Reactions of sera from laboratory, domestic and wild animals in Africa with protein A and a recombinant chimeric protein AG

An ELISA was developed to determine the reactivity of peroxidase labelled Protein A and a recombinant Protein A + Protein G construct, to sera from a variety of laboratory, domestic and wild animals from Africa. There was variability in the binding capacity of sera from individuals of the same species, but four groups could be recognized. Sera from birds and crocodiles were at most weakly reactive with either Protein A or the chimeric construct. Sera from some domestic animals such as horse, goat and cat, and sera from some wild ungulates including buffalo, wildebeest, waterbuck and impala were reactive with Protein A, but reacted to a much greater degree with the chimeric construct. Sera from larger wild animals such as elephant, rhinoceros and giraffe were strongly reactive with the chimeric protein and moderately reactive with Protein A. Sera from primates and dog, pig, guinea pig and rabbit reacted strongly with both proteins. Chimeric proteins that combine the IgG binding capacities of Protein A and Protein G can be used to detect immunoglobulin from a wide variety of African wild animal species. They may thus be of great value in seroepidemiological investigations of these animal populations.

Linkage of rheumatoid arthritis with HLA

OBJECTIVE

To determine whether HLA exerts a variable influence on the predisposition of siblings of probands with clinically mild and severe rheumatoid arthritis (RA).

METHOD

Calculation of crude and adjusted odds ratios for concordance rates in sibships sharing two, one and no HLA haplotypes with a proband with clinically mild and severe RA, and HLA haplotype sharing in multiply affected sibships in the same clinical groups.

RESULTS

Compared with a reference value of 1.0 in siblings sharing no HLA haplotypes with a proband with mild RA, siblings sharing two HLA haplotypes with a severely affected proband had a sibship concordance rate odds ratio of 9.7 (95% confidence interval 2.5 to 38.2). When adjusted for age, sex, and disease duration, the odds ratio was 7.6 (1.8 to 32.4). No other sibships showed concordance rates which were significantly higher than the reference group. HLA haplotype sharing in multiply affected sibships in which the proband had severe RA deviated significantly from random (two, one, and no HLA haplotypes shared: 53.3, 40, and 6.7%, respectively; expected 25, 50, and 25%), whereas in sibships of probands with mild RA they did not (14.6, 70.8, and 14.6%).

CONCLUSIONS

In the predisposition of siblings to RA, sharing HLA haplotypes with a proband is only important if the proband has severe RA. Mild RA is not genetically linked to the HLA region.

MRI hippocampal volumes and memory function before and after temporal lobectomy

We investigated the relationship between preoperative MRI hippocampal volumes and clinical neuropsychological memory test data obtained before and after temporal lobectomy and amygdalohippocampectomy for intractable epilepsy in 44 left (LTL) and 36 right (RTL) temporal lobectomy patients. In LTL patients, the difference (right minus left hippocampal volume) between hippocampal volumes (DHF) was significantly (p < 0.001) correlated (r = 0.61) with postoperative verbal memory change as measured by a delayed memory percent retention score from the Wechsler Memory Scale-Revised, Logical Memory subtest. DHF was also positively associated with postoperative memory for abstract geometric designs in LTL patients (r = 0.49, p < 0.005). Resection of a relatively nonatrophic left hippocampus was associated with poorer verbal and visual memory outcome. In RTL patients, larger right adjusted (for total intracranial volume) hippocampal volume was associated with decline in visual-spatial learning, but not memory, following surgery. MRI hippocampal volume data appear to provide meaningful information in evaluating the risk for memory impairment following temporal lobectomy.

Antibodies bound to nitrocellulose in acidic buffers retain biological activity

This report compares the binding of proteins to nitrocellulose membranes in acidic buffers (pH 2 and 3) with binding in neutral buffer (pH 7). Initially, similar amounts of antibodies and other proteins bound to the nitrocellulose membrane in both acidic and neutral buffers. However, the susceptibility of individual proteins to displacement (stripping) from the membrane by the milk blocking agent depended on the pH of the buffer used to bind the proteins to the membrane. Most proteins that bound to nitrocellulose in acidic buffers were relatively resistant to milk-stripping compared to proteins bound in pH 7 buffer. Acid-binding of proteins to nitrocellulose also decreased the amount of protein that was stripped from the nitrocellulose membrane when Tween 20 was included in the washing buffer. After correcting for the amount of antibody remaining on the membrane after the milk block, it was found that acid-bound antibodies were unchanged in biological activity when compared with the same antibodies bound at neutral pH. These results suggest that acid-binding of proteins could increase the sensitivity of nitrocellulose membrane assays that use milk and/or Tween 20.

