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Biomedical subjects

G Karlström

Publications and source records attributed to G Karlström.

At least 73 records · Page 4Linked to original sources
PubMed1985

Effects of high and low sodium diets on the resistance vessels and their adrenergic vasoconstrictor fibre control in normotensive (WKY) and hypertensive (SHR) rats.

As part of our studies in normotensive (WKY) and hypertensive (SHR) rats concerning the cardiovascular effects of 240-fold variations in sodium (Na) intake, the present experiments explore how vascular design, smooth-muscle sensitivity to noradrenaline and adrenergic vasoconstrictor fibre function are affected. In vitro comparisons were performed on pair-perfused hindquarter vascular beds and on paired small mesenteric arteries (diameter 150-200 micron), using a two-vessel Mulvany-Halpern myograph. Preparations were taken from WKY and SHR which between 5 and 12-13 weeks of age were on 'low' (LNa, 0.5), 'control' (CNa, 5), 'high' (HNa, 50) or 'very high' (vHNa, 120 mmol Na 100 g-1 food) sodium diets. Structural vascular adaptation occurred only when arterial pressure was altered (only in LNa SHR). In both preparations smooth-muscle sensitivity and dose-response curves to noradrenaline remained unaffected by the Na diets. However, in both LNa groups the frequency-response curves to vasoconstrictor fibre stimulation in the small arteries were displaced to the right of the CNa one, with generally attenuated responses, while the curves of particularly the vHNa arteries were displaced to the left, with enhanced responses. Inhibition of NaKATPase by ouabain particularly enhanced the neurogenic responses, but to similar extents in all Na groups. Thus, low sodium intake apparently reduces the transmitter release/impulse in adrenergic neurons, while it increases the transmitter stores. High sodium intake has the opposite effects. These adaptations of adrenergic neuronal function may be one of the most important long-term consequences of altered sodium intake.

Adrenergic Fibers↗
PubMed1985

Recurrent dislocation after total hip replacement. Treatment by fixing an additional sector to the acetabular component.

Six patients with recurrent dislocation after total hip replacement have been treated by fixing an additional sector to the acetabular component. Muscle imbalance or unsatisfactory positioning of the prosthetic components (or both) had caused the dislocations in five patients. In the sixth, a schizophrenic, the dislocations were due to the positions in which the patient placed his limb. At operation a sector was cut from another acetabular prosthesis and screwed on to the previously inserted acetabular component in such a position as to prevent further dislocation. This method has been successful and seems a simple alternative to exchange arthroplasty.

Aged↗
PubMed1985

Ender nailing of pertrochanteric fractures. Complications related to technical failures and bone quality.

In a series of 127 consecutive patients with trochanteric femoral fractures treated with Ender nailing, bone quality and technical failures were analysed. Of the fractures, 35 per cent were stable and 65 per cent unstable according to the definitions of Evans. There were no implant failures. Technical failures occurred in 16 cases. These could be referred to unsuitable location of the nails in the femoral head and/or to an insufficient fixation of the nails in the medullary cavity, especially in patients with poor bone quality and unstable fractures. Technical failures should therefore be preventable. When a correct surgical technique is used with a sufficient number of nails in femurs with low bone quality and a wide medullary canal, the method seems to be a simple and safe treatment for most pertrochanteric fractures, with elimination of many of the problems often associated with this injury.

Aged↗
PubMed1984

Subtrochanteric fractures. Classification and results of Ender nailing.

With use of a simple classification based on anatomical criteria and anatomical function, 27 subtrochanteric fractures of the femur were studied. The series was derived from 156 elderly patients with extracapsular hip fractures, all of whom were operated on by the Ender method. There were no infections. Regarding intra- and postoperative bleeding, early mobilization, length of hospital stay, and final clinical outcome, the results were superior to those obtained with other methods so far presented. Three patients died within 3 months postoperatively. Technical failure occurred at an early stage in 4% and at a later stage in 12.5%. Short oblique fractures did not require any supplementary fixation. Neither comminution nor obliquity prevented early mobilization with full weight-bearing. Tibial traction for a short period in one patient did not prevent expected mechanical failure. The mean time in hospital was 19 days. The functional result was excellent or good in 79% of the patients.

