Idiopathic syringomyelia and the importance of occult arachnoid webs, pouches and cysts

Syringomyelia is the condition in which longitudinal cavities are found within the spinal cord. The use of drainage procedures has been widely practised with good short term results. However, the long-term results in some large series have been less favourable. There are many associated conditions and in most forms a blockage to the normal flow of CSF, either at the foramen magnum or in the spinal canal, can be identified. Most surgeons would now direct their efforts to the establishment of normal CSF flow rather than a shunting procedure. In a certain group of patients, even with the advent of sophisticated MRI, no associated abnormality or CSF block is easily identified. This type of syringomyelia is often termed idiopathic. We report 10 patients with symptomatic syringomyelia without readily recognized predisposing factors. In eight patients preoperative myelography revealed a block to the flow of contrast compatible with subarachnoid obstruction. Eight patients underwent laminectomy and division of the obstructing arachnoid webs. Five experienced good improvement and three only moderate improvement. Two of the patients underwent syrinx shunting procedures only, which resulted in a worsening of their symptoms. At operation one patient was found to have an arachnoid cyst. We believe that patients with idiopathic symptomatic syringomyelia may need myelography to identify such arachnoid abnormalities. Subsequent surgery should be directed at the establishment of normal CSF flow by laminectomy and excision of the offending lesion.

Univariate analysis of tsetse habitat in the common fly belt of southern Africa using climate and remotely sensed vegetation data

Tsetse are vectors of trypanosomes that cause diseases both in humans and livestock. Traditional tsetse surveys, using sampling methods such as Epsilon traps and black screen fly rounds, are often logistically difficult, costly and time-consuming. The distribution of tsetse, as revealed by such survey methods, is strongly influenced by environmental conditions, such as climate and vegetation cover, which may be readily mapped using satellite data. These data may be used to make predictions of the probable distribution of tsetse in unsurveyed areas by determining the environmental characteristics of areas of tsetse presence and absence in surveyed areas. The same methods may also be used to characterize differences between tsetse species and subspecies. In this paper we analyse the distribution of Glossina morsitans centralis, Glossina morsitans morsitans and Glossina pallidipes in southern Africa with respect to single environmental variables. For G.m.centralis the best predictions were made using the average NDVI (75% correct predictions; range > 0.37) and the average of the maximum temperature (70% correct predictions; 27.0-29.2 degrees C). For G.m.morsitans the best prediction was given by the maximum of the minimum temperature (84% correct predictions; range > 18.8 degrees C), and for G.pallidipes, also by the maximum of the minimum temperature (86% correct predictions; range > 19.6 degrees C). The following paper compares a range of multivariate techniques for making predictions about the distribution of these species in the same region.

Mapping tsetse habitat suitability in the common fly belt of southern Africa using multivariate analysis of climate and remotely sensed vegetation data

The distribution of Glossina morsitans centralis, Glossina morsitans morsitans and Glossina pallidipes are described in part of southern Africa, using a range of multivariate techniques applied to climate and remotely sensed vegetation data. Linear discriminant analysis is limited in its predictive power by the assumption of common covariances in the classes within multivariate environment space. Maximum likelihood classification is one of a variety of alternative methods that do not have this constraint, and produce a better prediction, particularly when a priori probabilities of presence and absence are taken into account. The best predictions are obtained when the habitat is subdivided, prior to classification, on the basis of a bimodality detected on the third component axis of a principal component analysis. The results of the predictions were good, particularly for G.m.centralis and G.m.morsitans, which gave overall correct predictions of 92.8% and 85.1%, with a Kappa index of agreement between the prediction and the training data of 0.7305 and 0.641 respectively. For G.pallidipes, 91.7% of predictions were correct but the value of Kappa was only 0.549. Very clear differences are demonstrated between the habitats of the two subspecies G.m.centralis and G.m.morsitans.

Cost effectiveness of day and inpatient psychiatric treatment: results of a randomised controlled trial

OBJECTIVE

To compare direct and indirect costs of day and inpatient treatment of acute psychiatric illness.

DESIGN

Randomised controlled trial with outcome and costs assessed over 12 months after the date of admission.

SETTING

Teaching hospital in an inner city area.

SUBJECTS

179 patients with acute psychiatric illness referred for admission who were suitable for random allocation to day hospital or inpatient treatment. 77 (43%) patients had schizophrenia.

INTERVENTIONS

Routine inpatient or day hospital treatment.

MAIN OUTCOME MEASURES

Direct and indirect costs over 12 months, clinical symptoms, social functioning, and burden on relatives over the follow up period.

