Biofilm formation is a risk factor for mortality in patients with Candida albicans bloodstream infection-Scotland, 2012-2013

Bloodstream infections caused by Candida species remain a significant cause of morbidity and mortality in hospitalized patients. Biofilm formation by Candida species is an important virulence factor for disease pathogenesis. A prospective analysis of patients with Candida bloodstream infection (n = 217) in Scotland (2012–2013) was performed to assess the risk factors associated with patient mortality, in particular the impact of biofilm formation. Candida bloodstream isolates (n = 280) and clinical records for 157 patients were collected through 11 different health boards across Scotland. Biofilm formation by clinical isolates was assessed in vitro with standard biomass assays. The role of biofilm phenotype on treatment efficacy was also evaluated in vitro by treating preformed biofilms with fixed concentrations of different classes of antifungal. Available mortality data for 134 patients showed that the 30-day candidaemia case mortality rate was 41%, with predisposing factors including patient age and catheter removal. Multivariate Cox regression survival analysis for 42 patients showed a significantly higher mortality rate for Candida albicans infection than for Candida glabrata infection. Biofilm-forming ability was significantly associated with C. albicans mortality (34 patients). Finally, in vitro antifungal sensitivity testing showed that low biofilm formers and high biofilm formers were differentially affected by azoles and echinocandins, but not by polyenes. This study provides further evidence that the biofilm phenotype represents a significant clinical entity, and that isolates with this phenotype differentially respond to antifungal therapy in vitro. Collectively, these findings show that greater clinical understanding is required with respect to Candida biofilm infections, and the implications of isolate heterogeneity.

Instrumented assessment of test battery for physical capability using an accelerometer: a feasibility study

Recent work has identified subdomains (tests) of physical capability that are recommended for assessment of the healthy ageing phenotype (HAP). These include: postural control, locomotion, endurance, repeated sit-to-stand-to-sit and TUG. Current assessment methods lack sensitivity and are error prone due to their lack of consistency and heterogeneity of reported outcomes; instrumentation with body worn monitors provides a method to address these potential weaknesses. This work proposes the use of a single tri-axial accelerometer-based device with appropriate algorithms (referred to here as a body worn monitor, BWM) for the purposes of instrumented testing during physicality capability assessment. In this pilot study we present 14 BWM-based outcomes across the subdomains which include magnitude, frequency and spatio-temporal characteristics. Where possible, we compared BWM outcomes with manually recorded values and found no significant differences between locomotion and TUG tasks (p ≥ 0.319). Significant differences were found for the total distance walked during endurance (p = 0.037) and times for repeated sit-to-stand-to-sit transitions (p < 0.000). We identified reasons for differences and make recommendations for future testing. We were also able to quantify additional characteristics of postural control and gait which could be sensitive outcomes for future HAP assessment. Our findings demonstrate the feasibility of this method to enhance measurement of physical capacity. The methodology can also be applied to a wide variety of accelerometer-based monitors and is applicable to a range of intervention-based studies or pathological assessment.

iCap: Instrumented assessment of physical capability

•

Instrumented testing of five physical capability tasks with a single accelerometer.

•

Evaluated on a large cohort of older adults.

•

iCap provides robust quantitative data about physical capability.

•

iCap captures gait and postural control data known as sensitive to ageing/pathology.

•

Methodology may have practical utility in a wide range of surveys and studies.

Objectives

The aims of this study were to (i) investigate instrumented physical capability (iCap) as a valid method during a large study and (ii) determine whether iCap can provide important additional features of postural control and gait to categorise cohorts not previously possible with manual recordings.

Study design

Cross-sectional analysis involving instrumented testing on 74 adults who were recruited as part of a pilot intervention study; LiveWell. Participants wore a single accelerometer-based monitor (lower back) during standardised physical capability tests so that outcomes could be compared directly with manual recordings (stopwatch and measurement tape) made concurrently.

Main outcome measures

Time, distance, postural control and gait characteristics.

Results

Agreement between manual and iCap ranged from moderate to excellent (0.649–0.983) with mean differences between methods low and deemed acceptable. Additionally, iCap successfully quantified (i) postural control characteristics which showed sensitivity to distinguish between 5 variations of the standing balance test and (ii) 14 gait characteristics known to be sensitive to age/pathology.

