Vertebral blood flow and bone mineral density during long-term corticosteroid treatment: An experimental study in immature pigs

STUDY DESIGN

Bone mineral density and regional blood flow were measured in pigs during long-term methylprednisolone treatment.

OBJECTIVES

To investigate possible changes in bone mineral density and vertebral blood flow during long-term glucocorticoid treatment.

SUMMARY OF BACKGROUND DATA

Steroid-induced vertebral osteonecrosis preferentially involves endplates and adjacent cancellous bone. The precise etiology of vertebral osteonecrosis during long-term glucocorticoid treatment is unknown.

METHODS

Twenty-four 10-week-old female Danish landrace sister pigs from 12 litters were treated in two groups. Twelve animals received oral methylprednisolone for 3 months at a daily dose of 100 mg. The 12 sister pigs received no steroid treatment and served as controls. Regional blood blow was measured by means of microspheres in predefined regions of the C6, T11, and L6 vertebrae. In vitro DEXA scanning of the L2-L4 vertebra was performed to assess bone mineral density.

RESULTS

Vertebral cancellous bone and endplate regional blood flow were decreased in the C6 and L6 vertebrae among corticosteroid-treated pigs compared with that of controls.- Width-adjusted lumbar vertebral bone mineral density (g/cm3) was unchanged, whereas projectional lumbar vertebral bone mineral density (g/cm2) was decreased in corticosteroid-treated pigs.

CONCLUSIONS

Long-term methylprednisolone treatment decreases vertebral bone blood flow mainly in cancellous bone and endplates. This may be an important factor in the pathogenesis of osteonecrosis secondary to glucocorticoid treatment. Lumbar vertebral bone mineral density was unchanged in growing pigs on long-term glucocorticoid treatment when expressed as volumetric bone density. The effect of glucocorticoid treatment on vertebral bone mineral density appears to depend on whether it is expressed as projectional (g/cm2) or volumetric bone mineral density (g/cm3). Vertebral and longbone growth was reduced during methylprednisolone treatment.

Effect of moderate exercise on blood flow in the gastrointestinal tract in trained conscious miniature swine

AIM

To examine how moderate exercise affects the blood flow in the gastrointestinal tract.

MATERIALS AND METHODS

Twelve miniature swine weighing 38-43 kg were used. All animals were trained on a cardiac exercise treadmill. Blood flow measurements were done on conscious animals using labeled microspheres with a diameter of 16.5 +/- 0.1 (SD) microm. The first flow was measured while the animal was awake and resting, the second flow after 15 min of exercise, the third flow after 30 min of rest.

RESULTS

Flow in the oesophagus at rest was 19.5 +/- 1.3 (SEM) ml/min/100 g. During exercise the flow decreased to 13.3 +/- 1.2 (SEM) ml/min/100 g (ns). After 30 min of rest the flow was 9.9 +/- 1.2 (SEM) ml/min/100 g (p < 0.05 when comparing the flow before and after exercise). Flow in the cardia at rest was 23.1 +/- 1.3 (SEM) ml/min/100 g. During exercise the flow decreased to 14.0 +/- 1.2 (SEM) ml/min/100 g (p < 0.05). After 30 min of rest the flow was 15.0 +/- 1.2 (SEM) ml/min/100 g. Flow in the pylorus at rest was 38.9 +/- 1.1 (SEM) ml/min/100 g. During exercise the flow decreased to 24.6 +/- 1.1 (SEM) ml/min/100 g (p < 0.01). After 30 min of rest the flow was 26.9 +/- 1.2 (SEM) ml/min/100 g. Blood flow in the small and large intestine was mainly unaffected by moderate exercise.

CONCLUSION

Under moderate exercise, blood flow in the upper part of the gastrointestinal tract declines while it is mainly unaffected in the duodenum, small and large intestine.

Decrease in enkephalin levels in psoriatic lesions after calcipotriol and mometasone furoate treatment

BACKGROUND

Enkephalins are opioid peptides that can modulate immune responses and inflammatory processes. Furthermore, they inhibit keratinocyte proliferation/differentiation in vitro. Previously, we have shown that enkephalins are present in increased amounts in lesional psoriasis.