RESULTS

Clinical and social outcomes were similar at 12 months, except that inpatients improved significantly faster than day patients and burden on relatives was significantly less in the day hospital group at one year. Median direct costs to the hospital were 1923 pounds (95% confidence interval 750 pounds to 3174 pounds) per patient less for day hospital treatment than inpatient treatment. Indirect costs were greater for day patients; when these were included, overall day hospital treatment was 2165 pounds cheaper than inpatient treatment (95% confidence interval of median difference 737 pounds to 3593 pounds). Including costs to informants when appropriate meant that day hospital treatment was 1994 pounds per patient cheaper (95% confidence interval 600 pounds to 3543 pounds).

CONCLUSIONS

Day patient treatment is cheaper for the 30-40% of potential admissions that can be treated in this way. Carers of day hospital patients may bear additional costs. Carers of all patients with acute psychiatric illness are often themselves severely distressed at the time of admission, but day hospital treatment leads to less burden on carers in the long term.

Quiescence, cycling, and turnover in the primitive hematopoietic stem cell compartment

Continuous oral bromodeoxyuridine (BrdU) administration was used for the non-invasive measurement of the in vivo cell cycling characteristics of hematopoietic stem and progenitor cell populations of increasing maturity, isolated on the basis of their relative levels of Rhodamine 123 (Rh) and Hoechst 33342 (Ho) fluorescence. The results showed that whereas primitive hematopoietic stem cells (PHSCs) are hierarchically ordered on the basis of quiescence, the most primitive of these, characterized by their Rh/Ho(dull) phenotype and their capacity for long-term hematopoietic reconstitution, are not dormant, but cycle slowly in normal steady-state bone marrow (BM). Cell cycle analysis showed that 30 +/- 7% of Rh/Ho(dull) PHSCs had cycled and incorporated BrdU following continuous administration over 1 week, whereas 60 +/- 14% and 89 +/- 3% of these cells were BrdU positive at 4 and 12 weeks, respectively. Linear regression analysis of these data showed that Rh/Ho(dull) PHSCs cycle with an average turnover time of 4.3 weeks (30 days), and a t1/2 (time to 50% cycled) of 2.75 weeks (19 days).

Regulation of large calcium-activated potassium channels by protein phosphatase 2A

Vasodilating agents induce relaxation of mesangial cells, in part through cGMP-mediated activation of large calcium-activated potassium channels (BKCa). Normally quiescent in cell-attached patches, the response of BKCa to nitric oxide, atrial natriuretic peptide, and dibutyryl cGMP (Bt2cGMP) is characterized by a biphasic increase and then decrease ("rundown") in open probability. Using the patch-clamp method in conjunction with phosphatase inhibitors, we investigated whether the run-down phase was the result of dephosphorylation by an endogenous protein phosphatase. In cell-attached patches, cantharidic acid (500 nM), okadaic acid (100 nM), and calyculin A (100 nM), nondiscriminant inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A) at these concentrations, caused a significantly greater and sustained response of BKCa to Bt2cGMP. Within 2 min, the response of BKCa to the combination of cantharidic acid and Bt2cGMP was greater than the response to these agents added separately. Incubation of mesangial cells with okadaic acid for 20 min at a concentration (5 nM) specific for PP2A increased the basal open probability of BKCa and completely inhibited rundown after activation by Bt2cGMP. Incubation with calyculin A (10 nM), a more potent inhibitor of PP1, did not affect BKCa activity. In inside-out patches, Bt2cGMP plus MgATP caused a sustained activation of BKCa that was inhibited by exogenous PP2A but not PP1. It is concluded that either BKCa or a tightly associated regulator of BKCa is a common substrate for endogenous cGMP-activated protein kinase, which activates BKCa, and PP2A, which inactivates BKCa, in human mesangial cells.

Bleaching of a discoloured non-vital tooth: use of a sodium perborate/water paste as the bleaching agent

Bleaching materials containing hydrogen peroxide have been used successfully for the treatment of discoloured non-vital teeth; however, their use has occasionally been associated with external root resorption. Some evidence exists that sodium perborate mixed with water is as effective as sodium perborate mixed with hydrogen peroxide. A case is presented which supports this and a step-by-step technique is described.

