Resolution of recurrent hepatitis B in two liver transplant recipients treated with famciclovir

Recurrent hepatitis B infection after orthotopic liver transplantation remains problematic despite prophylaxis with hepatitis B immune globulin (anti-HBs IgG). Recently, famciclovir (an oral nucleoside analog) has been shown to have potent antiviral activity against hepatitis B in vitro as well as in patients with chronic hepatitis B. We present two patients who developed recurrent hepatitis B after orthotopic liver transplantation and were treated with famciclovir, 500 mg t.i.d. Both patients subsequently responded with marked improvement in biochemical liver tests and histology, with subsequent loss of hepatitis B surface antigen. Famciclovir is a useful agent in the treatment of hepatitis B in the liver transplant recipient.

A carrot leucine-rich-repeat protein that inhibits ice recrystallization

Many organisms adapted to live at subzero temperatures express antifreeze proteins that improve their tolerance to freezing. Although structurally diverse, all antifreeze proteins interact with ice surfaces, depress the freezing temperature of aqueous solutions, and inhibit ice crystal growth. A protein purified from carrot shares these functional features with antifreeze proteins of fish. Expression of the carrot complementary DNA in tobacco resulted in the accumulation of antifreeze activity in the apoplast of plants grown at greenhouse temperatures. The sequence of carrot antifreeze protein is similar to that of polygalacturonase inhibitor proteins and contains leucine-rich repeats.

Prophylaxis against hepatitis B recurrence following liver transplantation using combination lamivudine and hepatitis B immune globulin

Patients undergoing liver transplantation for hepatitis B-related liver disease are prone to recurrence. The mainstay of prophylaxis has been passive immunotherapy with hepatitis B immune globulin (HBIG). Antiviral therapy with lamivudine has proven effective in lowering hepatitis B virus (HBV) DNA and improving histology in patients with hepatitis B infection; its role in prophylaxis against hepatitis B recurrence following liver transplantation is under investigation. Viral breakthrough and resistance, however, are a significant problem with monotherapy with either HBIG or lamivudine. The efficacy of combination lamivudine/HBIG prophylaxis has not been reported. Fourteen patients underwent transplantation for decompensated liver disease owing to hepatitis B. Lamivudine (150 mg p.o./d) was begun before transplantation in 10 patients, including 4 who were HBV DNA-positive. In addition, 1 patient was HBV DNA-positive when transplanted. HBIG was given perioperatively and continued thereafter; treatment with lamivudine was maintained or initiated at the time of transplantation and continued indefinitely. The median follow-up was 387 days. Actuarial 1-year patient and graft survival was 93% (1 patient died of unrelated causes). At a median interval of 28 days following lamivudine treatment, all 5 HBV DNA-positive patients cleared HBV DNA from the serum; 1 went on to clear hepatitis B surface antigen (HBsAg), before transplantation, at day 148 of lamivudine treatment. By the highly sensitive polymerase chain reaction (PCR), at a median of 346 days (range, 130-525 days) following transplantation, all 13 surviving patients had no detectable serum HBV DNA. Lamivudine suppresses HBV replication in patients awaiting liver transplantation. At a median follow-up of 1.1 years, combination prophylaxis with lamivudine and HBIG prevented hepatitis B recurrence following liver transplantation.

Comparative motility of X and Y chromosome-bearing bovine sperm separated on the basis of DNA content by flow sorting

A combination of flow cytometric sperm sorting of X and Y chromosome-bearing sperm (X and Y sperm) and computer-assisted sperm analysis (CASA) for measuring sperm motility allows assessment of motion parameters in the two populations. Bull sperm were separated into X and Y populations by flow cytometry following staining with the DNA-binding dye Hoechst 33,342. The motion parameters differed depending on sperm concentration. Decreasing sperm concentration resulted in higher velocities and straighter trajectories. The concentrations of control (stained-unsorted and unstained-unsorted) and flow-sorted sperm were therefore adjusted to similar numbers (5 x 10(6) sperm per milliliter). Samples of sorted X and Y sperm and control sperm were transferred to prewarmed slides on a heated stage (37 degrees C) and their motion video recorded for 2 min using a magnification of x 100 and a high-resolution camera. The sperm analysis was carried out on a Hobson Sperm Tracker (HST) using HST 7 software. The following motion parameters were measured: curvilinear, straight-line, and average path velocity; mean angular displacement (MAD); beat cross-frequency; amplitude of lateral head displacement; linearity (LIN); and straightness of path (STR). Sperm movement was unaffected by staining with Hoechst 33,342, excitation by ultraviolet (UV) light, or the physical process of cell sorting. Significant differences were seen between X and Y sperm for MAD, LIN, and STR. No difference was observed for the other parameters. The results indicate that in a simple salts solution, Y bull sperm do not swim faster than X sperm but may be distinguished from X sperm on the basis of LIN and STR.

