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Biomedical subjects

K Johansen

Publications and source records attributed to K Johansen.

At least 55 records · Page 3Linked to original sources
PubMed1996

Pelvic revascularization by direct hypogastric artery reconstruction.

BACKGROUND: While pelvic arterial insufficiency, either acute or chronic, results in stereotypic clinical findings which may readily be reversed by indirect techniques of revascularization, few reports document the indications for, techniques of, and results following direct pelvic revascularization by reconstruction of the hypogastric artery. METHODS: Retrospective review of 8 patients with symptomatic pelvic arterial insufficiency undergoing direct hypogastric artery reconstruction during the period from 1984 to 1995. RESULTS: Eight patients underwent unilateral hypogastric artery reconstruction by bypass graft (3 patients) or endarterectomy and patch angioplasty (5 patients). One patient had immediate symptomatic relief of his symptoms, but was lost to follow-up after 1 month. One patient manifested no symptomatic improvement despite a technically successful operation. The remaining 6 patients experienced significant symptomatic relief that has persisted during follow-up from 3 months to 11 years postoperatively. Among 4 men in whom erectile impotence comprised one of the indications for intervention, 3 reported sustained restoration of sexual function. CONCLUSION: In properly selected patients, direct pelvic revascularization by hypogastric artery reconstruction may predictably and durably relieve symptoms of pelvic arterial insufficiency.

Adult↗
PubMed1996

Passive immunity against diarrhoea.

Passive immunity against a variety of respiratory and gastrointestinal pathogens has recently been increasingly used clinically, and oral administration of antibodies of both human and non-human origin has been tried both for prophylaxis and treatment of infections. Although the former type of therapy has been shown to be effective, data on the latter are still scarce. This commentary focuses on recent studies on successful oral therapeutic administration of bovine immunoglobulins.

Animals↗
PubMed1995

Solid-phase microextraction for the determination of the free concentration of valproic acid in human plasma by capillary gas chromatography.

The potential of solid-phase microextraction in the bioanalysis of drugs is demonstrated. The free concentration of valproic acid in human plasma was determined by equilibrium dialysis at room temperature. To the dialysate was added an internal standard and the pH was adjusted to 2.5. The polymethylsiloxane-coated fused-silica fibre of the solid-phase microextraction device was inserted into the dialysate for 3 min. The sorbed analytes were then thermally desorbed at 210 degrees C in the split-splitless injection port of the gas chromatograph, separated on a Nukol capillary column and detected with a flame ionization detector. The method was shown to be highly reproducible with a detection limit of 1 microgram/ml of free valproic acid in human plasma.

Chromatography↗
PubMed1995

Automated analysis of free and total concentrations of three antiepileptic drugs in plasma with on-line dialysis and high-performance liquid chromatography.

A fully automated method for determination of the free and total concentration of drugs with a varying degree of protein binding is described. The antiepileptic drugs phenytoin, carbamazepine and phenobarbitone were chosen to demonstrate the utility of this technique. The method was based on the ASTED system and combined on-line equilibrium dialysis at 37 degrees C with concentration of the dialysate on a trace enrichment column and HPLC determination with UV detection. The dialysis cell was a modification of the ASTED dialysis cell and 22% of the free concentration of the drugs were recovered in the recipient channel of the dialyser after 10 min of dialysis at 37 degrees C. The free concentration, the total concentration as well as the drugs protein binding could be determined. The method was shown to be well suited for routine monitoring of the free and the total concentrations of the drugs in plasma from epileptic patients.

Anticonvulsants↗
PubMed1995

Pharmacologic intervention to prevent graft failure.

Lower extremity vascular grafts, either vein or synthetic, fail for diverse reasons. Technical defects or poor surgical judgment doom a graft beyond any benefit pharmacotherapy can offer. Graft failure due to spontaneous thrombosis particularly affects prosthetic conduits, and use of antiplatelet agents (dextran, ASA) or anticoagulants (heparin, warfarin) is probably useful in this setting. An effective way to inhibit vein graft or anastomotic intimal hyperplasia remains elusive. Perhaps the most permanent and longstanding influence on lower extremity graft survival can be made through risk factor intervention aimed at arresting the progression of atherosclerosis. Aggressive treatment of hyperlipidemia, hypertension, smoking, and other known risk factors should be routinely and aggressively pursued in patients with lower extremity grafts, either autogenous or prosthetic. Lower extremity graft patency is optimally ensured by technically adept insertion of a proper autologous conduit in a well-selected patient. Pharmacotherapy may have a significant adjunctive role in the maintenance of graft patency, especially in high-risk settings such as limb salvage with associated poor outflow, a marginal vein graft, or the obligatory use of prosthetic material.