Conclusions

Our findings show that iCap can provide robust quantitative data about physical capability during standardised tests while also providing sensitive (age/pathology) postural control and gait characteristics not previously quantifiable with manual recordings. The methodology which we propose may have practical utility in a wide range of clinical and public health surveys and studies, including intervention studies, where assessment could be undertaken within diverse settings. This will need to be tested in further validation studies in a wider range of settings.

Differential impairment of spatial location memory in Huntington's disease

OBJECTIVE

To determine whether a differential impairment of spatial memory exists in Huntington's disease (HD).

METHODS

Patients with HD and age matched neurologically normal subjects, as well as patients with Alzheimer's disease (AD) and Parkinson's disease (PD), learned the locations of nine items on a 3 x 3 grid over as many as 10 trials. Delayed recall of the items and their spatial locations was tested.

RESULTS

Patient with HD performed worse than normal subjects on all measures, and intermediate between AD and PD patients. However, they were the only subject group in whom delayed recall of spatial locations was poorer than delayed recall of object identity. This effect was independent of the severity of dementia.

CONCLUSIONS

HD patients have a differential impairment in memory for object-location information. This finding may relate to the involvement of the caudate nucleus, the primary site of pathology in HD, in corticostriatal circuits linking it with parietal association cortex. It is also consistent with views of the dorsal striatum as responsible for the acquisition over trials of specific place responses.

Infection of chick chorioallantoic membrane (CAM) as a model for invasive hyphal growth and pathogenesis of Candida albicans

We report the development of a simple model for assessing the ability of the fungal pathogen Candida albicans to invade the chorioallantoic membrane (CAM) of fertilized hens' eggs. Wild-type and mutant strains of C. albicans were inoculated onto CAM surfaces either as a liquid suspension or on a sterile filter disc. Invasion of the membrane led to death of the embryo due to damage of the CAM, which could be examined histologically to show cell distribution and morphology, and by RT-PCR for assessment of patterns of fungal gene expression in vivo. Prophylactic or co-administration of fluconazole with the inoculum protected the embryo from infection. Secretory aspartyl protease (Sap) mutant strains with reported attenuation of virulence were virulent in the CAM model. However, a C. albicans strain with mutations in two transcription factors Efg1 and Cph1 was unable to form hyphae on the CAM or to penetrate it. The chick CAM, therefore, represents an experimentally tractable and inexpensive alternative to rodent or tissue culture-based invasion models, and can be used to investigate fungal pathogenesis and the genetic regulation of infection and membrane penetration of C. albicans.

End-Organ reinnervation does not prevent axonal degeneration in nerve allografts following immunosuppression withdrawal

Previous work indicated that appropriate end-organ reinnervation fails to influence axonal degeneration in nerve allografts following immunosuppression withdrawal. In the present study, we examined if differences existed in axonal degeneration when axons regenerated across nerve allografts are allowed or completely denied end-organ reinnervation. Two ACI rat nerve allografts (3 cm long) were sutured into gaps created in both peroneal nerves in Lewis rats. In the right leg, the distal end of the graft was connected to the distal host nerve stump to allow end-organ reinnervation. In the left leg, the distal end was turned back and double ligated (unconnected) to prevent end-organ reinnervation. Rats received Cyclosporin A daily for 12 weeks to allow for regeneration and were sacrificed at 16 (n = 5) or 18 (n = 5) weeks following engraftment to assess axonal degeneration following immunosuppression withdrawal. Five Lewis rats receiving autografts served as control and were sacrificed at 12 weeks. Morphometric analysis was performed. In the control group (autografts) the cross-sectional area of and the number of myelinated fibres in the unconnected grafts was double that of the connected grafts, suggesting a sprouting effect. There was a tenfold reduction in the mean number of fibres at weeks 16 and 18 in the allografts compared to controls, without any significant differences in the connected versus unconnected sides. End-organ reinnervation decreases sprouting of axons within the graft but does not protect axons from degeneration following immunosuppression withdrawal.

Chitin synthesis in human pathogenic fungi

In recent years it has become evident that the structural polysaccharide chitin is synthesized from a family of enzymes encoded by multiple CHS chitin synthase genes, and regulated by an array of ancillary gene products that influence CHS activation and localization. Considerable attention has therefore been given to elucidating the function of specific CHS gene products in individual fungi. In those fungi in which individual CHS genes have been deleted systematically, there is little evidence for redundancy of function in family members. Chs enzymes are now known that participate in lateral wall biosynthesis, septum synthesis and spore formation but the phenotype of some CHS gene mutations is subtle, and so the role of the corresponding isoenzymes remains obscure. Nonetheless, it has become clear that certain members of the CHS gene families of fungi are more important for growth, integrity and viability than others, and this knowledge has already led to the design of new classes of antifungal agents that are targeted against key enzyme activities. Future work in this area will help define how individual Chs enzymes are targeted to specific regions of the cell wall and at specific times of the cell cycle, and should facilitate the rational development of novel and highly specific antifungal agents.

