flowmetry.

The use of laser Doppler flowmetry (LDF) to measure gastric blood flow was evaluated in the cat and man. The reproducibility of laser Doppler flowmetry recordings was studied in the feline stomach. In five cats flowmeter signals and venous outflow of the stomach were simultaneously recorded. The flowmeter recordings were made during operation and gastroscopy in 140 patients by means of two different (PF1-4-kHz and PF2-12-kHz) laser Doppler systems. The flowmeter recordings were highly reproducible during the cat experiments, with a coefficient of variation varying between 4% and 13%. Angulation of the probe within 60-120 degrees against the tissue under study did not affect the flowmeter signal. Pressure of the probe against the studied tissue attenuated the flowmeter signal 42 +/- 13% (n = 10). A significant correlation coefficient (r = 0.76; p = 0.01; n = 30) was obtained between flowmeter signal and venous outflow of the stomach. In man the PF2-12-kHz system yielded a higher flowmeter signal (14.5 +/- 6.9 V; 32 patients) than the PF1-4-kHz system (7.9 +/- 2.5 V; 108 patients). Flow dimensions were calculated by using results previously obtained in the intestines. The estimated blood flow values amounted to 31 +/- 10 and 57 +/- 27 ml min-1 100 g-1 for the PF1-4-kHz and PF2-12-kHz systems, respectively. In conclusion, laser Doppler flowmeter is a promising technique for studying gastric perfusion during operation and endoscopy. Motion artifacts are the major drawback of the present laser Doppler systems.

Adult↗
PubMed1988

Assessment of gastrointestinal blood flow with laser Doppler flowmetry in patients with chronic radiation injury.

Laser Doppler flowmetry was used for pre- and intraoperative assessment of gastrointestinal blood flow and vascular damage in eight patients with late radiation injury of the gastrointestinal tract. The flowmeter recordings were compared with reference values previously obtained in unaffected tissue from corresponding gastrointestinal sites. Marked reduction of blood flow was demonstrated in macroscopic areas of radiation injury in all eight patients. Five also showed varying degrees of disturbed blood flow in adjacent macroscopically normal bowel segments with histologically varying severity of radiation injury. In a ninth patient radiation injury was clinically suspected but could not be demonstrated with laser Doppler flowmetry or histologically. The extent of radiation injury often is underestimated from clinical signs, and laser Doppler flowmetry during surgical treatment of late radiation injury to the gastrointestinal tract provides substantial information concerning the extent of vascular damage.

Adult↗
PubMed1988

Gastrointestinal application of laser Doppler flowmetry. An experimental and clinical study in cat and man.

Laser Doppler flowmetry (LDF) was evaluated as a method for study of gastrointestinal blood flow with emphasis on clinical applicability in man. Measuring depth of LDF in the gastrointestinal tract was studied in cat and man. The LD-signal was attenuated in an exponential manner by unperfused intestinal tissue between the probe and the perfused organ. With a probe with optical fibre diameter of 0.7 mm, the measuring depth was approximately 6 mm i.e. transmural in most parts of the gastrointestinal tract. In experimental mesenteric vascular occlusion on feline small intestine, it was possible to discriminate arterial and venous occlusion by simultaneous recording of the total amount of backscattered light. The effect of epidural anaesthesia on intestinal blood flow was studied in 15 patients during large bowel resections. A significant increase of total blood flow was found in the colon (p less than 0.01) and the small intestine (p less than 0.05), with an average increase of 41% and 15% respectively. LDF was used intraoperatively for assessment of the extent and degree of disturbed microcirculation in 8 patients with late radiation injury of the gastrointestinal tract. The flow values obtained were compared with reference values earlier obtained in unaffected tissue from corresponding gastrointestinal sites. Severe reduction of blood flow was demonstrated in segments with visible fibrosis. Five segments also showed varying degrees of disturbed blood flow in adjacent macroscopically normal bowel with histological radiation injury. In patients with radiation injury of the rectum, it was possible to assess the extent of vascular damage in the rectum prior to surgery by endoscopic flowmeter recording. The post-operative course was uneventful in all patients. In 23 patients with small bowel ischemia of different origins, LDF proved valuable for assessment of blood flow and tissue viability. In patients with mechanical strangulation, bowel resection was avoided in 9 out of 10 segments of clinically uncertain viability following flowmeter recording. In 6 patients with mesenteric vascular occlusion, the extent of severe ischemia seemed underestimated by clinical judgement compared to the results obtained with LDF. The ability of LDF to detect small ischemic areas and to select the proper level of resection was demonstrated. It is concluded that LDF is a suitable method for study of gastrointestinal blood flow in experimental and clinical work. LDF provides substantial information in the intraoperative management of small bowel ischemia and late radiation injury of the gastrointestinal tract.

Anesthesia, Epidural↗
PubMed1987

Simultaneous liquid chromatographic determination of seventeen of the major monoamine neurotransmitters, precursors and metabolites. I. Optimization of the mobile phase using factorial designs and a computer program to predict chromatograms.

Utilizing reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection and optimization of the mobile phase using factorial designs and a constructed computer program to predict chromatograms, it has been possible to obtain a satisfactory resolution of seventeen of the major monoamine neurotransmitters, precursors and metabolites. A rapid (less than 25 min) isocratic system for the simultaneous determination of 3,4-dihydroxyphenylalanine, dopamine, dihydroxyphenylacetic acid, 3-methoxytyramine, homovanillic acid, norepinephrine, normetanephrine, 3,4-dihydroxyphenylethylene glycol, 3-methoxy-4-hydroxyphenylethylene glycol, epinephrine, metanephrine, vanillylmandelic acid, 5-hydroxytryptophan, serotonin, 5-hydroxytryptophol and 5-hydroxyindoleacetic acid in addition to the internal standard isoproterenol is presented. The optimization strategy included selection of variables to optimize by a reduced factorial design a detailed study of these variables by a complete factorial design, theoretical predictions of chromatograms by a constructed computer program and test on the HPLC system. This optimization strategy can easily be applied to any problem of solute separation by liquid chromatography.