Anticoagulants↗
PubMed1995

Essential thrombocytosis: underemphasized cause of large-vessel thrombosis.

PURPOSE: The purpose of this study was to describe the clinical course of patients seen with large-vessel thrombosis in association with essential thrombocytosis (ET). METHODS: This study was a retrospective review of all patients treated for large-vessel thrombosis caused by ET during a 2-year period at University of Washington teaching hospitals. RESULTS: Five patients presented with arterial (femoral-popliteal-tibial: aortic), portal (two cases), or systemic venous (inferior vena cava) thrombosis and required operation. Two were known to have ET; in three others ET was diagnosed after operation when platelet counts persistently in excess of 500,000/mm3 were noted. The diagnosis of ET was established in each case by ruling out causes of reactive thrombocytosis and (in the three new cases) by evidence for megakaryocyte hyperplasia on bone marrow biopsy. Platelet counts in all five patients were reduced to normal levels by cytoreductive therapy, and no further thrombotic episodes have occurred during 18 months (mean) of follow-up. During this 2-year period ET accounted for more large-vessel thrombotic complications in our institutions than all other more frequently described hypercoagulable states combined. CONCLUSIONS: ET is an underemphasized cause of large-vessel thrombosis.

Adult↗
PubMed1995

An unusual type of familial lipodystrophy.

A mother and her daughter with a novel type of familial partial lipodystrophy were studied. Both had atrophy of fat in the face, chest, and upper and lower limbs and abdominal obesity caused by intraabdominal fat accumulation. The mother had severe insulin resistance and impaired glucose tolerance, whereas the daughter had normal glucose tolerance and normal insulin sensitivity. Both had metabolic rates about 30% above normal levels, but normal thyroid function and plasma lipids.

Abdomen↗
PubMed1994

Specific pathway selection by the early projections of individual peripheral sensory neurons in the embryonic medicinal leech.

In leech, the central annulus of each midbody segment possesses seven pairs of sensilla, which are mixed clusters of primary peripheral sensory neurons that extend their axons into the CNS where they segregate into distinct fascicles. Pathway selection by individual afferent growth cones of sensillar neurons was examined by double labeling using intracellular dye-filling with antibody labeling in early Hirudo medicinalis embryos. The monoclonal antibody Lan3-2 was used because sensillar neuronal tracts are specifically labeled by this antibody. Examining 68 individually filled neurons we found that sensillar neuron growth cones bifurcate within the CNS, that they project long filopodia capable of sampling the local environment, and that all of them appeared to choose a single particular CNS fascicle without apparent retraction or realignment of growth cones. Furthermore, each side of the bifurcating afferent growth cones always chose the same fascicle, implying a specific choice of a distinct labeled pathway. By dye-filling individual central neurons (P-cells), we show that there are centrally projecting axons present at the time sensillar afferents enter the ganglionic primordia and select a particular fascicle, and we confirm that at least the dorsal peripheral nerve is likely to be pioneered by central neurons, not by the peripheral afferents. In the sensillum studied here, we found examples of sensory neurons extending axons into one of all the available fascicles. Thus, an individual embryonic sensillum possesses a heterogeneous population of afferents with respect to the central fascicle chosen. This is consistent with the idea that segregation into distinct axon fascicles may be based upon functional differences between individual afferent neurons. Our findings argue strongly in favor of specific pathway selection by afferents in this system and are consistent with previous suggestions that there exists a hierarchy of cues, including surface glycoconjugates that mediate navigation of the sensillar growth cones and the fasciculation of their axons.

Animals↗
PubMed1994

Serum IgA immune response to individual rotavirus polypeptides in young children with rotavirus infection.