OBJECTIVE

To determine the effect of topical treatment with the vitamin D analogue calcipotriol and the corticosteroid mometasone furoate on the level of methionine-enkephalin (enk) in psoriatic lesions.

METHODS

Twelve psoriatic patients were treated with calcipotriol and mometasone furoate for 14 days without or with hydrocolloid occlusion. Keratome biopsies were obtained from treated and untreated skin, and the extracted enk was quantified by radioimmunoassay. Furthermore, punch biopsies were obtained for immunohistochemical analysis.

RESULTS

Clinically, both calcipotriol and mometasone furoate improved psoriasis to the same degree, the effects being more pronounced after occlusion. Histologically, treatment with mometasone furoate without occlusion decreased both the epidermal thickness/parakeratosis and the number of dermal immunocompetent cells (CD3- and CD68-positive cells). In contrast, treatment with calcipotriol without occlusion reduced the epidermal thickness and the degree of parakeratosis but decreased the number of CD3- and CD68-positive cells only slightly. The mean enk level was decreased by 26 and 86% by calcipotriol without and with occlusion and by 16 and 63% by mometasone furoate without and with occlusion, respectively. The decreases in the enk levels corresponded to the degree of clinical improvement but not to the histological changes.

CONCLUSION

The increased levels of enk in psoriatic lesions are reduced in parallel with the clinical improvement induced by a topical vitamin D analogue and a corticosteroid. Because enkephalins can modulate epidermal differentiation and inflammatory processes, the findings indicate that enkephalins may play a role in the pathogenesis of psoriasis.

Recombinant bone morphogenetic protein-7 as an intracorporal bone growth stimulator in unstable thoracolumbar burst fractures in humans: preliminary results

The study presented here is a pilot study in five patients with unstable thoracolumbar spine fractures treated with transpedicular OP-1 transplantation, short segment instrumentation and posterolateral fusion. Recombinant bone morphogenetic protein-7 in combination with a collagen carrier, also referred to as OP-1, has demonstrated ability to induce healing in long-bone segmental defects in dogs, rabbits and monkeys and to induce successful posterolateral spinal fusion in dogs without need for autogenous bone graft. Furthermore OP-1 has been demonstrated to be effective as a bone graft substitute when performing the PLIF maneuver in a sheep model. Five patients with single-level unstable burst fracture and no neurological impairment were treated with intracorporal OP-1 transplantation, posterior fixation (USS) and posterolateral fusion. One patient with osteomalacia and an L2 burst fracture had an additional intracorporal transplantation performed proximal to the instrumented segment, i.e. OP-1 into T 12 and autogenous bone into T 11. Follow-up time was 12-18 months. On serial radiographs, Cobb and kyphotic angles, as well as anterior, middle and posterior column heights, were measured. Serial CT scans were performed to determine the bone mineral density at fracture level. In one case, radiographic and CT evaluation after 3 and 6 months showed severe resorption at the site of transplantation, but after 12 months, new bone had started to fill in at the area of resorption. In all cases there was loss of correction with regard to anterior and middle column height and sagittal balance at the latest follow-up. These preliminary results regarding OP-1 as a bone graft substitute and stimulator of new bone formation have been disappointing, as the OP-1 device in this study was not capable of inducing an early sufficient structural bone support. There are indications to suggest that OP-1 application to a fracture site in humans might result in detrimental enhanced bone resorption as a primary event.