Aged↗
PubMed1984

The influence of age on the morphology of trochanteric fracture.

A series of 127 trochanteric femoral fractures was analyzed with respect to fracture type, age, and bone quality (osteoporosis). There was a continuous decrease in bone quantity (measured as femoral score) with age and a direct relation between bone quality and the severity of the pattern of the trochanteric fracture. The skeletal ageing process starts earlier in women. However, after the age of 85 years the process is more rapid in men. Consequently, the risk of sustaining a trochanteric fracture is greater in men than in women above this age. The increasing age of the population and the longer survival of the oldest people results in more unstable and more comminuted fractures, which have increased by a factor of nearly 3 during the past three decades.

Age Factors↗
PubMed1984

How do changes in diameter at the precapillary level affect cardiovascular function?

A survey is given of the various high-pressure precapillary vascular sections and of how they affect local and overall cardiovascular functions, with special emphasis put on the important "precapillary resistance vessels." The complex interactions between hemodynamic effects dependent on (a) vessel design, (b) transmural pressure, (c) "passive" wall distensibility, and (d) "active" smooth muscle responses are outlined in principle and experimentally illustrated with respect to systemic resistance control. Particular attention is devoted to the influence of the sympathetic vasoconstrictor fibers on precapillary vascular functions, concerning aspects such as speed, precision, range, and differentiation of the neurogenic effects, because these fibers represent the most powerful and widespread of the vascular control mechanisms involved in cardiovascular homeostasis. How these fibers in well-innervated vascular circuits can command up to the maximum contractile capacity of both the precapillary resistance and postcapillary capacitance vessels is illustrated, as well as the way in which these sets of vessels respond to even single nerve impulses with twitchlike, rapid contractions.

Animals↗
PubMed1984

Age- and pressure-dependent changes of systemic resistance vessels concerning the relationships between geometric design, wall distensibility, vascular reactivity and smooth muscle sensitivity.

The resistance vascular function in normotension, and its alterations in primary hypertension and ordinary aging, was analysed concerning the interactions between geometric vascular design, wall distensibility, transmural pressure and smooth muscle activity. Paired hindquarter perfusions were used, comparing hemodynamic resistance characteristics in young, adult and old normotensive (WKY) and spontaneously hypertensive rats (SHR). From the experimental data pressure-resistance diagrams were constructed, which quantitatively interrelate the four factors in all SHR-WKY groups. The diagrams show, over a wide pressure range, how altered smooth muscle activity as well as structural adaptation affect resistance vessel distensibility; likewise how distensibility considerably interferes with "active" resistance adjustments. They also show how markedly the range of active resistance responses during ordinary constant-pressure perfusion is affected whenever pressure is reset to new levels. Finally, the diagrams illustrate the fundamental hemodynamic difference between hypertensive and normotensive resistance vessels, mainly because of factors 1 and 2, which render the hypertensive vessels stronger, stiffer and hyperreactive. Thereby they are capable of a widened response range despite the higher pressure level, which is further accentuated on acute pressure normalization. In contrast, ordinary aging alters resistance vascular behaviour only little, smooth muscle contractility and sensitivity remaining almost unchanged. However, vascular reactivity is moderately enhanced at lower pressures, presumably a geometric consequence of age-dependent, intimal-interstitial endowment.

Aging↗
PubMed1984

Cardiovascular studies in rats with respect to some functional and structural relationships of relevance in hypertension and ordinary aging.

Five current lines of cardiovascular studies in rats are outlined, mainly dealing with some functional and structural relationships of particular relevance for hypertension and ordinary aging: 1. Characteristics of the smooth muscles and their neurogenic control in 'Windkessel' arteries, conduit arteries, precapillary resistance vessels and venous capacitance vessels from normotensive rats (WKY) with comparisons to rats with primary hypertension (SHR). 2. Different types of structural renovascular adaptation, comparing aging with advancing SHR hypertension, with 'high-pressure' and 'low-pressure' kidneys in one-clip, two-kidney renal hypertension, and with hypertrophied kidneys in uni-nephrectomized normotensive rats. 3. Relationships between 'structural autoregulation', wall distensibility, vascular reactivity and smooth muscle sensitivity in SHR and WKY hindquarter resistance vessels along with aging. 4. Relationships between wall thickness, luminal dimension and contractility in left ventricles from SHR and WKY during aging, and when one-clip, two-kidney hypertension is superimposed. 5. Interference with the capacity of the neurohormonal mechanisms counteracting blood loss in rats when on chronic low-salt diet.