Western blot and indirect fluorescent antibody testing for antibodies reactive with Ehrlichia canis in sera from apparently healthy dogs in Zimbabwe

Sera were collected from apparently healthy dogs in 3 major centres in Zimbabwe to establish the prevalence of antibodies reactive with Ehrlichia canis by indirect fluorescent antibody (IFA) testing at titres of 1/20 or greater. The overall seroprevalence was 42% (39/93) with dogs from Mutare (40%) and Harare (33%) having similar rates which were lower than those for Bulawayo (68%). The majority of the IFA positive dogs from Harare (67%) had no haematological or biochemical evidence of canine ehrlichiosis. Total protein, albumin and globulin values were determined in sera from blood collected from Bulawayo and Mutare and all values were within normal reference ranges. Western blot profiles of sera from dogs with IFA titres of greater than 1/160 were similar to those using sera from dogs experimentally infected with E. canis Oklahoma strain. Our results indicate that an organism which is antigenically very similar or identical to E. canis is present in Zimbabwe and that dogs are commonly exposed to this organism.

Intracranial parenchymal schwannoma. A clinicopathological and neuroimaging study of nine cases

The clinical, radiological, and pathological features of nine cases of intracranial parenchymal schwannoma are described. The clinical course in four patients 23 years of age or younger mirrored the indolent nature of this neoplasm. Imaging studies included computerized tomography in eight patients and magnetic resonance imaging in three. The lesions were well demarcated with only mild surrounding edema. Five tumors were deep within the temporoparieto-occipital region, three were in the cerebellum, and one lay peripherally in the parietal lobe. Over two-thirds of the nine tumors were either cystic (five) or contained areas of cystic degeneration (two). One lesion was frankly hemorrhagic. A variety of imaging characteristics and contrast enhancement patterns were observed, including those of a cyst with a mural nodule and peripheral enhancement. Of the four solid neoplasms, two enhanced homogeneously while the other two demonstrated heterogeneous enhancement. Six tumors were resected totally. The follow-up period ranging from 2 months to 2 years has shown no recurrences. Microscopically, immunohistochemically, and ultrastructurally, the tumors were indistinguishable from peripheral schwannomas. A possible mechanism underlying the histogenesis of these rare lesions is discussed. The importance of recognizing this tumor is stressed, particularly in younger patients, given its benign nature, radiological resemblance to other tumors such as pilocytic astrocytoma, and favorable response to resection.

Astrocytomas of the cerebellum. A comparative clinicopathologic study of pilocytic and diffuse astrocytomas

BACKGROUND

The majority of patients with astrocytomas of the cerebellum have an excellent prognosis; however, a small percentage of patients continue to do poorly. To clarify the clinical, pathologic, and treatment characteristics that determine prognosis and therapeutic recommendations, a large group of patients with astrocytic tumors of the cerebellum was reviewed and analyzed.

METHODS

A clinicopathologic analysis was performed of all patients undergoing initial operation for astrocytomas in the cerebellum between 1960 and 1984. Of the 132 patients, 105 patients had pilocytic astrocytomas and 27 had diffuse astrocytomas.

RESULTS

Multivariate analysis revealed that the division of pilocytic and diffuse histologic type was the most significant prognostic factor influencing survival. The 5-year, 10-year, and 20-year survival rates were 85%, 81%, and 79%, respectively, for patients with pilocytic astrocytomas and 7%, 7%, and 7%, respectively, for patients with diffuse astrocytomas (P < 0.001). Pilocytic astrocytomas occurred in a younger age group and were more commonly cystic and completely resected.

CONCLUSIONS

Astrocytomas of the cerebellum can be divided into two principal groups, the pilocytic and the diffuse astrocytomas, each of which has distinct clinical, pathologic, and prognostic characteristics.