A review of ceramic coatings for implant fixation

The present series of eight studies was performed in order to investigate the effect of various clinically relevant factors on bone ingrowth in relation to hydroxyapatite (HA) and titanium-alloy (Ti) coating when subjected to pathological and mechanical conditions mimicking the clinical situation. HA- and Ti-coated implants were inserted into the femoral condyles of mature dogs and one study was performed on humans. The observation period ranged from 4 to 52 weeks, and the results were evaluated by mechanical push-out testing, histomorphometric analysis, polarized light microscopy, UV fluorescence microscopy and collagen analysis. There were no complications related to the operative procedures, and all dogs were killed according to the original time schedule. Two studies focused on in vivo mechanisms and factors influencing resorption of HA coating. The overall conclusions from these studies are that HA coatings do resorb in vivo, that micromotion accelerates resorption, and that resorbed HA is partly replaced by newly formed bone, suggesting that implants fixation is durable. The other studies focused on the significance of mechanical stabilization and loading conditions of the implant immediately after surgery. From these studies, it can be concluded that HA-coating has a positive effect on bone-implant fixation in various situations, i.e., under stable loaded conditions and under unstable mechanical conditions. The most striking effect of HA coating was that it enhanced bone growth across a gap around the implant both during stable and unstable mechanical conditions; it even converted a motion-induced fibrous membrane to bony anchorage.

Reperfusion pattern of the immature femoral head after critical ischemia: a microsphere study in pigs

The topographic reperfusion pattern of the femoral head after critical ischemia has not yet been investigated. We determined the blood flow of the porcine hip regions with the femoral head epiphysis divided into 24 subregions by the tracer microsphere technique. Blood flow was measured under steady-state conditions, at the end of a 6-hour increase in intracapsular hip joint pressure to 250 mm Hg, and 4 hours after release of the joint tamponade. Total femoral head epiphyseal blood flow decreased with ischemia and regained steady-state perfusion after tamponade. The reperfusion pattern of the femoral head epiphysis appeared identical with that of the steady state before ischemia. However, 2 of the 11 experimental epiphyses remained ischemic in the reperfusion phase. We conclude that hip joint tamponade above the arterial pressure level for 6 hours causes global ischemia in the femoral head epiphysis in the immature pig, without regional differences in reperfusion, and that reperfusion occurs at a level like that of the steady state before ischemia.

Growth, developmental stability and immune response in juvenile Japanese quails (Coturnix coturnix japonica)

Stresses are environmental factors which restrict growth or cause a potentially adverse change in an organism. The exposure of developing organisms to environmental stresses may have several physiological consequences including a decrease in immunocompetence. However, mounting an immune response against a foreign antigen may in itself constitute a cost for developing organisms. This cost has potentially long-term consequences for adult function and fitness. This study examines the growth and developmental stability of Japanese quail++ chicks challenged by three non-pathogenic antigens: sheep red blood cells, which assess T-cell-dependent immune responses, and Mycoplasma synoviae and Newcastle disease virus, which assess T-cell-independent responses. Increases in both body mass and wing length were significantly reduced in antigen-challenged birds compared to control birds. Fluctuating asymmetry (FA) in the masses of primary feathers increased from the innermost (1) to the outermost (10) position on the wing. In addition, antigen challenge by M. synoviae and sheep red blood cells was associated with an increase in FA. The cell-mediated response measured by reaction to phytohaemagglutinin was significantly depressed in M. synoviae-challenged birds. White blood cell counts, except for monocytes, were elevated in response to all three antigen treatments. Total plasma protein and haematocrit also differed between treatments but exhibited no clear relationship to antigen challenge. Immune responses clearly impose a stress on developing chicks. Additional research will be required to determine the long-term consequences of developmental stress and assess the selective forces that influence the strength of the immune responses of chicks.

Functional outcome after partial reduction and 360 degree fusion in grade III-V spondylolisthesis in adolescent and adult patients

Reduction of high-grade spondylolisthesis is a surgically demanding procedure, which has been reported to incur a relatively high risk of neurologic damage, pseudoarthrosis, and other complications. The aim of this study was to evaluate the radiographic and functional outcome in spondylolisthesis grade III-V, surgically treated with posterior decompression, L4- or L5-S1 CD instrumentation, partial reduction, and posterolateral fusion followed by anterior interbody fusion L5-S1 ad modum Kellogg-Speed. Thirteen patients, mean age 23.8 (range, 11-33) years were followed for mean 28.5 (range, 19-52) months. The anterior slip, lumbosacral angle, sagittal rotation angle and L4/SI angle were significantly improved from preoperatively to follow-up. No patients had neurologic, vascular, thromboembolic, or lung complications. Twelve patients reported a better or unchanged (3 patients) physical and emotional status. At follow-up, 10 patients were in full-time jobs or back to school. The method was safe and provided a stable rigid fixation with partial reduction of the deformity and a satisfactory functional outcome.