Beta-adrenergic blockade in the dentate gyrus in vivo prevents high frequency-induced long-term potentiation of EPSP slope, but not long-term potentiation of population spike amplitude

High frequency (HF)-induced and norepinephrine (NE)-induced long-term potentiation have been hypothesized to utilize common mechanisms of induction and expression in the dentate gyrus. In vitro data tend to support this hypothesis, but few studies have been done in vivo. The present study records perforant path-evoked potentials simultaneously on two micropipettes, one filled with saline and the other with the beta-antagonist, timolol. Stimulation of the paragigantocellularis nucleus (PGi) was used as a method of producing NE release in the dentate gyrus, and thus, to assess the efficacy of beta-receptor blockade on the timolol pipette. Beta-blockade by timolol attenuated PGi-induced spike potentiation. HF-induced potentiation of the excitatory post-synaptic potential (EPSP) slope was also blocked by timolol, but HF-induced spike amplitude potentiation was unaffected. These results are consistent with an earlier report examining HF-long-term potentiation (LTP) following 6-OHDA-induced NE depletion, which showed that the EPSP slope LTP depended, for its full expression, on NE, but potentiation of the population spike amplitude component of HF-induced LTP did not. In the present study, PGi-induced potentiation of spike amplitude on the saline pipette was normal after HF-induced saturation of spike amplitude potentiation, suggesting that the mechanisms for expression of spike potentiation, as well as induction of spike potentiation, are separate for HF and NE stimulation.

Alcohol dementia: "cortical" or "subcortical" dementia?

Most dementias are considered to exhibit either a predominantly "cortical" (e.g. Alzheimer's disease, AD) or "subcortical" (e.g. Parkinson's disease) pattern. A double dissociation has been reported, such that cortical and subcortical dementias can be differentiated based on performance on tests of declarative and procedural learning. The goal of this study was to determine if subjects with alcohol dementia exhibit a predominantly cortical or subcortical dementia profile. The performance of 10 elderly subjects diagnosed with alcohol dementia, 29 elderly subjects with histories of alcohol dependence but who were not demented, and 11 subjects with AD was compared to 20 elderly control subjects. The results indicated that the procedural learning task did not differentiate among the groups, whereas the discriminability index from the California Learning Test (the declarative learning task) did. Thus, alcohol dementia cannot clearly be ascribed to either dementia classification.

Prospective analysis of relationships of outcome measures for ulnar neuropathy at the elbow

BACKGROUND

We undertook a prospective study to investigate relationships between outcome measures of ulnar neuropathy at the elbow.

METHODS

Thirty-one patients (mean age 52.6, range 20-80), with clinically and electrically verified ulnar neuropathy at the elbow, were seen independently by a neurosurgeon and a physiotherapist. All tests were administered to all patients on each visit. Data collected included measures of sensory (monofilament, two-point discrimination, vibration) and motor function (grip, key-pinch, muscle atrophy), pain (visual analogue scale (VAS)) and impact on lifestyle (Levine's questionnaires (function status score--FSS, symptom severity score--SSS)), disability of the arm, shoulder and hand module (DASH) and patient-specific measures (PSM). Parametric and non-parametric correlation and factor analysis were done.

RESULTS

Outcome analysis was available for 63 patient visits, with follow-up obtained for 20 patients (mean 8.5 months). Lifestyle and pain instruments (FSS, SSS, DASH, PSM and VAS) all correlated well with each other (r > 0.6, p < .01). DASH was moderately to highly correlated to nine of the 11 measures. Some tests correlated poorly, for example, Semmes-Weinstein monofilament with other sensory measures and muscle atrophy with almost all measures. Factor analysis revealed that there are two principal factors, accounting for 77% of the variance. Factor 1 relates to impact on lifestyle and pain while Factor 2 relates to strength and function.

DISCUSSION/CONCLUSIONS

Intraclass measures, particularly ones assessing lifestyle and pain instruments are strongly correlated. Factor analysis revealed two principal factors that account for the majority of the variance; future studies with a larger sample size are needed to validate this analysis.