Chromatography, High Pressure Liquid↗
PubMed1987

Effects of acute haemorrhagic hypotension during pregnancy and lactation in conscious goats.

Effects of acute, short-lasting haemorrhage have been studied in six goats. The experiments were made 55 +/- 3 days (mid-pregnancy = MP), and 24 +/- 2 days (late pregnancy = LP) before parturition, in lactation weeks 3-8, and in the non-pregnant, non-lactating (= control) period. The room temperature was kept at 20 +/- 1 degrees C, except during one experimental series in lactating goats, which was performed at +30 degrees C. Approximately the same volume of blood had been removed in all periods, when the mean arterial blood pressure (MAP) fell. At this moment bleeding was stopped. The volume loss, calculated as per cent of total blood volume, was significantly smaller during pregnancy and lactation than in the control period. The fastest heart rate, both at rest and during haemorrhage, was observed in LP goats. The respiratory frequency of the LP goats increased markedly in response to haemorrhage, but the most rapid respiratory rate was observed in lactating goats bled at the room temperature +30 degrees C. The increase in plasma vasopressin (AVP) concentration coincided with the fall in MAP. The AVP rise seen during late pregnancy was significantly higher than in all the other periods. The plasma noradrenaline (NA) concentration increased by about five times in LP goats, but did not change significantly in the other periods. Plasma renin activity did not rise, with the exception of a small increase in lactating goats bled at +30 degrees C. The plasma aldosterone concentration rose, but there was no difference between periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1987

Intravenous indomethacin and oxycone-papaverine in the treatment of acute renal colic. A double-blind study.

In a prospective double-blind, cross-over study, 61 patients with acute renal colic were treated with either indomethacin (50 mg) or oxycone-papaverine (5 mg + 50 mg) administered intravenously. For those patients requiring a second injection the drugs were reversed. The intensity of pain was evaluated before and 20 min after each injection according to an analogue visual scale 0 to 100. Both drug regimens provided comparable and significant pain relief; a pain score of less than 20 appeared to be satisfactory and was achieved in almost all cases.

Acute Disease↗
PubMed1987

Tissue penetration and measuring depth of laser Doppler flowmetry in the gastrointestinal application.

Tissue penetration of laser light and measuring depth (depth sensitivity) for laser Doppler flowmetry in the gastrointestinal application were studied in the feline and human bowel and stomach with a wall thickness of from 2.1 to 7.0 mm. Mucosal and serosal recordings from corresponding sites in the gastrointestinal tract were comparable and in the intestine correlated to total blood flow. Laser light was reflected by a mirror placed on the opposite side of the bowel wall, and hyperemic reactions were similarly recorded from both sides of the bowel with wall thickness up to 6 mm. Placing layers of unperfused feline small intestine (average thickness, 2.1 mm) between the probe and the perfused feline gastric wall attenuated the laser Doppler signal in an exponential manner. We conclude that with this instrument, the tissue penetration and measuring depth of laser Doppler flowmetry are at least 6 mm in the gastrointestinal application.

Animals↗
PubMed1986

Ammonium chloride induced acidosis and aldosterone secretion in the goat.

Responses to 30-min intraduodenal infusion of NH4Cl (total amount 75 mmol) were studied in conscious goats. The infusion caused an immediate, transient rise in plasma aldosterone concentration (PA) from a mean of 78 to 221 pmo l-1. As expected, the NH4Cl administration also induced metabolic acidosis, initially subjected to partial respiratory compensation. The acidosis did not become fully developed until 1 h after cessation of the infusion, when PA had almost returned to its initial level. Renal compensation of the acidosis was shown by acidification of the urine and reduced Na excretion being most pronounced 1-2 h post-infusion. During the infusion blood haemoglobin concentration and the haematocrit increased by 25 and 13%, respectively, without simultaneous increase in plasma protein concentration and with persisting ear vasodilatation, indicating a mobilization of stored erythrocytes in the absence of a general increase in sympathetic tone. The results suggest that the reduction of blood pH is not the cause of the increase in PA occurring in association with NH4Cl-induced metabolic acidosis, but leave open the possibility that this increase may be due to some centrally mediated or direct adrenal influence of NH+4. As regards the apparent NH4Cl-induced mobilization of stored erythrocytes, it is suggested that such a response may play a role in the defence against acidosis by increasing the buffering capacity of the circulating blood.

Acid-Base Equilibrium↗
PubMed1986

Local blood flow changes in association with proximal gastric vagotomy.

Local blood flow changes in association with proximal gastric vagotomy were studied with laser Doppler flowmetry in 10 patients. After the vagotomy a significant decrease in blood flow amounting to 57 +/- 21% (range, 18-87%; p less than 0.001) was observed within the dissected area along the lesser curvature. In three patients, the flowmeter recordings suggested localized areas with very poor perfusion. The blood flow was restored to preoperative control values within 3-4 weeks after the operation. It is suggested that the temporary poor blood perfusion along the lesser curvature may be an important factor in the genesis of postoperative ulcerations in the dissected area. We conclude that laser Doppler flowmetry seems to have great potential as a method to study localized blood flow changes in the stomach. Flowmeter recordings can be made both during operation and endoscopy.

Humans↗