Mortality and causes of death among Danish medical doctors 1973-1992

BACKGROUND

To examine the mortality pattern of Danish doctors for the period 1973-1992.

METHODS

A historical prospective cohort study based on the membership register of the Danish Medical Association. The study population consisted of 21,943 medical doctors, 6012 of whom were women. The doctors' cause-specific mortality was compared with that of the general population.

RESULTS

The study covered about 277,000 person-years. A total of 2387 deaths occurred from 1 January 1973 to 31 December 1992. The doctors' mortality was lower than that of the general population. Both sexes showed a standardized mortality ratio (SMR) below one for cancer, circulatory diseases and other natural causes. Mortality due to lung cancer was particularly low. The SMR for suicide was significantly increased, 1.6 for males (95% CI: 1.4-1.9) and 1.7 for females (95% CI: 1.1-2.5). The suicide rate was increased, in particular because of an increased number of suicides by poisoning. In addition female doctors displayed a relatively high mortality due to accidents and other types of violent death.

CONCLUSIONS

Compared with the general population the doctors' mortality was low, but the mortality from external causes was increased, mainly due to an excess number of suicides.

Chorioamniotic membranes constitute a competent barrier to group b streptococcus in vitro

OBJECTIVE

To study the penetration of group B streptococcus (GBS) through human chorioamniotic membranes in vitro.

STUDY DESIGN

Chorioamniotic membranes from seventeen healthy women were mounted onto glass cylinders and placed in tissue culture trays constituting a two-compartment system with a maternal compartment internally and a fetal compartment externally. GBS from healthy pregnant women and from newborn babies with sepsis were added to the maternal compartment at densities from 10(7) to 10(9) colony forming units (cfu) per ml.

RESULTS

Irrespective of inoculum density, GBS was not recovered from the fetal compartment within a 20 h incubation period. By histology, micro-colonies of GBS were found on the maternal surface after 8 h, but invasion of the morphologically intact membranes was not observed. A five log reduction in cfu occurred in the maternal compartment with amnion when GBS were suspended in saline.

CONCLUSION

In this in vitro model the membranes appear to constitute an effective barrier against ascending infection.

[The effect of pedicle screw instrumentation on posterolateral spinal fusion. A prospective, randomized study with a two-year follow-up]

The aim was to evaluate the effect of supplementary pedicle screw fixation (Cotrel-Dubousset [CD]) in posterolateral lumbar spinal fusion. The study comprises 130 patients undergoing lumbar or lumbosacral fusion for spondyloisthesis grades I-II or degenerative segmental instability conditions. The patients were randomly allocated for no instrumentation (n = 66) or CD instrumentation (n = 64) in posterolateral lumbar fusion. A 97.7% follow-up was achieved. There were no significant differences between the two groups concerning fusion rates assessed by X-ray or functional outcomes assessed by Dallas Pain Questionnaire. The global patient satisfaction was 82% in the instrumented group versus 74% in the noninstrumented group. Instrumentation increased both operation time, blood loss, and early re-operation rates significantly. A high patient satisfaction was found in both groups. However, the results from this study do not justify the general use of pedicle screw fixation alone as an adjunct to posterolateral lumbar fusion.

Can autologous bone culture predict spinal fusion capacity?

