Meltwater temperature in streams draining Alpine glaciers.

Climate change is significantly impacting lotic environments, through changes to hydrology, biodiversity and species distribution. Effects of climate change are greatest at high elevation and biota in and around glacier-fed rivers is likely, therefore, to be at great risk. How climate change influences hydrology will have great impact on river water temperature as glacier-fed rivers in Alpine environments are extremely sensitive to climatic change. This paper assesses five rivers: Four glacier-fed rivers (36.9-83.7% basin glacierisation) located in the Swiss Alps, and one located in an ice-free catchment in the Bernese Oberland, Switzerland. The aim was to assess the impact of basin characteristics on river water temperature. A distinct paradoxical relationship was identified whereby water temperature in some glacier-fed rivers was reduced during the time of highest incoming shortwave radiation receipts and high air temperature. Whether a summer cooling effect presented itself in all glacier-fed rivers within this study was researched. The key findings were that the identified summer cooling effect was not present in all rivers, despite percentage glacierisation. Percentage glacier cover has often been reported as they key determiner of water temperature in such rivers. More important was the stream dimensions, notably stream surface area. Understanding the controlling factors that influence water temperature of glacier-fed rivers will help river managers and planners in understanding how climate change will affect fisheries downstream of glaciers over the coming decades. This may allow plans to be introduced to try and mitigate warmer water temperature that will result, in some glacier-fed rivers, as the climate warms.

Snowmelt contributions to discharge of the Ganges.

Himalayan headwaters supply large quantities of runoff derived from snowmelt and monsoon rainfall to the Ganges River. Actual snowmelt contribution to discharge in the Ganges remains conjectural under both present and future climatic conditions. As snowmelt is likely to be perturbed through climatic warming, four hydrological models, VIC, JULES, LPJmL and SWAT, appropriate for coupling with regional climate models, were used to provide a baseline estimate of snowmelt contribution to flow at seasonal and annual timescales. The models constrain estimates of snowmelt contributions to between 1% and 5% of overall basin runoff. Snowmelt is, however, significant in spring months, a period in which other sources of runoff are scarce.

A therapeutic HIV vaccine using coxsackie-HIV recombinants: a possible new strategy.

The ultimate goal in the treatment of HIV-infected persons is to prevent disease progression. A strategy to accomplish this goal is to use chemotherapy to reduce viral load followed by immunotherapy to stimulate HIV-specific immune responses that are observed in long-term asymptomatic individuals. An effective, live, recombinant virus, expressing HIV sequences, would be capable of inducing both CTL and CD4(+) helper T cell responses. To accomplish these goals, the viral vector must be immunogenic yet retain its avirulent phenotype in a T cell-deficient host. We have identified a coxsackievirus variant, CB4-P, that can induce protective immunity against a virulent variant. In addition, the CB4-P variant remains avirulent in mice lacking CD4(+) helper T cells, suggesting that CB4-P may be uniquely suited as a viral vector for a therapeutic HIV vaccine. Two strategies designed to elicit CTL and CD4(+) helper T cell responses were used to construct CB4-P/HIV recombinants. Recombinant viruses were viable, genetically stable, and retained the avirulent phenotype of the parental virus. In designing a viral vector for vaccine development, an issue that must be addressed is whether preexisting immunity to the vector would affect subsequent administration of the recombinant virus. Using a test recombinant, we showed that prior exposure to the parental CB4-P virus did not affect the ability of the recombinant to induce a CD4(+) T cell response against the foreign sequence. The results suggest that a "cocktail" of coxsackie/HIV recombinants may be useful as a therapeutic HIV vaccine.

Scraggly, a new hair loss mutation on mouse chromosome 19.

By use of chlorambucil, we have generated a mouse mutation called scraggly (sgl) that exhibits skin and hair defects. Homozygous mutant mice exhibit hair loss, skin defects, and abnormalities in sebaceous lipid composition. We have constructed a high-resolution genetic map of mouse Chromosome (Chr) 19 that links this mutation to the anonymous DNA marker D19Umi1. An additional cross, (BALB/c x CAST/Ei) F(1) x BALB/c, was used to map markers around this mutation as well as to map the potential candidate genes, Fgf8 and Cyp17. Allelism tests between sgl and asebia (ab), another hair loss mutation on mouse Chr 19, showed that these genes were separate and distinct.