Discrimination among Bacillus cereus, B. mycoides and B. thuringiensis and some other species of the genus Bacillus by Fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy (FTIR) in conjunction with canonical variate analysis was found to be effective in discriminating among spectra of 9 representative strains of Bacillus spp., including B. cereus, B. mycoides and B. thuringiensis. The method was also able to discriminate according to species among spectra of 14 other non-type strains of B. cereus, 12 of B. mycoides and 12 of B. thuringiensis with a success rate of > 95%, even without using a prior classification of the groups by species. FTIR spectroscopy can be used for the rapid and accurate differentiation of species in the genus Bacillus that are of importance to the food and dairy industry.

A core-shell model of calcium phosphate nanoclusters stabilized by beta-casein phosphopeptides, derived from sedimentation equilibrium and small-angle X-ray and neutron-scattering measurements

Calcium phosphate nanoclusters were prepared under standardised conditions using 10 mg ml(-1) of the 25-amino-acid N-terminal tryptic phosphopeptide of bovine beta-casein as a stabilising agent. The Mr determined by sedimentation equilibrium was 197,600+/-13,700 and the apparent radius of gyration determined by X-ray scattering was 2.80+/-0.05 nm. A small-angle neutron scattering contrast variation study in 1H2O/2H2O mixtures was performed and gave radii of gyration at the calculated match points for the calcium phosphate (88.2% 2H2O) and phosphopeptide (41.3% 2H2O) of 3.39+/-0.08 nm and 1.85+/-0.05 nm, respectively. Measurements at larger scattering wave vector showed a subsidiary maximum at about Q = 1.6 nm(-1). The results are consistent with a model of the nanoclusters comprising a spherical core of 355+/-20 CaHPO4 x 2 H2O units, density 2.31 g ml(-1) and radius 2.30+/-0.05 nm surrounded by 49+/-4 peptide chains with a partial specific volume of 0.7 cm3 g(-1), forming a tightly packed shell with an outer radius of 4.04+/-0.15 nm. This model suggests that the phosphopeptide is able to arrest the process of growth of the precipitating phase of calcium phosphate at its earliest stages. A similar role for whole casein could be vital to the normal functioning of the mammary gland during milk secretion.

Genotyping of forensic short tandem repeat (STR) systems based on sizing precision in a capillary electrophoresis instrument

Automated fluorescence analysis of polymerase chain reaction (PCR)-amplified short tandem repeat (STR) systems by capillary electrophoresis (CE) is becoming an established tool both in forensic casework and in the implementation of both state and national convicted offender DNA databases. A new capillary electrophoresis instrument, the ABI Prism 310 Genetic Analyzer, along with the Performance Optimized Polymer 4 (POP-4) provides an automated and precise method for simultaneously analyzing ten fluorescently labeled STR loci from a single PCR amplification kit, which provides a power of discrimination of approximately one in five billion from a single PCR amplification. Data are presented on sizing precision, sizing accuracy, and resolution for the STR loci in the AmpFlSTR Profiler kit. Sizing accuracy is highly dependent on the electrophoresis system, and therefore the reporting of alleles based on the nucleotide size obtained from an electrophoresis system is not recommended for forensic work. The precision of the 310 capillary electrophoresis system, coupled with software developed for automated genotyping of alleles based on the use of an allelic ladder, allows for accurate genotyping of STR loci. Sizing precision of < or = 0.16 nucleotide standard deviation was obtained with this system, thus allowing for accurate genotyping of length variants that differ in length by a single nucleotide.

Cortisol, parathyroid hormone-related protein and the onset of calcium secretion by the mammary gland of the goat

During lactogenesis in the goat, the onset of secretion of calcium into milk occurs at parturition (Thompson et al. 1995) at approximately the same time as the onset of secretion of parathyroid hormone-related protein (PTHrP) by the mammary gland (Ratcliffe et al. 1992); these events may be unrelated or PTHrP may be involved in calcium transport from blood to milk.