The relationship of increased capillary filtration and bone formation

The effect of functional activity on bone formation and interstitial fluid space in a standardized tibial defect was measured in 19 dogs with one hind limb elevated and the other weight bearing and in 15 dogs bearing weight on all four legs. The interstitial fluid space (V(isf)) of the woven bone of the weight-bearing defect was larger than that in the elevated legs at seven and 14 days. By 28 days, this difference disappeared. In a third group of six dogs, medullary canal pressure was measured in the immobilized and weight-bearing tibias. The pressures were higher in the weight-bearing tibiae at two, three, four, and five days. Because the increase in V(isf) in the weight-bearing defects coincided with the onset of woven bone formation in the defects and an increase in medullary canal pressure, an increase in venous pressure could increase capillary pressure and capillary filtration. Such an increase in filtration might cause the larger V(isf) in the weight-bearing defects and better capillary perfusion of precursor cells of the osteoblast. A hypothesis is that increased fluid flow from increased capillary filtration might produce streaming potentials, a possible signal for increased cellular activity.

Tamoxifen reduces bone turnover and prevents lumbar spine and proximal femoral bone loss in early postmenopausal women

Although widely used for its anti-estrogen properties tamoxifen has estrogen like effects on a number of tissues including bone and liver. Previous studies suggest a preservation of lumbar spine density in postmenopausal women but the effect on the hip had not been addressed. To determine whether tamoxifen prevents bone loss in the early postmenopausal period bone mineral density at the lumbar spine and femoral neck was measured using dual energy X-ray absorptiometry at presentation and 6 monthly thereafter for 1 year in a prospective controlled study. Also indices of bone turnover, serum osteocalcin and urinary hydroxyproline excretion, were assessed. Fifteen early postmenopausal women with Stage I or II breast cancer treated with tamoxifen and 21 normal postmenopausal women were studied. Sex hormone binding globulin and antithrombin III levels in serum were also measured as indices of the hepatic estrogenic activity. Tamoxifen (20 mg daily) prevented bone loss at the femoral neck and lumbar spine. Median rates of change in bone mineral density (%/year) for the tamoxifen group were +0.09%/year in the lumbar spine and 1.4%/year in the femoral neck compared with -2.3%/year and -1.8%/year for the control group (P = 0.04 and 0.03, respectively). Tamoxifen resulted in a significant decrease in both serum osteocalcin and urinary hydroxyproline by 6 months of treatment and this effect persisted for the 12 months of observation. An increase in sex hormone binding globulin and a decline in antithrombin III levels was also observed. These data indicate that, in recently, postmenopausal women tamoxifen prevented bone loss at both the lumbar spine and femur and reduced bone turnover.

Pineal parenchymal tumors. Clinical, pathologic, and therapeutic aspects

BACKGROUND

Pineal parenchymal tumors are rare; therefore, only limited clinical data regarding their behavior is available. This study was performed to provide further information regarding the pathologic features, clinical behavior, and response to therapy of these tumors.

METHODS

This study includes data concerning 30 patients (15 male and 15 female patients) with pineal parenchymal tumors (PPT) diagnosed between 1939 and 1991. Based on gross and microscopic features, tumors were divided into four groups: pineocytomas (9); PPT with intermediate differentiation (4); mixed PPT exhibiting elements of both pineocytoma and pineoblastoma (2); and pineoblastomas (15). At the time of diagnosis, four patients had evidence of spinal seeding (two with pineoblastoma, two with PPT with intermediate differentiation). Twenty-two patients received radiation therapy (RT): 6 were treated to local fields, 7 to the whole brain, and 9 to the craniospinal axis.