The capacity of the individual patient to initiate osteoblast proliferation as a predictor for successful lumbar spinal fusion has not yet been reported. The objectives of this study were, first, to analyze the relationship between in vitro osteoblast proliferation and clinical bony fusion in the individual patient in order to predict the fusion outcome and, second, to measure the effect of preoperative tobacco smoking on osteoblast proliferation. Sixty-one patients (mean age 46 years) underwent posterolateral lumbar fusion in the period 1994-1995. Thirty-eight patients received CD pedicle screw implants and 23 received posterolateral fusions alone. During surgery, autogenous iliac bone was harvested and 1 g of trabecular bone without blood or bone marrow was then isolated for cell culturing. The cultures were classified as excellent (confluence within 4 weeks), good (confluence between 4 and 6 weeks) and poor (no or poor growth). Spine fusion was evaluated by two independent observers from plain anterior-posterior, lateral, and flexion/extension radiographs taken 1 year postoperatively, and the functional outcome was measured by the Dallas Pain Questionnaire (DPQ). Twenty-three patients had excellent, 19 good, and 19 poor in vitro osteoblast proliferation. Bony fusion was obtained in 77% of patients: 83% in the CD instrumentation group and 70% in the non-instrumentation group (NS). There was no significant correlation between osteoblast proliferation and spinal fusion or functional outcomes when analyzing the CD instrumentation and non-instrumentation groups together or separately. Elderly patients had a significantly poorer osteoblast proliferation than younger patients (P < 0.008). Preoperative tobacco consumption had no discernible effect on osteoblast proliferation, and no correlation between smoking and fusion was found. Further refinement of autologous osteoblast culturing may provide a biological tool for selection of patients who require biological enhancement of their bone fusion capacity. The poorer osteoblast proliferation related to advanced age supports the important negative biological influence of age on bony fusion. However, with more sensitive testing and better discrimination, other results are possible - or can in any event not be excluded.

Increased levels of enkephalin following natural sunlight (combined with salt water bathing at the Dead Sea) and ultraviolet A irradiation

The opioid peptides enkephalins have been shown to modulate inflammatory responses and keratinocyte proliferation and differentiation. Furthermore, increased levels of enkephalin are present in psoriatic lesions. The purpose of the present study was to determine the effect of natural sunlight combined with salt water bathing in the Dead Sea on the methionine-enkephalin (e.n.k.) level in psoriatic skin. Ten patients were treated at the Dead Sea for 4 weeks, and keratotome biopsies were obtained before and after treatment. The amount of enkephalin extracted from the biopsies was measured by radioimmunoassay. Treatment at the Dead Sea resulted in a complete clinical clearance of psoriasis, and immunohistochemical stainings of lesional skin showed that the treatment decreased both epidermal thickness/parakeratosis and the dermal infiltration of CD3- and CD68-positive cells, although the number of CD3- and CD68-positive cells became normal in only two of the 10 cases. However, there was only a slight decrease in the mean enk levels (21%). Furthermore, the level of enk was high in non-lesional psoriatic skin after treatment at the Dead Sea, and immunostaining showed that, in some patients, the treatment induced a mild epidermal hyperplasia and a dermal infiltration of CD3- and CD68-positive cells. Enkephalin-like immunoreactivity was detected in the cytoplasm of both epidermal keratinocytes and dermal infiltrating cells. To determine whether the relatively high skin enk levels after treatment at the Dead Sea was caused by ultraviolet (UV) radiation, normal volunteers were exposed to a single dose of UVA and UVB (2 minimal erythema doses). UVA, but not UVB, irradiation stimulated the mean enk level in the irradiated skin by about sixfold. Furthermore, multiple whole-body UVA irradiations not only resulted in increased skin levels of enk, but also in increased plasma levels. In conclusion, natural sunlight combined with salt water bathing cleared psoriasis without causing a significant decrease in lesional enk levels. Furthermore, non-lesional enk levels were increased. These findings may be the result of a direct stimulatory effect of UVA irradiation on enk formation in the skin. It is possible that the increased circulating levels of enk after UV exposure may contribute to the beneficial effects of UVA irradiation.