Parturition in goats is initiated by fetal secretion of cortisol (Flint et al. 1978) and maternal secretion of cortisol also increases (Paterson & Linzell, 1971). Injecting cortisol locally into the sinus of a mammary gland of the late-pregnant goat when the tight junctions between secretory epithelial cells appear to be ‘loose’, and injectate can reach the basolateral surfaces of secretory cells, stimulates an early tightening of these junctions (Thompson, 1996) as occurs naturally at parturition. This tightening can be produced by an increased concentration of ionized calcium in the extracellular fluid of the gland (Neville & Peaker, 1981).

The experiments reported here were undertaken to determine if cortisol injection stimulates the mammary gland to secrete both PTHrP and calcium before parturition.

Use of OKT3 is associated with early and severe recurrence of hepatitis C after liver transplantation

OBJECTIVE

To determine whether increased immunosuppression is a contributor to poor outcome in hepatitis C-infected orthotopic liver transplant (OLT) recipients, we retrospectively analyzed the consequences of using OKT3 in our program for steroid-resistant rejection (SRR).

METHODS

We compared the histological recurrence of HCV in two contemporary cohorts of OLT recipients. Group 1 consisted of HCV-positive patients who received OKT3 for SRR (n = 19). Group 2 (n = 33) consisted of age-, gender-, and initial immunosuppression-matched HCV-positive controls who were treated with at least one steroid pulse for acute cellular rejection but who did not require treatment with OKT3. Liver biopsies were obtained per protocol within the first month and as necessary to evaluate abnormalities in serum liver chemistries.

RESULTS

Mean and median follow-up were comparable for the two groups. Recurrence of HCV was diagnosed by histological verification and was documented in 16 of 19 (84.2%) group 1 patients versus 17 of 33 (51.5%) group 2 patients (p = 0.03). The interval to recurrence was significantly shorter in patients who received OKT3 (p = 0.028). Logistic regression identified OKT3 as a significant risk factor for the recurrence of HCV within the first year post-OLT (p = 0.0004). The histological severity score, based on the most recent liver biopsy at long-term follow-up or the explant biopsy if the patient required retransplantation, was significantly higher in group 1. Moreover, cirrhosis was demonstrable in a greater proportion of allografts in patients who had received OKT3 at some point (26.3% vs. 6%, p = 0.028). Long-term follow-up revealed a trend toward higher alanine aminotransferase levels (p = 0.05) and total bilirubin (p = 0.08) in group 1 patients.

CONCLUSIONS

Our data suggest that allograft hepatitis in patients with preexisting HCV occurs earlier and with greater severity in patients treated with OKT3 for SRR, compared with age-, gender-, and initial immunosuppression-matched contemporary controls. Treatment of SRR with OKT3 may jeopardize long-term allograft function and survival in HCV-infected recipients by enhancing viral hepatitis recurrence. Clearly, the recognition of recurrent HCV and differentiation from acute cellular rejection remains a crucial issue in managing the OLT recipient with HCV.

Effect of temperature on the secondary structure of beta-lactoglobulin at pH 6.7, as determined by CD and IR spectroscopy: a test of the molten globule hypothesis

Previous CD measurements of changes in the conformation of beta-lactoglobulin at neutral pH as a function of temperature indicated the formation of a molten globule state above approx. 70 degrees C. New CD measurements are reported at temperatures up to 80 degrees C with an instrument on the Daresbury synchrotron radiation source which gives spectra of good signal-to-noise ratio down to 170 nm. IR spectra were recorded up to 94.8 degrees C with a ZnSe circle cell and a single simplified model of the substructure of the amide I' band was used to give the fractional contents of beta-sheet structure unambiguously and independently of the CD spectroscopy. The results of both techniques, however, were in agreement in showing a progressive loss of beta-sheet structure with increasing temperature, beginning below the denaturation temperature. Nevertheless, the CD spectroscopy showed a fairly abrupt loss of virtually all the helical conformation at approx. 65 degrees C. Comparison of the present results with other studies on the molten globule formed at acid pH in the lipocalin family suggests that above 65 degrees C a partly unfolded state is formed, possibly by destabilization of the intermolecular beta-strand I and the loss of the main helix, but it is not a classical molten globule transition.