RESULTS

For patients who received RT and had a minimum follow-up of 6 months, local failure occurred in one of four patients with pineocytomas, zero of four patients with PPT with intermediate differentiation, one of two with mixed PPT, and four of nine (44%) with pineoblastomas. In patients receiving > or = 50 Gy to the primary tumor, 0 of 12 had local failure compared with 6 of 7 (86%) patients receiving lesser doses. Leptomeningeal failure occurred in zero of four patients with pineocytomas, zero of four patients with PPT with intermediate differentiation, one of two with mixed PPT, and four of nine with pineoblastomas. All leptomeningeal failures occurred in patients with persistent primary tumor. Of the patients with seeding tumors (PPT other than pineocytomas) one of seven (14%) developed leptomeningeal failure when treated with craniospinal irradiation, compared with four of eight (50%) treated to lesser volumes. The projected 1-year, 3-year, and 5-year survival rates of patients with pineocytomas were 100%, 100%, and 67%, and were 88%, 78%, and 58% for those with the other forms of PPT, respectively.

CONCLUSIONS

RT recommendations are described in detail and include the use of doses of > or = 50 Gy to areas of gross disease and the administration of craniospinal irradiation in patients with tumors prone to seeding. Surgical, chemotherapeutic, and pathologic considerations are discussed.

Analysis of the external fixator pin-bone interface

External fixator pins were inserted into tibiae of dogs under four in vivo loading conditions to examine the mechanism of pin loosening. Pins were quantitatively measured for pin torque resistance, and the pin tracts were studied radiographically and histologically. The pins holding an unstable fracture had more gross pin loosening. Pins also may become loose under static loads. Radiographic lucency of 1 mm or more in the cortical bone around a pin was evidence of gross pin loosening. Histologic examination showed that tight pin tracts were characterized by a lack of bone remodeling. Loose pin tracts were characterized by extensive bone resorption and inflammatory infiltrates. Pin loosening can be detected radiographically. Pin insertion technique is important to improve the initial pin torque resistance to minimize pin loosening. Sixty-nine percent of pins with an initial torque resistance of less than 68 Ncm became grossly loose compared with only 9% of pins with an initial torque resistance greater than 68 Ncm, regardless of the experimental group. Unstable external fracture fixation is another important factor in producing pin loosening. Pins loaded under unstable fracture fixation had the highest incidence of gross loosening. When applying an external fixator, the fracture rigidity should be critically evaluated and, if necessary, protected weight bearing must be introduced initially to minimize pin loosening.

The relationship of quantitative epidermal growth factor receptor expression in non-small cell lung cancer to long term survival

Increased expression of epidermal growth factor receptor (EGFr) has been reported in non small cell lung cancers (NSCLC) when compared to normal lung. We have examined post-operative survival in 19 surgically treated patients with NSCLC who had full characterisation of EGFr on primary tumour membrane preparations from resection specimens. There were ten squamous, seven adeno and two large cell carcinomas. The median concentration of high affinity sites was 31 fmol per mg of protein (4-1532) and the median dissociation constant (Kd) of these high affinity sites was 2.3 x 10(-10) per mol (1.2-30 x 10(-10)). Seven patients survived over 5 years. Twelve patients died between 8.5 and 55 months from the time of surgery. When > 5 year survivors were compared to non-survivors there was no difference as regards tumour size or stage, or as regards age or sex. The survivors had a median concentration of high affinity EGFr sites of 16.1 fmol mg-1 protein compared to a median concentration of 68.6 fmol mg-1 protein in the non-survivors (P = 0.01 Wilcoxon test). No long term survivor had > 35 fmol mg-1 protein of receptor. Thus EGFr quantitation may give independent prognostic information in NSCLC and help to select patients for adjuvant therapy after surgery. These results need confirmation in a larger prospective study.

Selecting DNA fragments for mutation detection by temperature gradient gel electrophoresis: application to the p53 gene cDNA

Temperature gradient gel electrophoresis (TGGE) and related methods are widely employed to detect mutations in DNA fragments. DNA melting map calculations and GC clamps have been used to enhance the detection of mutations. While generally successful, these methods have not always revealed base changes within a DNA fragment. Previous work suggested that mutations are detected if they are in a DNA's first melting domain, and the melting domain is well separated from final strand dissociation. Two criteria from the DNA melting theory were established to determine when both of these conditions are met. The criteria involve calculating the derivative melting curve as well as the melting map of a DNA sequence. The approach was applied to the cDNA sequence of the human p53 gene. Mutations in the p53 gene are common in human cancers and are generally located in four 'hot spot' regions. Calculations indicated that three DNA fragments are needed to detect base substitutions in the four hot-spot regions. Predicted melting behavior was experimentally tested with eight single base substitutions distributed among the four hot-spot regions. All mutations tested behaved as predicted and were detected by vertical TGGE. Heteroduplex DNAs formed by melting and reannealing various ratios of wild type and mutant DNA fragments were also examined. Results indicated that point mutations can be detected by ethidium bromide staining from samples containing 10% mutant and 90% wild-type sequences.