[Reperfusion capacity of the femur head after ischemia--an experimental study]

PURPOSE OF THE STUDY

The aim of this study was to evaluate bone blood flow of the proximal femur during experimentally induced ischemia and to document the ability of epiphyseal and metaphyseal reperfusion.

METHODS

11 pigs (danish landrace) were used to investigate the effect of tamponade by increased joint pressure (Dextran 70) on the perfusion of the femoral head. Additional 8 pigs were used as control. The blood flow in the hip joint was studied by means of the microsphere technique. The flow was determined before, during and after intraarticular pressure increase. With the "radioactive tracer microsphere"-method the blood flow of the epiphysis, metaphysis and proximal femoral corticalis could be measured.

RESULTS

In the epiphyseal femoral head the initial blood flow rate, 11.7 ml/min/100 g, was not significant different from that of the control side (11.1 ml/min/100 g). The blood flow decreased in the ischemic phase to 1.8 ml/min/100 g followed by reperfusion to 13.5 ml/min/100 g (p < 0.01). The bone blood flow of reperfusion was not significant different from that of the initial blood flow rate but in 2 cases a "blow out" of the epiphyseal bone blood flow was seen. The proximal femoral metaphysis showed the highest of the measured intraosseous flow rates (17.9 resp. 23.3 ml/min/100 g). During ischemia and reperfusion of the epiphysis bone blood flow of the metaphysis remained the same. The proximal femoral corticalis showed the lowest of the measured intraosseous flow rates. The operated (10.1 ml/min/100 g) and contralateral hip side (11.7 ml/min/100 g) showed no significant differences in the initial blood flow rate. During ischemia and reperfusion the blood flow of the proximal corticalis showed no significant difference to the initial blood flow corresponding to the metaphysis.

CONCLUSIONS

Our study demonstrates disturbances of the circulation of different regions of the femoral head during intraarticular pressure increase and following pressure decrease of the growing pig. 2 "blow outs" document a vulnerable proximal epiphysis already after a 6-hour ischemia. Additional minor "bone quality" in cases of certain diseases (kidney transplantation, leukemia) and special administration of drugs (corticosteroids) seem to create an additional vulnerability of the proximal femoral head. The experiment proves to be a reliable model for decreasing the blood flow of the growing epiphysis temporarily and to document the beginning of normal reperfusion. With this model it is possible to examine the vulnerability of the epiphyseal perfusion after different diseases and under the influence of different medication.

1997 Volvo Award winner in clinical studies. The effect of pedicle screw instrumentation on functional outcome and fusion rates in posterolateral lumbar spinal fusion: a prospective, randomized clinical study

STUDY DESIGN

A prospective randomized clinical study.

OBJECTIVES

To evaluate supplementary pedicle screw fixation (Cotrel-Dubousset) in posterolateral lumbar spinal fusion.

SUMMARY OF BACKGROUND DATA

The rationale behind lumbar fusion is to eliminate pathologic motion to relieve pain. To improve fusion rates and to allow reduction, a rigid transpedicular screw fixation may be beneficial, but the positive effect of this may be counter-balanced by an increase in complications.

METHODS

The inclusion criteria were severe, chronic low back pain from spondylolisthesis Grades 1 and 2 or from primary or secondary degenerative segmental instability. One hundred thirty patients were randomly allocated to receive no instrumentation (n = 66) or Cotrel-Dubousset instrumentation (n = 64) in posterolateral lumbar fusion. Variables were registered at the time of surgery and at 1 and 2 years after surgery.

RESULTS

Follow-up was achieved in 97.7% of the patients. Fusion rates deduced from plain radiographs were not significantly different between instrumented and noninstrumented groups. The functional outcome assessed by the Dallas Pain Questionnaire improved significantly in both groups, and there were no significant differences in results between the two groups, except for significantly better (P < 0.06) functional outcome in relation to daily activities in the instrumented group when neural decompression had been performed. The global patients' satisfaction was 82% in the instrumented group versus 74% in the noninstrumented group (not significant). Fixation of instrumentation increased operation time, blood loss, and early reoperation rate significantly. Patients experienced only a few minor postoperative complications; none were major. Two infections appeared in the Cotrel-Dubousset group. Significant symptoms from misplacement of pedicle screws were seen in 4.8% of the instrumented patients.