Objectively measured boar sperm motility parameters correlate with the outcomes of on-farm inseminations: results of two fertility trials

Two fertility trials were undertaken to evaluate the relationship between boar semen quality and fertility (conception rate and litter size) after on-farm artificial insemination (AI). Trial 1 included 98 ejaculates from 27 boars, and trial 2 included 72 ejaculates from 26 boars. The semen quality was measured by computer-assisted semen analysis (CASA) using the Hobson Sperm Tracker. Boar semen was diluted in a standard extender (Beltsville Thawing Solution, BTS), dispensed into 75 ml allquots each containing 1.5 x 10(9) spermatozoa and dispatched to farms by overnight mail for use by their normal AI procedures. Randomly selected 75 ml aliquots of semen from each boar were also sent to the institute of Zoology for CASA measurement. Prior to CASA analysis, the spermatozoa were recovered from the BTS using Percoll gradients, resuspended in trisbuffered saline media containing 40 mM Ca++, and incubated at 39 degrees C. Parameters of sperm motion were measured after 0, 2, 4, and 6 hours of incubation. Various multiple regression models based on measured motion parameters could account for up to 24% of the variation in litter size. Using logistic regression, highly significant (P < 0.0001) models explaining conception rate in terms of sperm motion were derived for trial 2 only. The change in sperm velocity during the first 2 hours of incubation and the magnitude of the velocity parameters after 2 hours were identified as the most consistent indicators of fertility. Other attributes of sperm quality, i.e., frequency of spontaneous acrosome reactions (AR) and ARs induced by ionophore A23187 or solubilized pig zona pellucida, were also examined. When the "within-trial" median litter size was used as a way of allocating ejaculates to "high" or "low" litter-size groups, higher litter size was associated with lower frequency of both spontaneous and induced AR. These results demonstrate that fertility information can be derived from the CASA analysis of boar semen provided it is combined with a period of incubation in capacitating conditions.

Effect of sampling procedure and strain variation in Listeria monocytogenes on the discrimination of species in the genus Listeria by Fourier transform infrared spectroscopy and canonical variates analysis

The ability to discriminate successfully among cultures of all species of the Listeria genus by infrared spectroscopy in combination with canonical variate analysis was confirmed. The robustness of the method was demonstrated by showing that the separation of L. monocytogenes and L. grayi was hardly affected by variations in broth medium, incubation temperature, incubation time and cell washing procedure. Discrimination among 24 strains of L. monocytogenes according to serotype allowed two groups to be recognised, one comprising serotypes 4 and 4b and the other containing serotypes 1, 1/2b and 1/2c. When strain variation was included in the species discrimination model, the classification of all the L. monocytogenes strains was virtually 100% correct.

Graft loss following liver transplantation in patients with chronic hepatitis C

Liver disease due to hepatitis C (HCV) is an increasingly frequent indication for orthotopic liver transplantation (OLT). The aim of the current study was to analyze the causes of graft loss following OLT for chronic hepatitis C and the longterm outcome following retransplantation in a large university program. Between January 1990 and December 1995, 1183 patients underwent primary OLT at our center. In 304 patients, HCV was diagnosed by seropositivity and/or polymerase chain reaction. Fifty-six (18.4%) of these patients underwent retransplantation. The 36 patients retransplanted for primary non-function were excluded from further analysis. The other indications for regrafting (>30 days following primary transplant) included hepatic artery thrombosis (5), chronic rejection (4), severe HCV recurrence (5), and other etiologies (6). The cumulative survival rates for the 248 patients who received 1 OLT (group 1) were 84% after one year and 75% after three years. The corresponding rates for the 20 non-PNF patients who were retransplanted (group 2) were 60% and 43%, respectively (P<.0001). Moreover, logistic regression analysis confirmed that patients in group 2 were more than 4 times likely to die than patients in group 1 (P<.0034; risk ratio, 4.2; 95% confidence interval 1.61 to 11.37). Patients undergoing retransplantation had a high incidence of serious infectious complications leading to mortality. Two additional patients with severe recurrent HCV died awaiting liver retransplantation. Eight of the 304 total patients (2.6%) transplanted for chronic HCV developed graft failure secondary to HCV recurrence and 6 of the 8 were retransplanted; 3 of the 6 patients retransplanted are alive without evidence of histologic recurrence (mean follow-up less than 1 year). In summary, despite the high frequency of recurrent histologic evidence of HCV following primary OLT (70% at 3 years), graft loss attributable solely to HCV is an infrequent finding. Retransplantation per se is a risk factor for a fatal outcome, and the indication for reOLT does not appear to impact ultimate outcome. Serious infectious complications were the leading cause of mortality in patients retransplanted. Furthermore, given the indolent natural history of HCV, longer follow-up is necessary to determine the ultimate rate of graft loss due to HCV recurrence.