Alcohol, dementia, and Alzheimer's disease: comparison of neuropsychological profiles

Thirty-nine detoxified elderly alcoholics (mean age = 65.85) completed a comprehensive assessment designed to identify individuals meeting DSM-IV criteria for alcohol-related dementia. Ten subjects meeting criteria (mean age = 69.8; mean Mini-Mental State Examination [MMSE] = 25.1) were compared to the 29 nondemented alcoholics (mean age = 64.5; mean MMSE = 27.8), 9 patients with Alzheimer's disease (mean age = 73.4; mean MMSE = 22.3), and 15 control subjects (mean age = 70.8; mean MMSE = 28). Comparison of neuropsychological test scores revealed several statistically significant differences. Furthermore, the overall pattern of test performance between the two demented groups was different. Alzheimer's patients were more impaired on confrontation naming, recognition memory, animal fluency, and orientation. Alcohol dementia subjects were more impaired than controls on initial letter fluency, fine motor control, and free recall. However, alcohol dementia subjects did not differ from controls on tests of verbal recognition memory. This study suggests that it is possible to clinically differentiate the cognitive deficits of alcohol-related dementia from typical Alzheimer's disease. However, the results are preliminary and are based on small sample sizes so should be interpreted with caution.

Chs1 of Candida albicans is an essential chitin synthase required for synthesis of the septum and for cell integrity

CaCHS1 of the fungal pathogen Candida albicans encodes an essential chitin synthase that is required for septum formation, viability, cell shape and integrity. The CaCHS1 gene was inactivated by first disrupting one allele using the ura-blaster protocol, then placing the remaining allele under the control of the maltose-inducible, glucose-repressible MRP1 promoter. Under repressing conditions, yeast cell growth continued temporarily, but daughter buds failed to detach from parents, resulting in septumless chains of cells with constrictions defining contiguous compartments. After several generations, a proportion of the distal compartments lysed. The conditional Deltachs1 mutant also failed to form primary septa in hyphae; after several generations, growth stopped, and hyphae developed swollen balloon-like features or lysed at one of a number of sites including the hyphal apex and other locations that would not normally be associated with septum formation. CHS1 therefore synthesizes the septum of both yeast and hyphae and also maintains the integrity of the lateral cell wall. The conditional mutant was avirulent under repressing conditions in an experimental model of systemic infection. Because this gene is essential in vitro and in vivo and is not present in humans, it represents an attractive target for the development of antifungal compounds.

MR properties of rat sciatic nerve following trauma

T(1) and T(2) relaxation times, magnetization transfer (MT), and diffusion anisotropy of rat sciatic nerve were measured at different time intervals following trauma. The nerve injury was induced by either cutting (irreversible nerve degeneration) or crushing (degeneration followed by regeneration). The MR properties were measured for proximal and distal portions of the injured nerve. The portions of the nerve proximal to the induced injury exhibited MR characteristics similar to those of normal nerves, whereas the distal portions showed significant differences in all MR parameters. These differences diminished in the regenerating nerves within approximately 4 weeks post injury. In the case of irreversible nerve damage, the differences in the distal nerves were slightly larger and did not resolve even 6 weeks after induced trauma. The MR measurements were correlated with histopathology exams. Observed changes in tissue microstructure, such as demyelination, inflammation, and axonal loss, can result in a significant increase in the average T(1) and T(2) relaxation times, reduction in the MT effect, and decrease in diffusion anisotropy. MR parameters, therefore, are very good indicators of nerve damage and may be useful in monitoring therapies that assist nerve regeneration. Magn Reson Med 45:415-420, 2001.

Differential response of sensory and motor axons in nerve allografts after withdrawal of immunosuppressive therapy

OBJECT

Rejection of nerve allografts and loss of regenerated host axons after withdrawal of immunosuppressive therapy poses an ongoing challenge in peripheral nerve repair. The present report is of a blinded prospective controlled study in which an established rat model of nerve allotransplantation is used to examine the effect of fiber type on survival and degeneration of nerve allografts after discontinuation of immunosuppression. The authors hypothesized that sensory axons will selectively resist a rejection response, whereas motor axons will degenerate.