CONCLUSIONS

Lumbar posterolateral fusion with pedicle screw fixation increases the operation time, blood loss, and reoperation rate, and leads to a significant risk of nerve injury. The functional outcome improves significantly with high patient satisfaction, with or without instrumentation. No significant differences were observed between the two groups in functional outcome and fusion rate. The only gain in functional outcome from instrumentation was found in the daily activity category in patients with supplementary neural decompression. The results of this study do not justify the general use of pedicle screw fixation alone as an adjunct to posterolateral lumbar fusion.

Spinal cord and nerve root blood flow in acute double level spinal stenosis

STUDY DESIGN

Twenty-four pigs were randomized into three groups of eight pigs; a control group with 0% stenosis, a 25% stenosis group, and a 50% stenosis group. A fourth 75% stenosis group was added when results of the randomized experiment had been analyzed. Blood flow of the spinal cord and nerve roots and spinal evoked potentials were determined before and 1 hour after induction of the spinal stenoses.

OBJECTIVES

To study the acute effects of different degrees of spinal stenosis on neural tissue blood flow and spinal evoked potentials.

SUMMARY OF BACKGROUND DATA

Spinal cord dysfunction may be caused by vascular impairment or mechanical injury to neural tissue. Experimental double level compression of the cauda equina causes reversible nerve root edema, stasis, blood flow decrease, and compromised neural function. The vascular pathophysiology after spinal cord trauma was studied previously, and both increased and decreased neural tissue blood flow have been reported.

METHODS

Two level spinal stenosis was introduced by placement of stenosing bands around the dural sac at L4 and L6. Neurologic function was monitored by sensory and motor evoked potentials. Regional blood flow (RBF) was measured in the stenotic segments between the bands and other regions of neural tissue by radioactive microspheres before and after induction of stenosis.

RESULTS

Regional blood flow increased in the stenotic segments after 0% sham stenosis. Analysis of variance revealed no differences in RBF between the three randomized groups under comparable conditions of 0% stenosis. However, the RBF level of the added 75% group was lower than that of the other three groups. By comparison of RBF within groups before and after stenosis, no decrease in RBF was found between the stenosing bands in any of the groups. Fifty percent stenosis changed the amplitude of evoked potentials in half of the animals. Seventy-five percent stenosis caused severe changes in evoked potentials in 7 of 8 animals.

CONCLUSIONS

Blood supply of the spinal cord and nerve roots in the segments between two central stenoses is preserved immediately after stenosis introduction by way of the segmental nerve pathway, even if nerve conduction is impaired.

[Mortality and cause of death among Danish physicians 1973-1992]

This study examines mortality rates of Danish doctors and describes pattern and causes of death for the period 1973-1992. The study comprises 21,943 medical doctors, 6012 of whom were women. At the end of 1992 there were 2387 recorded deaths. The doctors had lower mortality rates than the general population. A significant lower mortality was seen for male medical specialists compared to general practitioners. A gender-difference was seen among the youngest doctors with the female doctors suffering a considerably higher mortality than the male doctors did. Both sexes showed SMR below unity for cancer, circulatory diseases and other natural causes. Mortality due to lung cancer was particularly low. The suicide mortality was increased for both sexes, in particular because of an increased number of suicides by poisoning. Compared with the general population the doctors' mortality was low, but the mortality from external causes was increased, mainly due to an excess number of suicides.