Surgical treatment for epilepsy in cerebral tuberous sclerosis

Tuberous sclerosis (TS) is an autosomal dominant hamartiosis and hamartomatosis with variable expression that is commonly associated with medically intractable seizures. Patients with TS complex (TSC) frequently have multiple brain lesions that can give rise to seizure activity. We report 9 patients with TSC who underwent epilepsy surgery at the Mayo Clinic between 1986 and 1990. Surgical procedures performed included cortical resection (n = 2) and stereotaxic lesionectomy (n = 7). Neuropathologic diagnoses were cortical tubers (n = 7) and glioneural hamartomas (n = 2). Three of 9 patients had multifocal interictal scalp epileptiform EEG activity; however, ictal recordings identified the focus of seizure activity, which in all cases corresponded to a prominent neuroimaging abnormality. Our patients have been followed for 10-72 months (mean 35 months). Four patients are seizure-free with medication, 2 are seizure-free without medication, 2 had > 80% reduction in seizure frequency, and 1 experienced only an initial temporary reduction in seizure frequency. Postoperative EEG recordings showed absence of epileptiform abnormalities in the 5 patients who are seizure-free; the other 4 patients continue to have multifocal abnormalities. These data suggest that epilepsy surgery may be beneficial in selected patients with TSC despite multifocal EEG and neuroimaging abnormalities.

Oligodendrocyte injury is an early event in lesions of multiple sclerosis

The ultrastructural features of 11 stereotaxic brain biopsy specimens that demonstrated inflammatory primary demyelination consistent with acute multiple sclerosis were examined. Uniform widening of inner myelin lamellae (biphasic myelinopathy) and degeneration of inner glial loops ("dying-back" oligodendrogliopathy) were early pathologic abnormalities that antedated complete destruction of myelin sheaths. Perivascular inflammatory cells (lymphocytes, macrophages, and occasional plasma cells) were in intimate contact with degenerating myelin sheaths. The response of astrocytes was prominent, even in areas of minimal demyelination. Oligodendrocytes were morphologically preserved in early lesions but proliferated at the periphery of active lesions. Thinly myelinated axons indicative of central nervous system-type remyelination by oligodendrocytes were observed primarily at the edge of plaques. Disturbances of the myelinating function of oligodendrocytes--unaccompanied by death of these cells--may be among the earliest pathologic features in multiple sclerosis.

The immediate effects of smoking on gingival fluid flow

The aim of the present study was to examine the immediate effect of smoking a cigarette on gingival crevice fluid (GCF) flow-rate. The study involved 17 healthy volunteers (6 male, 11 female) aged 19-57 years (mean 34.5 years) who regularly smoked cigarettes. All were periodontally healthy. GCF was collected at the mesio-buccal aspects of the right and left maxillary 2nd premolar teeth, using filter-paper strips left in place for 3 min. Samples were taken at baseline and subsequently at 10 min intervals for 70 min. Each subject sham smoked an unlit standard cigarette for 7 min after the 20 min recording, and smoked the same cigarette for 7 min to within 1 cm of the filter, following the 40 min recording. The results showed that following sham smoking (30 min recording) GCF volume increased by a mean of 16.7% (p = 0.057), and following smoking (50 min recording) GCF volume increased by a mean of 89.7%, over the previous recording (p < 0.0001). The increase following smoking was greater than that following sham smoking (p < 0.0001). Flow-rate returned to near resting levels within the experimental period. The results indicate that smoking produces a marked transient increase in GCF flow-rate, which might reflect changes in blood flow known to be produced by nicotine.