METHODS

Four-centimeter nerve segments from ACI rats were grafted into peroneal and sural (mixed) or saphenous (sensory) nerve gaps in Lewis rats. In some rats, L4-6 dorsal root ganglia were ablated before grafting, creating pure motor sural and peroneal nerves. All rats received 12 weeks of immunosuppressive therapy to support nerve regeneration into allografts. Immunosuppression with cyclosporin was then withdrawn. At planned death (12-18 weeks postsurgery), graft tissue was subjected to histomorphometric analysis for evaluation of axon survival and loss. Graft rejection led to loss of all axons in approximately 60% of the allograft segments. The mixed nerve group was most prone to complete rejection, with significantly lowered axon counts at Weeks 16 and 18 compared with the Week 12 baseline. Axons from the sensory nerve were least likely to degenerate. The pure motor nerve group axons demonstrated intermediate sensitivity, with a selective loss of larger axons at Week 16 and a significant decrease in axon counts from the Week 12 baseline at Week 18.

CONCLUSIONS

Whereas the majority of axons are lost after withdrawal of immunosuppressive therapy from nerve allografts, there is a selective survival of axons from cutaneous sensory nerves and smaller-diameter motor fibers. The biological and molecular mechanisms that make some axons impervious to injury remain to be determined.

Normative data on the Boston Naming Test and two equivalent 30-item short forms

Because of the significance of the Boston Naming Test (BNT) in the differential diagnosis of the dementias, especially Alzheimer's disease, adequate norms from community-dwelling elderly individuals are essential. The present study describes the development of two new empirically derived equivalent short forms (30 items each) of the test. Normative data for the total BNT and the two equivalent 30-item halves based on item difficulty are presented using the performance of 314 community-dwelling individuals aged 65 and over. Age and education norms are presented using an overlapping midpoint interval strategy.

The neuropsychological consequences of abstinence among older alcoholics: a cross-sectional study

BACKGROUND

The older alcoholic has been distinguished from the younger alcoholic with regard to both the acute effects of alcohol and also the recovery of functioning with abstinence. Few studies, however, have included samples of exclusively older subjects. In this investigation we examined the recovery of functioning in an older cohort of recovering alcoholics (age range 55-83) to determine which neuropsychological functions improve and which remain impaired with abstinence.

METHODS

We used a cross-sectional design, comparing three demographically matched groups on a battery of neuropsychological tests: (a) older alcoholics who had been abstinent for greater than 6 months, (b) older alcoholics who had been abstinent for less than 6 months, and (c) a control group of older subjects without alcohol abuse histories.

RESULTS

In almost all tasks, the alcoholics who were abstinent for less than 6 months performed worse than the control group. In contrast, the alcoholics who had been abstinent for more than 6 months differed from the control group on learning and recall of a word list, immediate and delayed recall of a complex figure, initial letter fluency, and clock drawing.

CONCLUSIONS

Memory and executive skills appear to be resistant to recovery or at least slower to recover with abstinence in the older alcoholic. The impairment with visuospatial skills reported in prior investigations of alcoholics may be related to compromised executive functions, which interfere with the encoding of more complex visuospatial information and thus affect recall of such information. Studies that involve larger samples of older alcoholics are needed to understand their ability to recover cognitive functioning with abstinence.

Detection of host and donor cells in sex-mismatched rat nerve allografts using RT-PCR for a Y chromosome (H-Y) marker

The donor and host source of support cells, such as Schwann cells, in nerve allograft segments have been the subject of debate. The objective of the present study was to assess the utility of a molecular technique that probes for a Y chromosome expressed gene (H-Y) in distinguishing host from donor tissue in sex-mismatched nerve allograft segments. Forty-two Lewis rats received bilateral syngeneic Lewis or allogeneic ACI rat peroneal nerve grafts, with or without cyclosporin A (CsA) treatment. At different times thereafter animals were sacrificed and samples were harvested. We transplanted males and females reciprocally, to study both survival of donor cells (persisting H-Y mRNA in male grafts by transcription polymerase chain reaction (RT-PCR), and graft infiltration by host cells (detectable H-Y mRNA in female grafts). A kinetic analysis revealed a progressive loss of viable donor cells (loss of H-Y mRNA signal) from allografts, beginning 2-3 weeks, and culminating at 4 weeks, with little detectable H-Y in the absence of CsA treatment. CsA treatment led to prolonged survival of allograft cells, confirmed by detectable H-Y mRNA. By studying female grafts in male rats we could confirm that loss of viable donor tissue in allografts was accompanied by infiltration of host (H-Y mRNA positive) cells, whereas no H-Y mRNA signal was seen in males receiving autografts from females or in immunosuppressed allograft segments. These data suggest that reverse RT-PCR analysis for a Y chromosome gene product can be a valuable tool to assess the origin of viable cells in sex-mismatched nerve allotransplantation tissue.

