Hyaluronan enters keratinocytes by a novel endocytic route for catabolism

Hyaluronan synthesized in the epidermis has an exceptionally short half-life, indicative of its catabolism by epidermal keratinocytes. An intracellular pool of endogenously synthesized hyaluronan, from 1 to 20 fg/cell, inversely related to cell density, was observed in cultured rat epidermal keratinocytes. More than 80% of the intracellular hyaluronan was small (<90 kDa). Approximately 25% of newly synthesized hyaluronan was endocytosed by the keratinocytes and had a half-life of 2-3 h. A biotinylated aggrecan G(1) domain/link protein probe demonstrated hyaluronan in small vesicles of approximately 100 nm diameter close to the plasma membrane, and in large vesicles and multivesicular bodies up to 1300 nm diameter around the nucleus. Hyaluronan did not co-localize with markers of lysosomes. However, inhibition of lysosomal acidification with NH(4)Cl or chloroquine, or treating the cells with the hyaluronidase inhibitor apigenin increased intracellular hyaluronan staining, suggesting that it resided in prelysosomal endosomes. Competitive displacement of hyaluronan from surface receptors using hyaluronan decasaccharides, resulted in a rapid disappearance of this endosomal hyaluronan (t(12) approximately 5 min), indicating its transitory nature. The ultrastructure of the hyaluronan-containing vesicles, co-localization with marker proteins for different vesicle types, and application of specific uptake inhibitors demonstrated that the formation of hyaluronan-containing vesicles did not involve clathrin-coated pits or caveolae. Treatment of rat epidermal keratinocytes with the OX50 monoclonal antibody against the hyaluronan receptor CD44 increased endosomal hyaluronan. However, no CD44-hyaluronan co-localization was observed intracellularly unless endosomal trafficking was retarded by monensin, or cultivation at 20 degrees C, suggesting CD44 recycling. Rat epidermal keratinocytes thus internalize a large proportion of their newly synthesized hyaluronan into non-clathrin-coated endosomes in a receptor mediated way, and rapidly transport it to slower degradation in the endosomal/lysosomal system.

Disc herniation-related back pain impairs feed-forward control of paraspinal muscles

STUDY DESIGN

A comparative study of lumbar paraspinal muscle reflexes during sudden upper limb loading in healthy control subjects and patients with sciatica.

OBJECTIVES

To assess reflex activation of paraspinal muscles during sudden upper limb loading.

SUMMARY OF BACKGROUND DATA

Sudden upper limb loading and upper limb voluntary movements cause reflex activation of trunk muscles. A short latency response of approximately 50 msec of lumbar muscles has been observed before, but the reflexes have not been studied in patients with sciatica.

METHODS

The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface EMG from 20 patients selected for an operation as a result of disc herniation-related chronic low back pain and 15 back-healthy controls. Pain, disability, and depression scores were recorded.

RESULTS

Short latency response of paraspinal muscles for unexpected upper limb loading was similar in healthy controls and patients with sciatica in supported standing. During normal standing anticipation shortened the lumbar reflex latency in healthy controls but not among the patients.

CONCLUSIONS

The results provide evidence for impaired feed-forward control of lumbar muscles in patients with sciatica.

Comparative immunohistochemical study of group II (synovial-type) and group IV (cytosolic) phospholipases A2 in disc prolapse tissue

Phospholipase A2 (PLA2) has been suggested to be present in herniated disc tissue and it could possibly be involved in sciatica/ discogenic back pain mechanisms. In the present study the occurrence of two different phospholipase A2 enzymes, (1) low molecular weight (14 kDa) group II synovial-type (sPLA2) and (2) high molecular weight (85 kDa) group IV cytosolic (cPLA2), were compared. Fifty-three disc prolapses obtained at disc operations were analyzed by immunohistochemistry, using anti-human monoclonal antibodies to sPLA2 and cPLA2, respectively. Only cell-associated (disc cells, hyaline cartilage chondrocytes) sPLA2 and cPLA2 immunoreactivity could be observed. The results showed that sPLA2 was more common (25/53, 47%) than cPLA2 (13/53, 25%). sPLA2 and cPLA2 were simultaneously present in 13 of 53 samples (25%). However, both PLA2 enzymes were predominantly present in hyaline cartilage cells (sPLA2: 16/53, cPLA2: 5/53), being less commonly observed in disc cells (sPLA2: 6/53, cPLA2: 3/53). In addition, three samples for sPLA2 and two samples for cPLA2 exhibited immunoreactivity in cartilage and disc cells simultaneously. sPLA2 was observed in no other locations, but in 3 of 53 samples cPLA2 was observed more diffusely in areas of granulation tissue, possibly in macrophages. No gender- or age-related dependence for either type of PLA2 enzyme immunoreactivity could be observed. Neither did their occurrence relate to clinical data such as straight leg raising or neurological deficit. The results do not support a major role for either of the two disc-cell-associated PLA2s in disc pathophysiology. For both enzymes, the major pool appears to reside in cartilage tissue cells, presumably in dislodged end-plate fragments. Disc cells are apparently unlikely candidates for major PLA2 storage.