T cells contribute to disease severity during coxsackievirus B4 infection.

By using a model of coxsackievirus B4-induced disease, the question of whether tissue damage is due to the virus or to immune-mediated mechanisms was addressed. Both viral replication and T-cell function were implicated in contributing to the severity of disease. Three stages (I to III) of disease, which correspond to periods of high viral titers, low viral titers, and no infectious virus, have been identified. Stage I disease is considered to be primarily the result of viral replication. Immunopathological mechanisms appear to contribute to the severity of stage II and III disease. To investigate the role of T cells in contributing to the severity of disease, viral infection in CD8 knockout (ko) mice and CD4 ko mice was analyzed. CD8 T-cell responses appear to be beneficial during early, viral disease but detrimental in later disease when viral titers are diminishing. CD4 ko mice, unlike the parental strain, survived infection. Viral replication was lower in the CD4 ko mice. Was survival due to decreased viral replication or to the lack of T-helper-cell function? To investigate further the role of T helper cells in contributing to tissue damage, viral infection in two additional ko strains (interleukin-4 [IL-4] ko and gamma interferon ko strains) was examined. A clear correlation between viral replication and the outcome of infection was not observed. The absence of IL-4, which may influence T-helper-cell subset development, was advantageous during early viral disease but deleterious in later disease. The results suggest that T-cell-mediated immunity is both beneficial and detrimental during coxsackievirus B4 infection.

Infection of the laboratory mouse with the intracellular pathogen Ehrlichia chaffeensis.

To determine the basis of susceptibility and resistance to human monocytic ehrlichiosis (HME), immunocompetent and immunocompromised mice were infected with Ehrlichia chaffeensis and bacterial loads were measured by PCR and by immunohistochemistry. Immunocompetent (C. B-17 and C57BL/6) mice cleared the bacteria within 10 days, but immunocompromised SCID and SCID/BEIGE mice developed persistent infection in the spleen, liver, peritoneal cavity, brain, lung, and bone marrow and became moribund within 24 days. Both immunocompromised strains lack T and B lymphocytes, but the SCID/BEIGE strain is also deficient in natural killer (NK) cell function. During advanced stages of disease, the infections were associated with wasting, splenomegaly, lymphadenopathy, liver granulomas and necroses, intravascular coagulation, and granulomatous inflammation. Histochemical and immunohistochemical localization studies confirmed the presence of bacteria in tissues, and viable bacteria were cultured from infected animals. The data reveal that T and/or B cells play an essential role during resistance of immunocompetent mice to infection with E. chaffeensis and demonstrate the utility of immunocompromised mice as an experimental model for the study of HME.

Identification of persistent infection in experimental syphilis by PCR.

The studies described herein were designed to evaluate the usefulness of the PCR in detecting persistent syphilitic infection. Three groups of animals were used: a nonimmune group infected with Treponema pallidum (NI/TP), a nonimmune group injected with heat-killed treponemes (NI/HKTP), and an immune and reinfected group (I/TP). All animals were inoculated with similar numbers of organisms distributed at 10 sites on the clipped back and in both testes. The persistence of the treponemes was examined by PCR and the rabbit infectivity test (RIT). The kinetic studies and statistical analysis of their results demonstrated that the rate of bacterial clearance from the NI/TP group was very low and incomplete at 4 months after infection. It was significantly different from those of both the NI/HKTP (P < 0.001) and I/TP (P < 0.05) groups. No statistically significant differences in treponemal elimination were found between the NI/HKTP and I/TP groups. PCR can detect the DNA of dead organisms, but the latter are eliminated by the host relatively quickly (15 to 30 days) as compared to elimination of live treponemes (>120 days). PCR results correlated well with RIT results. These data suggest that PCR-positive specimens obtained from an untreated patient(s) or collected weeks after treatment indicate persistent infection. They also show that the process of elimination of T. pallidum from primary sites of infection is prolonged and incomplete.

Differential recruitment of B and T cells in coxsackievirus B4-induced pancreatitis is influenced by a capsid protein.