Choice of operating conditions to minimize sperm subpopulation sampling bias in the assessment of boar semen by computer-assisted semen analysis

The performance of a computer-assisted semen analysis system was evaluated for use with washed boar spermatozoa. Accuracy was tested using a computer graphics-generated series of spots moving along horizontal, vertical, and diagonal paths, with both straight and sinusoidal trajectories. Observed and expected values agreed to better than +/- 5%, and there was exact agreement in many cases. Reproducibility was tested by making 10 measurements of a single prerecorded sequence of boar spermatozoa. Coefficients of variation were < 3% for all sperm motion parameters tested. Setup conditions affecting the sample statistics of sperm populations were examined. Search radius (10 settings) and minimum track point (10 settings) were varied factorially to evaluate their biasing effects upon population sampling and accuracy. Low search radius (< 12 microns) or high minimum track point values (> 26 frames) precluded measurements of rapidly moving cells and thus led to selection of slow-moving cells. High search radius (> 16 microns) and low minimum track point settings (< 22 frames) led to erroneous tracking and poor data quality. Suitable settings for these setup parameters (search radius = 13 microns; minimum track points = 24) were chosen for use in subsequent fertility trials because they caused the least sampling bias.

Failure of ganciclovir prophylaxis to prevent allograft reinfection following orthotopic liver transplantation for chronic hepatitis B infection

The effect of ganciclovir prophylaxis on reinfection of hepatic allografts by hepatitis B virus (HBV) was studied in 26 patients undergoing orthotopic liver transplantation (OLT) for decompensated cirrhosis due to HBV. Patients were randomized to receive either ganciclovir (6 mg/kg/day intravenously for a total of 100 days) or acyclovir (10 mg/kg every 8 hours intravenously until discharged and then 800 mg orally every 6 hours) for a total of 100 days after OLT as part of a study of prophylaxis against cytomegalovirus infection. All patients received hepatitis B immunoglobulin (HBIG), 10,000 units intravenously, during the anhepatic phase, daily for the first 7 days, after OLT, and then every 4 weeks for 6 months, Seven of 12 (58%) patients in the ganciclovir group developed recurrent HBV, compared with 6/14 (46%) of the acyclovir group (nonsignificant). No significant difference was observed in time to recurrent HBV in the ganciclovir group (mean 13.2 months) compared to the acyclovir group (mean 11 months). Our results suggest that ganciclovir administered prophylactically for 100 days after OLT does not prevent or delay graft reinfection by HBV.

Major psychological disorders in acute and chronic TMD: an initial examination

This study assessed psychological disorders in 50 patients with chronic temporomandibular disorders and 51 patients with acute TMD. The results revealed a significant psychological comorbidity in both groups of patients. Both groups had high rates of psychopathology that exceeded the base rates of the general population. Such findings are in keeping with an integrated biopsychosocial model of TMD, and have significant implications for treatment of these patients.

Inhibition of protein tyrosine kinases impairs axon extension in the embryonic optic tract

The role of protein tyrosine kinase (PTK) activity in the development of the retinal projection was examined in vivo by applying inhibitors of cytoplasmic PTKs, herbimycin A and lavendustin A, to intact brain preparations of Xenopus embryos. The inhibitors were present during the period when retinal ganglion cell axons first navigate through the optic tract to reach their target, the optic tectum. A majority of inhibitor-treated retinal axons stalled at the beginning of the optic tract, leading to an 80% reduction in projection length at the highest doses. All inhibitor-treated axons that did extend into the optic tract exhibited normal pathfinding behavior. Tyrosine kinase assays of inhibitor-treated brains demonstrated that at doses at which retinal axon extension was severely impaired, PTK activity, including that of src family proteins, was reduced by 50-60%. Consistent with the in vivo findings, PTK inhibitors reduced neurite outgrowth from cultured retinal neurons by 70-80%. This contrasts with the strong enhancement of outgrowth induced by the same inhibitors in cultured chick ciliary ganglion neurons and suggests that the mediation of outgrowth by PTK activity may vary in different neuronal types. Inhibitor-treated growth cones cultured on laminin were larger than normal, suggesting that tyrosine phosphorylation can modulate growth cone-substrate adhesive interactions. Our results in vivo and in vitro provide complementary evidence that retinal axon outgrowth is inhibited by pharmacological blockers of PTK activity and indicate that inhibitor-sensitive PTKs normally play a role in promoting retinal neurite extension.