Regional cerebral blood flow in aneurysmal subarachnoid hemorrhage: single photon emission tomography evaluation of endovascular versus surgical treatment

Since February 1995, 59 patients with recent aneurysmal SAH have been randomised in our study program, either for surgical aneurysm clipping or for endovascular treatment with Guglielmi detachable coils, to compare the safety and long-term efficacy of these methods. Patients with expansive haematomas or those in a moribund state were excluded, as well as those with aneurysms unsuitable for treatment with both methods. We used single photon emission tomography (SPET) to compare regional cerebral blood flow (rCBF) in surgically and in endovascularly-treated patients. In a sub-study presented in this paper, we analysed the data of patients in Grade I-III (Hunt & Hess) with anterior circulation aneurysms (n = 21). When changes between the pre- and post-treatment rCBF were compared, the surgically treated group showed a tendency towards improved rCBF (change in different vascular territories varied from +4% to +12%) while the endovascularly-treated group showed no consistent change (changes varied from -3% to +6%). There was, however, no significant statistical difference between the changes in the groups. Our results are preliminary, but they suggest that endovascular treatment of anterior circulation aneurysms may not have any advantage over surgical treatment in respect to disturbances in the rCBF.

Dissecting aneurysms of all four cervicocranial arteries in fibromuscular dysplasia: treatment with self-expanding endovascular stents, coil embolization, and surgical ligation

A patient with cervicocranial fibromuscular dysplasia (FMD) presented with subarachnoid hemorrhage. A ruptured dissecting distal vertebral artery aneurysm required clip ligation of the parent artery; a contralateral dissecting proximal vertebral aneurysm was occluded with detachable coils. Progressive dissecting, extracranial aneurysms of the internal carotid artery were treated with self-expanding stents. Subsequent angiography and intravascular sonography revealed patent stents, a smooth luminal surface, and total occlusion of the aneurysm. Clinical outcome was excellent.

Lumbar disc herniations in children: a long-term clinical and magnetic resonance imaging follow-up study

To determine the long-term outcome of 12 youthful patients with lumbar disc herniation, who, at the time of surgery, were 15 years old and younger (mean age at operation 14.3 years), we assessed their current clinical condition (mean follow-up time 6 years) with a questionnaire inquiring about symptoms and disability, and radiologically with an MRI of the lumbar spine. Clinically, only five patients (40%) were totally asymptomatic and seven patients (60%) had recurring symptoms, both and disability. On MRI, seven patients (60%) had persistent stenosing changes at the operated disc levels and eight patients (65%) also had disc degeneration at other lumbar levels. Despite the symptoms and quite severe radiological findings, the long-term outcome was assessed as good or moderate in eleven patients (90%). As far as comparisons are reasonable, our results appear somewhat less favourable than those in two previous paediatric series, but they agree with those in two recent large series of adults.

Lumbar spinal stenosis: a matched-pair study of operated and non-operated patients

The prevailing opinion seems to accept that the natural course of lumbar spinal stenosis is one of progressive worsening, and that only surgery can check this development. In fact, the choice of treatment for lumbar spinal stenosis is still an open question. The aim of this study was to compare in the matched-pair format the outcome of surgically and non-surgically treated patients with lumbar spinal stenosis. The surgically treated group consisted of 496 patients who were operated on during the period 1974-1987 and 440 of whom were re-examined an average of 4.1 years after surgery. The non-surgically treated group consisted of 57 patients who were treated conservatively during the period 1980-1987 and were re-examined an average of 4.3 years after the start of treatment. The matching criteria were sex, age, myelographic findings, major symptom and duration of symptoms. We were able to form 54 similar matched-pairs from the surgically and non-surgically treated patients. Subjective disability was assessed using the Oswestry questionnaire and functional status was evaluated during the clinical examination. For statistical analysis the McNemar test and the paired Student's t-test were used. The overall results showed no statistical difference in outcome between the matched-pair groups, but the operated men fared significantly better than the non-operated men. The functional status was very good in both groups and for both sexes. In conclusion, conservative treatment of lumbar spinal stenosis should be considered for the patients with moderate stenosis. Controlled, prospective and randomized trials are needed to clarify better the choice of treatment in patients with lumbar stenosis.