Two genetically similar variants of coxsackievirus B4, CB4-P and CB4-V, cause distinct disease syndromes in mice. A multidisciplinary approach was used to examine the events occurring in situ. The CB4-P variant induced acute pancreatitis, followed by repair of the exocrine tissues, while the CB4-V variant induced chronic pancreatitis, characterized by extensive destruction of the exocrine tissues. Since CB4-V replicated more efficiently than CB4-P in vivo, the more extensive tissue injury associated with CB4-V infection could be explained as the result of a higher level of viral replication. However, the fact that CB4-V replicated more efficiently in a mouse strain that survives infection than in a strain that succumbs to infection suggests that immune-mediated mechanisms as well as viral cytolysis may contribute to pancreatic tissue injury. To address the role of the immune system in virus-induced pancreatitis, the cell types within the inflammatory infiltrate were analyzed by flow cytometry. B cells (34 to 75%) were the most abundant, followed by T cells (10 to 30%), natural killer cells (4 to 8%), and macrophages (0 to 6%). Recruitment (and perhaps proliferation) of B and T cells to the pancreatic tissues was influenced by viral strain. Differential recruitment of T and B cells may reflect altered antigenic sites between CB4-P and CB4-V. The viral sequence that affected T- and B-cell recruitment was identified as a threonine residue at position 129 of the VP1 capsid protein.

Arthroplasty for arthritis and rotator cuff deficiency.

Massive and irreparable loss of rotator cuff tendon integrity can be associated with the development of glenohumeral and acromiohumeral arthritis. Loss of glenohumeral instability provided by the rotator cuff may initiate and perpetuate this unique condition of the shoulder. Proximal humeral replacement arthroplasty is the preferred surgical treatment; special techniques of this procedure are presented. Patients are gratified by the durable restoration of comfort and, to a lesser extent, function.

Sample size calculations for rescreening cytologic smears.

OBJECTIVE: To describe a method of calculating sample size if rescreening of cytologic material becomes necessary for legal or other reasons. The number of specimens to be reexamined must be large enough to provide adequate confidence in the results and small enough to minimize the cost of investigation. CONCLUSION: Except under very unusual conditions, the sample size is larger than generally thought.

A point mutation in the VP4 coding sequence of coxsackievirus B4 influences virulence.

In analyzing the molecular determinants of virulence of coxsackievirus B4, chimeric viruses were constructed from avirulent and virulent viruses. The vCB424 recombinant contained a single nucleotide substitution on an avirulent genetic background, resulting in replacement of Ser-16 of VP4 with Arg-16. Mice infected with vCB424 displayed an intermediate phenotype.

Metal transport in a stream polluted by acid mine drainage--The Afon Goch, Anglesey, UK.

Sampling of the Afon Goch over a 14-month period revealed maximum dissolved Fe, Al, Mn, Cu and Zn concentrations of 259, 167, 49, 60 and 42 mg dm(-3), respectively, and pH as low as 2.3, making it one of the most metal- and acid-contaminated streams in the UK. The river produces particulates by precipitation of ferrihydrite, due to the entry of near-neutral tributary waters, under all discharge conditions. Consequently, metal transport in this stream is dominated by processes different from those in less contaminated streams. The stream acts as a sink for contaminants, except under high discharge, when accumulated metals are flushed from the system. The implications of these observations for the monitoring and management of streams polluted by acid mine drainage are discussed.

Developments in three-dimensional stereo brightfield microscopy.

We present recent developments of a widefield computer/microscope system and image reconstruction algorithm for producing three-dimensional (3D) increased depth of field images in the form of brightfield stereo pairs of thick specimens. The theoretical principle of this image reconstruction technique is based on Weiner-type inverse filtering. A number of extensions and refinements to our previous work have included further testing of the system with a broader class of specimens and the implementation of several pragmatic refinements important for future 3D microscopy systems. These refinements include histogram modification routines for improving visualization, a preprocessing routine to eliminate edge artifacts due to circular convolution and other effects, stereo viewing angle optimization, a rule of thumb estimate for the axial sampling rate, and incorporation of a variation of the Fast Fourier Transform and filtering operations that significantly reduce computational time. Images of spyrogyra, neonatal rat hippocampal neurons, and cervical/vaginal cell smears are presented to show the utility of these methods for 3D visualization. The primary advantages of these methods are that they operate with an ordinary transmitted light microscope and are inexpensively implemented on a personal computer with reasonable computation time.

Vena caval filter use in orthopaedic trauma patients with recognized preoperative venous thromboembolic disease.