Aging↗
PubMed1984

Rising incidence of hip fracture in Uppsala, 1965-1980.

The frequency and incidence of hip fracture in persons aged 55 years and older in the county of Uppsala during the years 1965, 1970, 1975 and 1980 are reported. For every 5-year interval, the number of hip fractures increased by 21-25 per cent. The ratio of women to men changed from 3.8 in 1965 to 3.1 in 1980. Trochanteric fractures were more common during the later years. The ratio of femoral neck fractures to trochanteric fractures decreased from 1.8 to 1.1 between 1965 and 1980. The incidence of hip fracture in the investigated part of the population increased from 43 per 10 000 in 1965 to 65 in 1980. The age-specific incidence increased especially in the group aged 85 years and older, in which fractures of the femoral neck were three times and trochanteric fractures four times more common in 1980 than in 1965. This investigation shows that the incidence of hip fracture has increased, particularly in the higher age groups. If the age-specific incidences continue to rise in the higher age groups, the frequency of hip fractures will be doubled within a 20-year period.

Age Factors↗
PubMed1984

Ender nailing of pertrochanteric fractures. Results at follow-up evaluation after one year.

One hundred twenty-seven patients with pertrochanteric femoral fractures were transfixed with the Ender nail. The mean age of the patients was 78.9 years. Thirty-five percent of the fractures were of the stable type, and 65% were of the unstable type. All patients had clinical and radiologic follow-up examinations every three months for one year. Successful closed reduction was achieved in 97.6% of the patients. Perioperative supracondylar femoral fractures occurred in two patients. The overall stay in hospital was 19 days. Technical failures occurred early in five patients, and late manifestations of major technical failures occurred in four patients. The average time to fracture union was 18 weeks. The primary mortality rate was 7%. From one to 12 months, the mortality rate increased to 15%. Of the 108 patients surviving the first year, 86% regained their prefracture activity-of-daily-living status. Ninety-six percent of the surviving patients returned to their prefracture residence, a very satisfactory outcome of a condition often observed as a terminal illness.

Activities of Daily Living↗
PubMed1984

Hip arthroplasty with an extended femoral stem for salvage procedures.

The problem of treatment of a combination of failed hip arthroplasty secondary to resorption, osteoporosis, osteolysis, or fracture is unsolved. Twenty-seven such complicated hips, including four with previous infection, were treated by a femoral prosthesis driven into an intramedullary nail. The goal of stability, allowing immediate mobilization, was attained in virtually all patients. The oldest was 84 years of age and the mean age was 69.3 years. In the early postoperative period, one patient died of pulmonary embolism and one of myocardial infarction. Two infections were treated 25 and 11 months after implantation; these patients were free from pain and showed no signs of loosening of the implant. The mean time in the hospital for the infected patients was 60 days and for the noninfected patients was 23 days. Among 14 patients who were observed for at least ten months after surgery, freedom from pain was achieved in eight, significant alleviation of pain in five, and slight improvement in one. Five patients also became completely free from dependence on walking aids; seven used one or two canes. Two patients were dependent on crutches. Discrepancy in the length of the lower limbs was noted in seven patients. Six patients showed 1 cm shortening and one patient 2 cm. In six patients the Trendelenburg sign was negative, and in only three patients was it clearly positive. The mean Harris Hip Score in 14 patients observed for more than ten months after surgery was 82. Intramedullary nailing combined with a femoral component in total hip arthroplasties, where defects or fractures of the femur have occurred, give good fixation of the implant components and a satisfactory functional result.