Long nerve allografts in sheep with Cyclosporin A immunosuppression

Rodent studies of nerve allografts are limited by a relatively short length of graft segment. The authors attempted to establish an outbred sheep model that would allow the study of longer, more clinically relevant nerve gaps. Using outbred ewes, two 8-cm long radial sensory nerves were grafted into gaps (5 cm) in the median nerve. Sheep received an autograft and an allograft. Four sheep were immunosuppressed with Cyclosporin A (CsA) and four were controls. Blood CsA levels greater than 1000 microg/L were obtained. Systemic immunosuppression resulted in severe opportunistic infections, and the sheep were sacrificed between 35 and 47 days following surgery. Histologically, in the autografts and CsA-treated allografts, evidence of nerve regeneration was seen. Non-immunosuppressed allografts were clearly rejected. While clear differences in the histology of experimental and control grafted nerve tissues were seen, the sheep allograft model presents considerable challenges due to immunosuppression-related infectious complications.

Differential expression of chitin synthase genes during temperature-induced dimorphic transitions in Paracoccidioides brasiliensis

Fragments of five genes encoding chitin synthase enzymes were identified in the dimorphic fungus Paracoccidioides brasiliensis by polymerase chain reaction (PCR) amplification of conserved CHS gene domains. These represent several classes of enzyme: PbrCHS1, class I; PbrCHS2, class II; PbrCHS3, class IV; and PbrCHS4 and PbrCHS5, class V. Expression of these genes during the temperature regulated dimorphic transition from yeast to mycelium and from mycelium to yeast was determined by Northern analysis. One gene (PbrCHS3) was not expressed at detectable levels. The others were regulated by morphology and/or by the growth phase of the organism. Despite the fact that yeast cells contain more chitin than hyphal cells, the levels of mRNA for PbrCHS1, PbrCHS2, PbrCHS4, and PbrCHS5 were higher in hyphal cells than in yeast cells. This supports observations in other fungi that transcript levels often do not correlate with chitin content and that post-transcriptional regulation of CHS gene expression is important for morphogenesis.

Lack of association between outcome measures of nerve regeneration

Studies of nerve regeneration in rodents utilize at least one of three classes of outcome measures: electrophysiology, morphometry, and functional tests. The assumption that these measures are correlated was tested utilizing a data set of 16 variables. Significant correlations (Spearman's rho, P < or = 0.05) were found within variable classes; however, none were found between classes. The three commonly utilized outcome measures do not measure the same phenomenon but rather discrete aspects of nerve regeneration.

Analysis of upper and lower extremity peripheral nerve injuries in a population of patients with multiple injuries

BACKGROUND

The purpose of this study was to determine the prevalence, cause, severity, and patterns of associated injuries of limb peripheral nerve injuries sustained by patients with multiple injuries seen at a regional Level 1 trauma center.

METHODS

Patients sustaining injuries to the radial, median, ulnar, sciatic, femoral, peroneal, or tibial nerves were identified using a prospectively collected computerized database, maintained by Sunnybrook Health Science Centre, and a detailed chart review was undertaken.

RESULTS

From a trauma population of 5,777 patients treated between January 1, 1986, and November 30, 1996, 162 patients were identified as having an injury to at least one of the peripheral nerves of interest, yielding a prevalence of 2.8%. These 162 patients sustained a total of 200 peripheral nerve injuries, 121 of which were in the upper extremity. The mean patient age was 34.6 years (SEM +/- 1.1 year), and 83% of patients were male. The mean injury severity score was 23.1 (+/-0.90), and the mean length of hospital stay was 28 days (+/-1.8).

CONCLUSIONS

Motor vehicles crashes predominated (46%) as the cause of injury. The most frequently injured nerve was the radial nerve (58 injuries), and in the lower limb, the peroneal nerve was most commonly injured (39 injuries). Diagnosis of a peripheral nerve injury was made within 4 days of admission to Sunnybrook Health Science Centre in 78% of the cases. Surgery was required to treat 54% of patients. Head injuries were the most common associated injury, occurring in 60% of patients. Other common associated injuries included fractures and dislocations. The present report aims to aid in identification and treatment of peripheral nerve injuries.