Longitudinal analysis of quantitative virologic measures in human immunodeficiency virus-infected subjects with > or = 400 CD4 lymphocytes: implications for applying measurements to individual patients. National Institute of Allergy and Infectious Diseases AIDS Vaccine Evaluation Group

The natural variability of quantitative virologic measures among human immunodeficiency virus (HIV) type 1-infected persons was prospectively studied in 29 untreated persons with >600 CD4 cells/microL and in 15 persons receiving zidovudine monotherapy who had 400-550 CD4 cells/microL at study entry. Cell- and plasma-associated infectious HIV-1, provirus, and virion RNA were determined monthly as were numbers of CD4 and CD8 cells. HIV-1 replication varied widely among subjects with similar CD4 cell counts. The within-individual variability was significantly less than the variability between subjects for all virologic measures. Plasma virion HIV-1 RNA levels had the least variability. A mathematical model was devised to assess whether a potential therapeutic intervention significantly alters peripheral HIV-1 load. The model indicated that three measurements of plasma RNA would be outside the 95th percentile for the expected change in an individual due to natural variability. This approach can be used to accurately assess a therapeutic intervention among persons with low plasma HIV-1 titers.

Assessment of behavioral symptoms in community-dwelling dementia patients

The authors compared the CERAD Behavior Rating Scale for Dementia (CBRSD) with the Cohen-Mansfield Agitation Inventory (CMAI) for their ability to detect behavioral symptoms in community-dwelling dementia patients with mild-to-moderate global impairment. Both instruments were administered to caregivers of 33 cognitively impaired patients seen in a dementia clinic at initial evaluation or follow-up visit. Endorsement of a higher percentage of items on the CBRSD than the CMAI suggests greater sensitivity of this instrument to the behavioral symptoms seen in community-dwelling patients. There was good correlation between the number of items endorsed on both scales but not between subscales of the CMAI and factors of the CBRSD that appeared related to agitation. Thus, the CBRSD and CMAI both seem to measure behaviors that occur in dementia patients, but the CBRSD's two agitation-related factors do not appear to measure agitation as defined by the CMAI.

A critical appraisal of pediculated omental graft transposition in progressive spinal cord failure

A critical review of patients who had pediculated omental grafting for progressive spinal cord failure was performed in order to assess the impact of this procedure on the natural history of the spinal cord function after spinal cord injury. Ten patients were reviewed; all had complete or partial paraplegia. Mean age at injury was 29.1 years. There was an average interval of 9.7 years between injury and onset of progressive worsening of symptoms, and 5.6 years between onset of such symptoms and diagnosis. Average follow-up was 24.5 months. Five patients underwent omental grafting as primary surgical treatment whereas the other five had earlier procedures. One patient died on the postoperative period. Significant morbidity was also observed. All the surviving patients were asked to score themselves by answering a questionnaire exploring the effect of surgery in limb function and performance on activities of daily living. Only two patients improved following the procedure. Two others remained unchanged, while the remaining six continued to deteriorate. There was no difference in clinical outcome between the primary surgery group and the ones that had had previous procedures. Delayed omental grafting done as tried in this clinic did not seem to improve the prognosis of the injured cord and was associated with significant morbidity.

Immunity against measles in school-aged children: implications for measles revaccination strategies

Measles serum antibody levels were determined by plaque reduction neutralization (PRN) test in 1,075 children in the age bracket of 5 to 17 years who received a single dose of measles-mumps-rubella (MMR II) vaccine at one year of age. Of these, 297 children (28%) had measles PRN titres < 120 which may not be protective against measles infection. The proportion of susceptible children by age ranged from 14 to 35%; however, there was no consistent age-dependent trend in susceptibility rates. The study data indicate the decline in protective immunity occurs before five years of age, and the proportion susceptible increases only slightly thereafter. This supports the current move towards a two-dose immunization strategy in the control and elimination of measles, with the second dose being given before school entry. The present data also underscore the need to consider a mass catch-up immunization program in the interim to prevent potential outbreaks of measles in school settings. The combination of the above approaches, if implemented as soon as possible, can potentially eliminate indigenous measles in Canada by the year 2000, the target date set by the Pan American Health Organization.

Combination of SCF, IL-6, IL-3, and GM-CSF increases the mitotic index in short term bone marrow cultures from acute promyelocytic leukemia (APL) patients

Acute promyelocytic leukemia (APL) is characterized cytogenetically by the presence of a reciprocal translocation between chromosomes 15 and 17 [t(15;17)(q22-q24;q11-q21)] in the bone marrow cells in the majority of patients. Cytogenetic evaluation of bone marrow cultures from patients with APL is often technically difficult, due to frequent difficult marrow aspiration and the suboptimal quality of cytogenetic preparations. This has important implications for the cytogenetic detection of residual disease. This study examined the proliferative ability of the recombinant human growth factors-stem cell factor (SCF), interleukin-6 (IL-6), interleukin-3 (IL-3), and granulocyte macrophage-colony stimulating factor (GM-CSF)-to determine if they would provide a consistent improvement over the standard cytogenetic culturing techniques in terms of mitotic index (MI). In all cases, the MI of the growth factor stimulated cultures showed a considerably higher (3.5-198 fold) and statistically significant (p < 0.01) increase compared to the unstimulated cultures. We conclude that the use of recombinant human growth factors is potentially an effective way of increasing the MI in bone marrow cultures from APL patients for the purposes of diagnosis and residual disease detection.