A human IgA-radioimmunoprecipitation assay (IgA-RIPA) utilizing the galactose-binding lectin jacalin from the jack-fruit Artrocarpus integrifolia was developed. Among the human immunoglobulins, jacalin binds specifically to immunoglobulin A. The IgA-RIPA was used to characterize the serum IgA response to individual rotavirus polypeptides in nine paired sera from children (8-34 months of age) with an acute rotavirus infection. In acute sera the IgA response was mainly directed against the inner capsid proteins VP2 and VP6, with VP2 surprisingly being the most immunogenic protein while in the convalescent sera, the IgA response was directed not only against structural but also against non-structural proteins.

Antibodies, Viral↗
PubMed1994

Optimal outcome for "high-risk" carotid endarterectomy.

While carotid endarterectomy (CEA) can often be accomplished with a very low stroke risk, certain scenarios--prior ipsilateral stroke, contralateral carotid occlusion, or acute cerebral ischemia--have been associated with neurologic morbidity and mortality rates exceeding 10%. The routine use of temporary intraluminal carotid shunts has been thought to be obligatory in such patients, notwithstanding the fact that these devices are obtrusive and may be associated with an increased risk of perioperative stroke. Among 175 patients undergoing CEA, 68 could be classified as "high-risk" (contralateral carotid occlusion, n = 24; prior ipsilateral stroke, n = 28; acute cerebral ischemia, n = 16). CEA was performed under regional or local anesthetic block in all 68 patients. Sixty-six patients (97%), including 22 of 24 (92%) with contralateral carotid occlusion, underwent CEA (carotid occlusion times averaging 22 minutes [range: 12 to 42 minutes]) without insertion of a carotid shunt. Two patients (2.9%) with contralateral carotid occlusion lost consciousness 7 and 10 minutes after carotid clamping, but regained neurologic normalcy after shunt insertion. A single patient (1.5%) experienced a fatal stroke due to heparin-induced "white clot" syndrome. Rates of shunt insertion and of perioperative stroke did not differ from those in 107 "low-risk" CEA patients. Cerebral collateral circulation is well developed even in compromised CEA patients. The necessity for temporary carotid shunts may be reduced by the use of "awake" anesthesia in such cases. Carotid shunting may be no more necessary, and operative outcome no less favorable, in "high-risk" than in uncomplicated CEA patients.

Carotid Arteries↗
PubMed1994

Biomaterials for hemodialysis access.

While the optimal vascular conduit for hemodialysis is undeniably an arterialized autogenous subcutaneous vein, only a minority of end-stage renal disease patients can count on such access: the remainder require implantation of a biomaterial conduit. This paper will briefly survey current biografts used for hemodialysis access, with an emphasis on their known limitations, and will delineate the questions to be asked--and answered--in the development of optimal dialysis access grafts.

Arteriovenous Shunt, Surgical↗
PubMed1993

Radial or ulnar artery laceration. Repair or ligate?

OBJECTIVE: To determine the relationship between patency of radial or ulnar artery repair and later hand symptoms. DESIGN: Call-back survey. SETTING: Urban trauma center. PATIENTS: Thirty-two subjects with wrist artery lacerations undergoing 26 arterial repairs and six artery ligations during an 8-year period. INTERVENTIONS: Directed history and hand examination (palpation of wrist pulses, Doppler Allen test, and Doppler interrogation of palmar arch and digital vessels). MAIN OUTCOME MEASURES: History of hand claudication, weakness, or cold sensitivity or paresthesias and patency of wrist arteries. RESULTS: Twelve (46%) of 26 wrist artery repairs were patent. There was no evident benefit of optical magnification or specialization in hand or vascular surgery. No subjects had hand claudication; there was a 50% incidence of hand weakness and a 12% incidence of cold sensitivity independent of patency of the damaged wrist artery and present only in subjects with associated nerve injury. Professional charges for wrist artery repair were threefold to fourfold higher than those for wrist artery ligation. CONCLUSION: Consonant with prior reports, patency following repair of radial or ulnar artery laceration does not exceed 50%. Later hand symptoms relate to nerve or tendon damage, not to arterial patency. In the absence of acute hand ischemia, simple ligation of a lacerated radial or ulnar artery is safe and cost-effective.

Adolescent↗