Ability of a beta-casein phosphopeptide to modulate the precipitation of calcium phosphate by forming amorphous dicalcium phosphate nanoclusters

The ability of casein in the form of colloidal-sized casein micelles to modulate the phase separation of calcium phosphate during milk secretion is adapted to produce nanometre-sized particles of calcium phosphate stabilized by a casein phosphopeptide (nanoclusters). The nanoclusters were prepared from an undersaturated solution of salts and the peptide by raising the pH homogeneously from about 5.5 to 6.7 with urea plus urease. Chemical analysis and IR spectroscopy showed that they comprise an amorphous dicalcium phosophate bound to the phosphopeptide. Multinuclear NMR spectroscopy of the cluster solutions showed that the small ions and free peptide in the solution were in a state of dynamic exchange with the nanoclusters. The peptide is linked to the calcium phosphate through its sequence of phosphorylated residues, but, in a proportion of adsorbed conformational states, the termini retain the conformational freedom of the unbound peptide. The ability of casein to form nanoclusters in milk suggests a more general mechanism for avoiding pathological calcification and regulating calcium flow in tissues and biological fluids exposed to or containing high concentrations of calcium.

Home Range Responses of Feral Goats

The variability in size and the extent of the overlap of feral goat home ranges are important considerations when formulating control strategies. Radio telemetry data revealed home range sizes were similar to what was found in other studies performed in pastoral areas. This study confirms the need for a wide ranging cooperative approach, by neighbouring pastoral properties, to feral goat control if all the feral goats using an area are to be targeted. Aerial control activities had little effect on the home ranges of resident feral goats and so can continue to be an effective control tool without causing the reinfestation of previously cleared areas.

Hepatotoxicity of anesthetics and other central nervous system drugs

A large number of anesthetics, tranquilizers, hypnotic sedatives, and anticonvulsants are used clinically. Although these agents are generally well tolerated, liver injury of differing patterns is well recognized with their use. Knowledge of the likelihood of hepatotoxicity and the characteristic clinical features with these compounds is important as fatal outcomes due to liver failure have been reported with several of these agents. This article describes the potential mechanisms and clinical features of drug hepatotoxicity associated with these compounds.

Thermal denaturation of beta-lactoglobulin: effect of protein concentration at pH 6.75 and 8.05

Previous work on the thermal denaturation of beta-lactoglobulin at about neutral pH and concentrations generally above 50 mg/ml has shown that the temperature of the maximum in the thermogram increases only slightly with concentration. Likewise, there is little if any concentration dependence at acid pH over a wide concentration range. However, so far as we are aware, no work has been described on the thermal denaturation of beta-lactoglobulin in the physiological range of protein concentration and pH appropriate to milk. We report measurements at pH 6.75 and 8.05 in the concentration range 2-120 mg/ml and show that below about 50 mg/ml the position of the maximum becomes strongly dependent on concentration, passing through a minimum near 25 mg/ml and increasing towards the lowest concentrations where measurements were practicable. Moreover, the narrow, well defined and nearly symmetrical thermal transition observed at high protein concentrations contrasts with a broader and more asymmetric curve at lower concentrations. An explanation for the behaviour seen at the lower protein concentrations is suggested, based on the temperature- and concentration-dependent dissociation of the beta-lactoglobulin dimer and an associated conformational transition. The position of the maximum in the thermogram has a marked dependence on the rate of heating down to the lowest rate investigated of 10 degrees C per hour, showing the importance of slow kinetic effects in the denaturation of this protein.