Inhibitory activity of the equine infectious anemia virus major 5' splice site in the absence of Rev

The major 5' splice site of equine infectious anemia virus (EIAV) conforms to the consensus 5' splice site in eight consecutive positions and is located immediately upstream of the gag AUG. Our results show that the presence of this 5' splice site on the EIAV gag mRNA decreases Gag production 30- to 60-fold. This is caused by inefficient nuclear mRNA export and inefficient mRNA utilization. Inhibition could be overcome by providing human immunodeficiency virus type 1 Rev/Rev-responsive element, human T-cell leukemia virus type 1 Rex/Rex-responsive element, or simian retrovirus type 1 constitutive transport element. In addition, inhibition could be abolished by introducing single point mutations in the 5' splice site or by moving the 5' splice site away from its natural position immediately upstream of the gag AUG. This demonstrates that both maintenance of a perfect consensus 5' splice site and its proper location on the mRNA are important for inhibitory activity of the EIAV major 5' splice site.

Early surgery improves the cure of aneurysm-induced oculomotor palsy

BACKGROUND

Aneurysm of the internal carotid-posterior communicating artery (ICA-PCoA) is the most frequent cause of sudden unilateral oculomotor palsy. Timely surgery for the aneurysm is the most important factor for third nerve recovery.

METHODS

We scrutinized the world literature with nearly one thousand cases of isolated unilateral oculomotor palsy caused by intracranial aneurysms and treated with surgery. Only those reports (one-third of all) in which the time interval between onset of oculomotor palsy and surgery could be determined were included. We treated 1314 patients with cerebral aneurysms (183 = 14% with ICA-PCoA aneurysms) from our catchment area in Eastern Finland during years 1977-1992. Twenty-eight patients having oculomotor palsy caused by ICA-PCoA aneurysm had surgery as soon as the diagnosis was made.

RESULTS

Eight of 9 patients operated within three days (0-3) and 4 of 6 patients operated on within 4 to 6 days the onset of oculomotor palsy had complete recovery of their third nerve function, in contrast to only 4 of 13 patients operated on later. Especially those operated on more than four weeks later had a dismal outcome: only 1 of 6 had complete recovery.

CONCLUSIONS

We recommend immediate admission and acute or early surgery for aneurysm-induced third nerve palsy, preferably within 3 days, to avoid functionally and cosmetically invalidizing disability.

The effect of prior back surgery on surgical outcome in patients operated on for lumbar spinal stenosis. A matched-pair study

It has been widely observed that the outcome after repeat lumbar surgery is rarely comparable to that of primary surgery. In particular, the results of repeat surgery for lumbar spinal stenosis (LSS) have not been favourable. We used a matched-pair format in an attempt to decrease the confounding factors so as to determine as exactly as possible the effect of prior back surgery on the LSS patients' surgical outcome. The matching criteria were sex, age, myelographic findings, major symptom, and duration of symptoms. From one group of 251 patients without prior back surgery (SO patients) and another of fifty-three patients with one preceding back operation (RS patients), forty-one similar matched patients pairs (one SO and one RS-patient) were formed. There were 8 female and 33 male pairs. The mean age of the SO patients was 51.6 and of the RS patient 51.4 years, and the mean follow-up time was 4.6 and 4.4 years. The assessment of outcome was based on a subjective disability questionnaire. The SO patients fared significantly better than the RS patients (32.1 versus 41.3, P = 0.026). A short time interval between operations in the RS patients had a worsening effect on outcome, but this trend was not significant. We concluded that one preceding back operation had a worsening effect on the outcome of patients operated on for LSS. As a whole, the results of RS patients were unfavourable. The proper time for achieving good surgical results in LSS patients is the initial operation.

Shunt-dependent hydrocephalus after subarachnoid haemorrhage and aneurysm surgery: timing of surgery is not a risk factor

Early hydrocephalus is a risk factor of shunt-dependent late hydrocephalus (SDHC). In the CT era 1980-1990 we had 835 consecutive patients operated on because of aneurysm and subarachnoid haemorrhage (SAH); 294 had an early hydrocephalus and 67 finally required a shunt. There were 14 patients with normal early CT and SDHC, in all 81 patients needed a shunt (10%). Patients with shunt did worse, they were older (53 vs 49) than the non-shunted group and there was a female preponderance. Pre-operative Grade correlated significantly with the need for a shunt operation; no one in Grade I developed SDHC, incidence in Grades III and IV was high (18% and 10%, respectively). Location was important; in vertebrobasilar area 28% and in anterior communicating area 14% but in middle cerebral area only 4% of the patients had SDHC. The amount of cisternal bleeding correlated significantly with SDHC; in 155 patients with non detectable or minimal cisternal blood only one developed SDHC, with severe cisternal bleeding the incidence was 16%. Ventricular bleeding increased the risk of SDHC, but intracerebral haematoma did not. Timing of surgery had no correlation with the risk of SDHC. Postoperative complications, haematomas and infections increased the risk of late SDHC. Delayed ischaemia correlated with the risk, but so did the treatment with nimodipine. Severe bleeding was the common predictor for the risk of SDHC. Location of the bleeding and postoperative problems are the other major causes. Outcome is, however, not so gloomy; 54% of patients with SDHC are independent one year later.