A study of nutritional deficits of long-stay geriatric patients

Current information suggests that dietary intake of nutrients declines with age and that undernutrition in elderly long-stay hospital patients may be under-recognized. We undertook to describe the daily dietary intakes of a group of elderly long-stay hospital patients (n = 92) (group A), using 7-day weighed dietary records. The aim of the study was to determine the adequacy of the diet and investigate whether any differences existed in the intakes of the hospital patients. An assessment of nutritional status was carried out by anthropometry, haematology and biochemistry and was validated by comparison with two further groups: fit young subjects (n = 41) (group B) and fit community elderly subjects (n = 92) (group C). Men in group B had the highest mean values for mid-arm circumference, arm-muscle circumference, corrected arm-muscle area and arm-fat area while women in group A had the lowest mean values for all measured anthropometric indices. There were significant correlations between daily energy intake and anthropometry for men in groups B and C. In group A 68% had intakes < 2/3 recommended daily allowance for energy, 100% for vitamin D, E, B6, folic acid; 98% for magnesium and zinc; and 90% for retinol. Serum calcium and serum alkaline phosphatase were correlated with vitamin D intake in men in group A. There was no biochemical or haematological evidence of undernutrition in the three groups. Elderly long-stay hospital patients were grossly undernourished and their dietary intake did not satisfy basal metabolic demands, based on recommended daily allowances.

Quantitative MRI hippocampal volumes: association with onset and duration of epilepsy, and febrile convulsions in temporal lobectomy patients

The relationships between preoperatively acquired MRI-based hippocampal volumes (HV), seizure disorder onset and duration, and early childhood febrile convulsions were investigated retrospectively with data from 72 left and 56 right temporal lobectomy patients. Patients with lesional pathology and heterotopic abnormalities were excluded. Age at development of spontaneous seizures unprovoked by an acute illness defined age of seizure disorder onset. Age of onset was subtracted from age at neurosurgery to determine duration. MRI variables included in this study were the right and left HV divided by total intracranial volume (RAHV, LAHV), and the right-left hippocampal difference (DHF). Partial correlations were used to better isolate relationships with onset of recurrent seizures corrected for age at surgery, and age at neurosurgery corrected for age of recurrent seizure onset. Partial correlations between age at neurosurgery and volume were not significant in either group. LAHV (r = 0.42, P < 0.0003) and DHF (r = -0.49, P < 0.0001) were correlated with age of onset in the left lobectomy group. Correlations in the right lobectomy group were not significant. The presence of a febrile convulsion was associated with smaller LAHV (F(1,70) = 10.54, P < 0.002) and larger DHF (F(1,70) = 11.36, P < 0.002) in left temporal lobectomy patients. The presence of a febrile convulsion in the right temporal group was associated with a slightly smaller DHF (F(1,56) = 5.90, P < 0.02), and slightly smaller RAHV (F(1,56) = 4.49, P < 0.04). These data suggest that hippocampal atrophy remains stable over the duration of temporal lobe onset seizure disorders, and is associated with early onset of recurrent seizures in left temporal patients.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of topical flurbiprofen as an adjunct to non-surgical management of periodontal disease

Non-steroidal anti-inflammatory drugs (NSAIDs) have been used as systemic and topical preparations to control chronic periodontal disease in both animal and clinical human trials. Equivocal findings have failed to confirm whether any one NSAID is particularly efficacious, although flurbiprofen appears to be one of the most promising. 49 patients were allocated at baseline to test (25) and control (24) groups in a 12-month, controlled clinical trial. The groups were of similar age and sex distributions. During the first 3 months, both groups were given oral hygiene instruction and received scaling and root planning. The test patients were prescribed a 1% w/w flurbiprofen toothpaste to use 2 x daily for the entire 12 months. Control subjects were prescribed a placebo dentifrice. Plaque scores, bleeding scores, crevicular fluid flow, probing pocket depths and attachment levels were assessed at baseline and at 3, 6, 9 and 12 months. Radiographs were taken at baseline and 12 months using a modified intraoral, repositionable film holder. Both the flurbiprofen and placebo showed significant improvements in the clinical parameters over 12 months and there were no significant differences between the groups. Flurbiprofen-treated patients however, demonstrated a significantly greater proportion of sites (8.0%) with bone gain when compared to the placebo group (3.3%). There were no significant differences between the groups in the number of sites showing bone loss or no change. It is concluded that the 1% w/w flurbiprofen toothpaste exerts a small, yet significant effect on bone metabolism in the absence of any apparent effects on clinical parameters.