Affinity purification of biologically active and inactive forms of recombinant human protein C produced in porcine mammary gland

Recombinant human protein C (rhPC) secreted in the milk of transgenic pigs was studied. Transgenes having different regulatory elements of the murine milk protein, whey acidic protein, were used with cDNA and genomic human protein C (hPC) DNA sequences to obtain lower and higher expressing animals. The cDNA pigs had a range of expression of about 0.1-0.5 g/l milk. Two different genomic hPC pig lines have expressed 0.3 and 1-2 g/l, respectively. The rhPC was first purified at yields greater than 60 per cent using a monoclonal antibody (mAb) to the activation site on the heavy chain of hPC. Subsequent immunopurification with a calcium-dependent mAb directed to the gamma-carboxyglutamic acid domain of the light chain of hPC was used to fractionate a population having a higher specific anticoagulant activity in vitro. The higher percentages of Ca(2+)-dependent conformers isolated from the total rhPC by immunopurification correlated well with higher specific activity and lower expression. A rate limitation in gamma-carboxylation of rhPC was clearly identified for the higher expressing animals. Thus, transgenic animals with high expression levels of complex recombinant proteins produced a lower percentage of biologically active protein.

Preoperative anesthesia and postoperative considerations in laser resurfacing

This article details patient selection, preoperative preparation, and postoperative considerations for conducting UltraPulse (Coherent Medical, Palo Alto, CA) CO2 laser resurfacing. The authors share their more than 3 years experience with more than 1,000 patients to help physicians perform this technique, choose optimal treatment parameters, and select appropriate patients for treatment. Methods to decrease postlaser adverse sequelae are discussed. Particular emphasis is placed on the minimization of postoperative infections. An extensive section on anesthesia techniques is also provided.

Management and outcome of posttraumatic syringomyelia

Traumatic paraplegia is the most common cause of nonhindbrain-related syringomyelia. Fifty-seven patients with a mean age of 34.3 years at presentation were treated at the Midland Centre for Neurosurgery and Neurology between 1973 and 1993. A variety of treatment strategies have been used over the years, including syringosubarachnoid and syringopleural shunts, spinal cord transection, and pedicled omental graft transposition. More recently decompressive laminectomy, subarachnoid space reconstruction and formation of surgical meningocele have been used. A total of 81 operations were performed in these patients, 69 of them at the Syringomyelia Clinic. Combinations of strategies were often chosen; the use of one strategy such as drainage did not preclude another such as transection or augmentation of the cerebrospinal fluid pathways. The overall postoperative complication rate was 12%. Problems specific to the operation type included dislodged, blocked, and infected drains (10 patients). Acute gastric dilation was seen following pedicled omental graft (one patient). At 6 years only 49% of the drains inserted still functioned. A higher than expected rate of cervical spondylotic myelopathy has been noted. Two patients developed Charcot's joints. Thirty-six patients were asked to score themselves with regard to limb function and performance of daily living activities and 30% reported improvement, particularly ion arm function. Since the use of magnetic resonance imaging has become widespread, it has become apparent that decompressive laminectomy with subarachnoid space reconstruction is effective in controlling the syrinx cavity. In complete paraplegia, spinal cord transection is an effective alternative. Pedicled omental grafting was associated with poor outcome and an increased complication rate and has been abandoned.

The effect of domestic water filters on water fluoride content

The effect of filtration on water fluoride level was investigated in a study using commercially available filters. Testing was carried out in London (low fluoride), Braintree (optimum fluoride, naturally occurring) and Birmingham (optimum fluoride, artificially adjusted). It was found that none of the filters removed fluoride. In Birmingham, but not in either Braintree or London, there was a small, clinically insignificant increase in fluoride levels with filtration using two of the five filters. It is concluded that the water filtration systems tested will not affect the advantage offered by optimum water fluoride levels. Fluoride dietary supplements should not be prescribed for children living in optimal fluoride areas, irrespective of whether they use household filters.