This study comprises a series of 35 patients with pelvic or lower extremity fractures requiring surgery who also had a documented significant acute deep venous thrombosis (DVT). The authors treated these with low-dose Coumadin and 36 vena caval filters, which were used prophylactically prior to surgery. The patients received low-dose warfarin after placement of the vena caval filters and were maintained at 1.3-1.5 times the prothrombin control value for 6 weeks to 3 months. In this group of patients, there were no fatal pulmonary emboli and no clinically significant complications from filter placement. There were nine asymptomatic filter complications demonstrated radiographically in eight patients. Additionally, one patient with a tilted vena caval filter required placement of another filter. The combination of vena caval filters and low-dose warfarin appears to be a successful and relatively safe method of managing those patients who have acute DVT and require surgery for their pelvic or lower extremity fractures.

Cervical spine instability in rheumatoid patients having total hip or knee arthroplasty.

The records and roentgenographs of 113 rheumatoid patients treated by total hip or knee arthroplasty were analyzed retrospectively. The cervical spine roentgenographs were evaluated for significant atlantoaxial subluxation, atlantoaxial impaction, and subaxial subluxation. One or more of these findings were present in 69 (61%) of the patients. Thirty-five of the 69 (50%) with roentgenographically documented cervical spine instability had no signs or symptoms of instability at the time of admission for joint replacement. This high incidence of cervical spine instability in a select population of rheumatoid patients emphasizes the importance of preoperative evaluation of the cervical spine including flexion and extension lateral roentgenographs.

Postoperative urinary retention associated with total hip and total knee arthroplasties.

Urinary retention following total hip and knee arthroplasty is a common problem frequently necessitating either prolonged urethral catheter drainage or intermittent catheterization. The direct relationship of urinary tract instrumentations, procedures, and infections to deep sepsis in total hip replacements is well documented. Pharmacologic therapy to stimulate voiding or augment bladder emptying is thus theoretically preferable to the use of catheterization. Prasozin hydrochloride, an alpha blocker, relaxes the smooth musculature of the posterior urethra and prostrate and has been used to treat urinary obstruction secondary to benign prostatic hypertrophy. A prospective study in 60 male patients showed a statistically significant decrease in postoperative urinary retention with the perioperative administration of prazosin (p less than 0.01). A higher incidence of urinary tract infection was seen in patients who developed urinary retention (3% versus 20%) (p less than 0.01). Uroflowmetry parameters were not predictive of the patient at risk for retention and were unaltered with the administration of prazosin. Prazosin can be an effective adjunct in the prophylaxis of postoperative urinary tract infections and may decrease the potential risk for total joint sepsis.

Noncemented porous-coated anatomic total hip arthroplasty.

In 1984, as an alternate to the acrylic fixation of the components of total hip arthroplasty, the use of an uncemented porous-coated anatomic (PCA) hip system with a beaded porous coating to achieve biologic fixation was initiated. Since then, 44 patients with cementless acetabular components and 35 patients with cementless femoral components have been followed for a minimum of 24 months and an average of 37 months. Harris hip scores averaged 90.5 at most recent follow-up intervals. No reoperations were necessary for failures of fixation or change in position of the acetabular component. Ominous roentgenographic signs such as progressive bead shedding, progressive radiolucencies, or progressive component migration have not occurred. Two femoral component revisions have been necessary: one for intractable pain and one for pain and roentgenographic loosening. Although thigh pain has been prevalent (20%), all patients have been accommodated and have retained stable hip scores. Progressive radiolucencies and progressive implant subsidence have been rare occurrences. The authors continue to use the cementless acetabular component in all cases of total hip arthroplasty in which initial stability can be obtained. It is their preference to cement the femoral component in patients over 65 or when initial stability cannot be achieved.

Infections at the site of a hip implant. Successful and unsuccessful management.

Thirty-four patients developed the complication of deep infection at the site of a hip implant (n = 35). Multiple factors in existence at the time of implant placement and the time of presentation with infection as well as the therapeutic regimen were retrospectively analyzed. Patients with successful outcomes (n = 15) were relatively younger (mean, 52 years) compared to those that had an unsuccessful outcome (n = 19; mean, 65 years; p less than 0.01). No other factors were predictive of the outcome of treatment. Implant extirpation, expedient wound closure, and, when necessary, muscle transposition favored a successful outcome. Implant retention and open wound packing resulted in prolonged wound healing and, sometimes, hip disarticulation or death.