Adult↗
PubMed1983

Structurally based changes of renal vascular reactivity in spontaneously hypertensive and two-kidney, one-clip renal hypertensive rats, as compared with kidneys from uninephrectomized and intact normotensive rats.

Renal vascular beds from spontaneously hypertensive rats (SHR) at different stages of hypertension, from two-kidney, one-clip renal hypertensive rats (RHR) and from uninephrectomized rats (UNR) were in constant-flow, paired perfusions compared with kidneys from normotensive control rats (NCR) concerning vascular smooth muscle sensitivity to noradrenaline (NA) and resistance vessel reactivity, as reflected by the position, respectively the shape, of the dose-resistance response curves. None of these kidney variants differed significantly from controls concerning smooth muscle sensitivity to NA during in vitro perfusion. However, both the steepness and maximal pressor responses of the renal resistance curves increased progressively with age in SHR, to become ultimately much enhanced when related to age-matched controls. It suggests a well preserved smooth muscle contractility and a progressive elevation of the average wall/lumen ratio in the SHR renal resistance vessels. Also the untouched, "high-pressure" RHR kidneys showed increased vascular reactivity, while it was somewhat reduced in the clipped, "low-pressure" RHR kidneys and unchanged in the hypertrophied but normotensive UNR kidneys. These results, when combined with other findings concerning renal vascular design (Göthberg & Folkow 1982a), illustrate how the renal resistance vessels readily adapt structurally to hypertension, hypotension, kidney hypertrophy and also with age, and in directions which tend to chronically "autoregulate" glomerular blood supply and filtration.

Age Factors↗
PubMed1983

External fixation of severe open tibial fractures with the Hoffmann frame.

Extensive experience with stable external fixation of open tibial fractures has confirmed the observation that this method promotes healing of skin and soft tissue damage, reduces the risk of infection, and facilitates the treatment of patients with multiple injuries. In cases of very severe open fractures the method seems to be the treatment of choice and can reduce the frequency of amputation. Recently, complete long-term follow-up results showed that healing times can be reduced if the period of rigid external fixation is reduced. Functional end results after stable external fixation compare favorably with results of internal fixation with AO plates.

Accidents, Traffic↗
PubMed1983

Thromboembolism after total hip replacement: role of epidural and general anesthesia.

The effects of continuous epidural anesthesia and of general anesthesia on the incidence of thromboembolism following total hip replacement were studied. Sixty patients were randomly allotted to one of two groups receiving either epidural or general anesthesia. Epidural anesthesia (N = 30) consisted of 0.5% bupivacaine with epinephrine intraoperatively; for pain relief in the postoperative period (24 h), 0.25% bupivacaine with epinephrine was given every 3 h. General anesthesia (N = 30) consisted of controlled ventilation with N2O-O2 and intravenous fentanyl and pancuronium bromide; postoperatively, narcotic analgesics were given intramuscularly on demand for pain relief. Significantly lower frequencies were found following epidural anesthesia than after general anesthesia in deep venous thrombosis involving the popliteal and femoral veins (13% and 67%, respectively), deep venous thrombosis involving both calf and thigh veins (40% and 77%), and pulmonary embolism (10% and 33%). Possible explanations for these differences include increased circulation in the lower extremities, less tendency for intravascular clotting to occur, and more efficient fibrinolysis in association with continuous epidural anesthesia. The decrease in blood loss associated with epidural anesthesia with lower transfusion requirements also might play a role. Epidural analgesia prolonged into the postoperative period, in addition to other appropriate thromboprophylactic measures, should be of value in patients undergoing operations associated with a high risk of thromboembolic complications.

Aged↗
PubMed1981

Spinal pseudarthrosis with paraplegia in ankylosing spondylitis. A case report.

Destructive lesions of vertebral bodies in ankylosing spondylitis (AS) have for a long time been regarded as inflammatory changes, sometimes of tuberculous etiology. However, observations during recent years have established that these destructions in fact are non-unions after fractures. A case of spinal pseudarthrosis with paraplegia in a patient with advanced AS is presented. After combined anterior and posterior decompression as well as fusion using plate fixation, the neurological symptoms regressed completely and early mobilization of the patient was possible.

Bone Cysts↗