Resection of intraventricular tumors via a computer-assisted volumetric stereotactic approach

Intraventricular tumors present a major challenge for neurosurgeons because of their depth and the important structures around them. Between 1984 and 1991, we performed 60 computer-assisted volumetric stereotactic resection procedures in 58 patients with intraventricular tumors (30 patients with third ventricular tumors and 28 patients with lateral ventricular tumors). The pathological findings of the tumors were as follows: colloid cyst in 27, giant cell astrocytoma in 5, central neurocytoma in 4, pilocytic astrocytoma in 4, meningioma in 3, subependymoma in 3, metastatic tumor in 3, oligodendroglioma in 2, ependymoma in 2, and miscellaneous tumors in 5 patients. Most presenting symptoms were nonlocalized--headache or cognitive dysfunction. All third ventricular tumors were approached via a frontal trajectory, and lateral ventricular tumors were approached according to the site and shape of the lesion. Total resection was achieved in 55 procedures. Overall outcome was excellent in 45 cases, good (some deficit but independent) in 5, and poor (dependent) in 3 (memory impairment, 2 patients; visual field cut, 1 patient). Two patients (3.4%) died postoperatively (one had a postoperative thalamic hemorrhage and pulmonary embolus; one had a subdural hygroma). In follow-up, three patients died from the extension of a malignant tumor or from primary cancer. Permanent morbidity was seen in three cases (5%). The authors believe computer-assisted volumetric stereotaxis is useful in removing intraventricular tumors. This technique allows us to find a safe trajectory and to locate and separate the tumor margin from the surrounding vital structures.

Computed tomography and histologic limits in glial neoplasms: tumor types and selection for volumetric resection

Selective and accurate resection of any computed tomography (CT) or magnetic resonance imaging (MRI) defined intracranial volume is possible by employing imaging-based computer-assisted volumetric stereotactic methods. Although the target volume can be any intracranial lesion, volumetric resection techniques were most frequently applied to the most commonly referred intraaxial lesions: glial neoplasms located in eloquent brain regions. Requirements for understanding of glial neoplasms as target volumes prompted investigations of the three-dimensional spatial configuration of these lesions, their histologic margins, and the accuracy with which these margins could be detected on CT and MRI. Stereotactic serial biopsy studies have shown that glial neoplasms frequently comprise two elements: tumor tissue and isolated tumor cells which infiltrate brain parenchyma. The tumor tissue component of high grade gliomas is most accurately defined by the volume which exhibits contrast enhancement. However, tumor tissue in low grade (nonpilocytic) gliomas is usually indistinguishable from infiltrated parenchyma on CT and MRI; both are hypodense on CT and do not usually exhibit contrast enhancement. Stereotactic serial biopsy is the only reliable method by which CT hypodense tumor tissue can be differentiated from infiltrated parenchyma in low grade (nonpilocytic) astrocytomas, oligodendrogliomas, and mixed gliomas. Stereotactic volumetric resection of infiltrated parenchyma defined by CT/MRI is advisable only in nonessential brain regions. In eloquent brain areas, stereotactic resection is appropriate for the glial tumor tissue component of high grade glial neoplasms, pilocytic astrocytomas, and low grade CT hypodense gliomas in which a stereotactic serial biopsy procedure has confirmed tumor tissue only.

The role of the clinical microbiology laboratory in the management of Clostridium difficile-associated diarrhea

Nosocomial diarrhea due to infection with C. difficile is a major health care problem, causing 20% to 30% of institutionally acquired diarrhea and affecting up to 8% of hospitalized patients. The clinical microbiology laboratory should be able to provide both diagnostic and epidemiologic services for institutions where this disease occurs. Diagnostic testing includes culture for isolation of toxigenic C. difficile and detection of either toxin A or B from stool specimens. Epidemiologic services include providing appropriate media and specimen preparation for surveillance activities and performance of accurate typing of C. difficile strains when necessary to determine organism relatedness for development of effective infection control practices.