Regulation of chitin synthesis during dimorphic growth of Candida albicans

Candida albicans has three genes encoding chitin synthase enzymes. In wild-type strains, the expression of CHS2 and CHS3 peaked 1-2 h after the induction of hyphal growth, whilst mRNA levels in a non-germinative strain, CA2, remained low under the same conditions. CHS1 gene expression did not peak during germ tube formation but remained at low levels in both yeast and hyphal growth. The pattern of gene expression did not predict the changes in measured chitin synthase activities or changes in chitin content during dimorphic transition. Chitin synthase activity increased steadily, and did not peak shortly after germ tube induction, and activity profiles were similar in germ-tube-competent and germ-tube-negative strains. The phenotype of a delta chs2 null mutant suggested that CHS2 encoded the major enzyme activity in vitro and was largely responsible for elevated chitin synthase activities in microsomal preparations from hyphal cells compared to yeast cells. However, CaChs3p was responsible for synthesis of most chitin in both yeast and hyphae. Three independent chitin assays gave markedly different estimates of the relative chitin content of yeast and hyphae and wild-type and chs mutants. Only one of the methods gave a significantly higher chitin content for hyphal compared to yeast cell walls and a lower chitin content for hyphae of the delta chs2 null mutant compared to the parental strain.

Motor and sensory specificity of host nerve axons influence nerve allograft rejection

Previous studies have shown both survival and loss of regenerated host axons within nerve allograft segments after withdrawal of Cyclosporin A (CsA) immunosuppression. We hypothesized that the nature of end-organ reinnervation may influence the response of the axon, with survival of axons for appropriate innervation vs degeneration for inappropriate innervation. The rat femoral nerve model was chosen, as it has approximately equal sensory (S) and motor (M) divisions. Four ACI rat peroneal nerve allografts were sutured in straight (right leg: MM and SS) or switched (left leg; MS and SM) orientation in each femoral nerve transection gap in each Lewis rat recipient. Rats received CsA for 8 weeks to allow end-organ reinnervation, after which immunosuppression was discontinued. Rats were killed at various times thereafter, and underwent histologic and morphometric analysis of the graft segment axons. The regenerated axon population in the allograft reflected the nerve of origin: significantly more but smaller fibers when the proximal nerve was sensory and fewer but larger fibers when the proximal nerve was motor. After CsA withdrawal, there was a marked decrease of host axons as part of an ensuing rejection episode. The overall proportional decrease of axons was similar across all nerve orientation groups and, therefore, did not appear to be influenced by the nerve of origin or by the end-organ. However, the sensory proximal groups (SS and SM) contained more mature, noninjured fibers, while the motor proximal groups (MM and MS) contained significantly more degeneration and newly regenerating axons. We conclude that the motor or sensory nerve origin of the host axon, rather than the end-organ, influences axon survival after immunosuppression cessation. It is hypothesized that sensory axons may be more resilient while motor axons are selectively vulnerable to this second injury.

Application of curve regeneration to the determination of electrolytes by the Flame IV Auto-Analyser using a mini-computer

Curve regeneration is applied to the continuous-flow determination of serum Na +, K +, Cl- and CO2 by the Flame photometer IV (Technicon Corp.). A Hewlett-Packard 2100 A mini-computer is used for data acquisition. The continuous-flow parameters of both rise and fall curves are estimated from computer sampled voltage outputs over the standard profile. An additional interaction correction variable designated as Beta (beta) is described and applied to the regenerated peaks of the cresol red CO2 procedure. The phenolphthlalein CO2 methodology, showing improved flow parameters over those for the cresol red procedure is adapted for the Flame IV system. The basic program design is briefly outlined. Typical computer determined calibration curves (linear regression) and sample peak tracings for both the basic and regenerated techniques are illustrated.

Curve prediction in automated analyses in routine laboratories

1. The hydraulics of first- and second-generation AutoAnalyzers introduce lag and exponential deformations of the square wave signal expected from the colorimeter. These factors limit sampling rates by causing sample interaction. Curve regeneration carried out on Technicon Flame IV modules, using a digital approach, with a Hewlett-Packard 2100A computer, has successfully compensated for exponential deformation of sodium, potassium, chloride and carbon dioxide channels in routine laboratory use for one year. A sampling rate of 138/hr has been used; faster rates are possible. 2. Reduced sample and reagent consumption are benefits in addition to the increased analysis rate.