Vasorelaxation in isolated bone arteries. Vasoactive intestinal peptide, substance P, calcitonin gene-related peptide, and bradykinin studied in pigs

We assessed the effects of vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), substance P (SP), and bradykinin in arteries (diameter approximately 230 microns) isolated from cancellous bone from pigs. Arterial segments (2 mm long) were mounted on a myograph for measurement of isometric force development. After submaximal precontraction with norepinephrine, VIP (10(-10)-10(-7) M), CGRP (10(-11)-10(-7) M), SP (10(-6) M), and bradykinin (10(-11)-10(-6) M) were added. 44 arterial segments (23 pigs) were investigated. VIP-, CGRP-, and bradykinin induced a concentration-dependent vasorelaxation, while SP mediated a transient relaxation. After mechanical removal of the endothelium, the effects of SP and bradykinin were completely abolished, while the relaxation to CGRP was still pronounced. This indicates that the effects of SP and bradykinin are mediated by the endothelium, while CGRP mainly mediates relaxation by a direct effect on vascular smooth muscle cells. The relaxations to CGRP and bradykinin were still significant after inhibition of nitric oxide synthase with 10(-4) M N omega-nitro-L-arginine (L-NNA) and inhibition of prostaglandin synthesis with 10(-5) M indomethacin, indicating the existence of an alternative vasorelaxing pathway. Our findings support the theory of a vasoregulatory role of neuropeptides in bone.

A cohort mortality study of foundry workers

Since the 1970s, hygienic improvements have led to a reduction in the level of airborne pollutants in Danish foundries. This mortality study reflects the exposure situation prior to 1970, and the findings may be used as a baseline for future evaluations of the preventive impact of reduced exposure. Mortality data were derived from a historical cohort study in which 3,056 foundry workers were compared with 43,024 workers employed in other industries. The foundry workers' life-long risk of dying from pneumoconioses averaged 2% and the corresponding standardized mortality ratio (SMR) equaled 7,368 (95% confidence interval (95% CI): 4,029-12,363). Excess mortality was also seen for chronic bronchitis and emphysema (SMR = 132, 95% CI: 98-185). Nonsignificant increases were seen for buccal cancer, stomach cancer, colon cancer, and urothelial cancer. In conclusion, Danish foundry workers exposed prior to 1970 seem to suffer an excess risk of devastating lung disease of occupational origin.

Pyospermia and preterm, prelabor, rupture of membranes

OBJECTIVES

To investigate the possible association between presence of clinically unrecognized, specific genito-urinary tract microorganisms in men and preterm, prelabor rupture of membranes (PPROM) in their spouses.

STUDY DESIGN

Case control study. Eleven couples with PPROM were enrolled in the case group and 18 couples with normal pregnancies in the control group. For each man, samples of urine and semen were collected and a urethra swab was obtained. Microbiological assessment included, for each woman, cultures from vagina/cervix, urine and placenta. A smear from the vagina was obtained.

RESULTS

In the case group, pyospermia was found in three men. Two of these men, as well as their spouses, were Chlamydia trachomatis positive, and in the third man no microorganisms could be detected. None of the controls had pyospermia (p = 0.045). Among the eight cases without pyospermia one man and one women with Chlamydia trachomatis was found, but their spouses were negative. In the control group, no Chlamydia trachomatis was detected (p = 0.014). Among the women two cases and one control had positive culture of Group B streptococci (NS).

CONCLUSION

We suggest that the genital microflora of the man is associated with PPROM.

Microbiology of semen specimens from males attending a fertility clinic

The relationship between semen quality, pyospermia and bacteriology was studied in 201 semen specimens from male patients attending a fertility clinic. Semen quality parameters were within normal limits in 115 (57%) patients, slightly reduced in 60 (30%), and 26 (13%) had findings indicating reduced fertility. Twelve patients (6%) had pyospermia. In 182 patients, 552 microorganisms were detected, including Enterobacteriaceae (2.8%), Gardnerella vaginalis (9.6%), Chlamydia trachomatis (1.6%), Mycoplasma genitalium (0.9%), and Ureaplasma urealyticum (11.8%). Semen quality was neither related to occurrence of microorganisms nor pyospermia. However, pyospermia was associated with simultaneous growth of Gardnerella vaginalis and Ureaplasma urealyticum. The exact nature of this association could not be ascertained, in as far as the males were not questioned about urethritis symptoms.