One-year outcome in early aneurysm surgery: a 14 years experience

In a consecutive series of 1150 patients with cerebral aneurysms diagnosed in our department by angiography or autopsy between the years 1977-1990, 1007 patients underwent definitive operative treatment of their aneurysms mainly by early surgery. More than half (55%) were operated on during the first three days after subarachnoid haemorrhage (SAH), and more than three quarters (77%) during the first week. The surgical mortality at 30 days was 9%; at one-year follow-up 13% had died. The total management mortality was 22%. The 618 patients presenting in Hunt and Hess Grades I-II had a 4% mortality, and 90% had an independent life at follow-up; 270 Grade III patients had a 19% mortality and 68% were independent. There were 99 patients operated on in Grades IV-V with a 46% mortality and 30% were independent. Age of the patient and size of the aneurysm were strongly related to outcome; however, many of the giant aneurysms were operated on as an emergency because of large intracerebral haematomas. Best results were obtained in the anterior communicating artery (ACA) area; the lowest rate of useful recoveries was in the vertebro-basilar artery (VBA) area (71%). Early surgery did not prevent delayed ischaemic deficits. During the first 72 hours patients in Grades I-III can be operated on safely with good results. The results in Grades IV-V are poor, and we suggest that only cases with large haematomas or considerable hydrocephalus or those improving should be operated on in the first days after SAH, with limited hopes of functional recovery.

Saccular aneurysms of the distal anterior cerebral artery and its branches

We report a series of 84 consecutive patients (41 women) with 92 distal anterior cerebral artery aneurysms (DACAA). All aneurysms were saccular. Four different locations of DACAAs were found: proximal, 5 aneurysms; frontobasal, 8; genu corporis callosi, 72; and distal, 7. Sixty-five patients presented with subarachnoid hemorrhage (SAH), the rest were incidental findings in patients with multiple aneurysms. Forty-five patients had single DACAAs. Multiple aneurysms (a total of 117) were found in 39 patients (46.4%), and DACAAs were responsible for SAH in 20 patients. Of the 65 patients with SAH, 54 underwent mainly early direct surgery, and 46 (85%) of these had good outcomes 1 year after surgery. Three patients remained severely disabled, and five patients (9%) died. All of the poor surgical results were obtained in patients with severe preoperative deficits. Exact measurements of DACAA sizes and necks were smaller than those of cerebral aneurysms in other locations. Aside from localization, microsurgery of these aneurysms presented no special difficulties, as compared with surgery of aneurysms in other locations.

Impaired utilization of exogenous amino acids after surgery for subarachnoid haemorrhage

We studied the metabolic response to acute aneurysm surgery and its modification by parenteral nutrition. Forty-eight patients receiving perioperative corticosteroid treatment were randomly assigned to receive glucose alone (7.2 kcal/day, D5W + C), glucose and a conventional amino acid solution (7.2 kcal/day and 0.15 gN/day, CAA + C) or glucose and branched chain amino acid enriched solution (7.2 kcal/day and 0.14 gN/day, BCAA + C). Twenty patients without corticosteroid treatment received either glucose alone (7.2 kcal/day, D5W) or glucose and a conventional amino acid solution (7.2 kcal/day and 0.14 gN/day, CAA). Poor nitrogen utilization was indicated by strongly negative nitrogen balance in all groups and a failure of the infused amino acids to improve nitrogen balance. (Day 0; D5W + C: -9.3 +/- 3.6 g/day and CAA + C: -8.2 +/- 9.7 g/day vs CAA: -2.6 +/- 4.9 g/day, p less than 0.05, Day 1; D5W + C: -14.9 +/- 9 g/day vs CAA: -7.7 +/- 6.5 g/day, p less than 0.05, MANOVA). We conclude that subarachnoid haemorrhage and its surgical treatment induce a catabolic response and impaired utilization of exogenous nitrogen, further amplified by perioperative corticosteroids, which is in sharp contrast to the response to surgery not involving the central nervous system.