Synthesis of an infectious full-length cDNA clone of rice yellow mottle virus and mutagenesis of the coat protein

A full-length cDNA clone of rice yellow mottle sobemovirus (RYMV) was synthesized and placed adjacent to a bacteriophage T7 RNA polymerase promoter sequence. Capped-RNA transcripts produced in vitro were infectious when mechanically inoculated onto rice plants (Oryza sativa L). Individual full-length clones varied in their degree of infectivity but all were less infectious than native viral RNA. A representative clone, designated RYMV-FL5, caused a disease phenotype identical to that produced by viral RNA except that symptoms were somewhat slower to appear than those induced by viral RNA. The infectivity of RYMV-FL5 was verified by ELISA, Western blot analysis, Northern blot hybridization, RT-PCR, and Southern blot hybridization. Frameshift and deletion mutations introduced into the coat protein cistron demonstrated that the coat protein was dispensable for RNA replication in rice protoplasts. However, the coat protein was required for full infectivity in rice plants, presumably by playing a role in phloem-mediated long-distance movement and possibly in cell-to-cell movement.

Discrimination of species in the genus Listeria by Fourier transform infrared spectroscopy and canonical variate analysis

Infrared spectra of type cultures of the six recognized species of the genus Listeria and of Listeria grayi subsp. murrayi were recorded. By use of a library of 59 spectra, comprising at least six replicates of each type, discrimination by canonical variate analysis of the spectral amplitudes allowed all of the spectra to be correctly classified.

Reproducibility of computer-aided semen analysis: comparison of five different systems used in a practical workshop

STUDY OBJECTIVES

To assess a single (donor) sample by the use of five computer-assisted semen analysis (CASA) systems.

SETTING

British Andrology Society advanced course on computer-assisted semen analysis techniques, September 1992.

PARTICIPANTS

Clinical, technical and scientific personnel with mixed experience of CASA techniques, but all interested in semen assessment technology.

RESULTS

22 sets of data, comprising 6 commonly derived parameters, from the same sample were obtained using five CASA systems. The coefficients of variation for sperm concentration (29%) and proportion motile (24%) were comparable to those previously reported for manual assessments. For all parameters, "within system" variability was considerably greater than "between system," indicating that differences in sample handling and operator expertise were more significant sources of variation than the CASA systems themselves.

CONCLUSIONS

Emphasis on operator training and standardization of sample handling techniques would enhance the reproducibility of CASA measurements more than improvements in the CASA systems themselves. There was evidence, however, that the CASA measurements were more consistent than equivalent manual measures, and also provide information about the quality of sperm motility which cannot be obtained by alternative techniques.

The secondary structure of milk proteins and their biological function

A brief overview is given of the methods of determining and predicting secondary structure in proteins. The secondary structures of the milk serum proteins, lactoferrin, alpha-lactalbumin, lysozyme, and beta-lactoglobulin, as determined by x-ray crystallography, are compared with the results of a joint prediction method. This comparison evaluates critically the degree of success achieved and helps define what can reasonably be expected from a prediction in the absence of a known structure. The value of supplementary information from spectroscopic methods and the use of templates and sequence information from related proteins in improving the confidence of predictions are illustrated. One point that emerges is the general overprediction of helix content by the joint prediction method such that, for an all-beta protein such as beta-lactoglobulin, the method of Garnier, Osguthorpe, and Robson, applied with the correctly selected decision constants, provides a somewhat better approach. Secondary structure of the caseins can be predicted with less confidence than for globular proteins, and the results should be interpreted as evidence of a propensity to form transient secondary structures of the indicated type in view of the generally open and flexible conformation of caseins in solution.

Interrelationships of the concentrations of some ionic constituents of human milk and comparison with cow and goat milks

1. Milk and milk ultrafiltrate samples from four women (Homo sapiens) during the first 16 weeks of lactation were analysed for the main salt constituents, protein and lactose and the interrelationships of these constituents were determined. 2. A good positive correlation was observed between ultrafiltrate calcium and citrate concentrations, as previously observed for cow (Bos taurus) and goat (Capra hircus) milk but the expected negative correlation of lactose with ultrafiltrate salts was poor. 3. An invariant ion activity product for milk calcium phosphate was found for a dicalcium phosphate stoichiometry but the milk serum was less supersaturated with respect to calcium phosphate and citrate salts than ruminant milks. 4. The observed interrelationships are discussed in relation to the constraints on human milk composition arising from a fixed osmotic pressure, overall charge neutrality and saturation with respect to calcium phosphate.

Precocious pathfinding: retinal axons can navigate in an axonless brain

The developing axons of retinal ganglion cells follow a stereotyped trajectory through the diencephalon to the optic tectum. In Xenopus, this trajectory closely parallels that of a preexisting fiber tract, the tract of the postoptic commissure (TPOC). This tract comprises part of the early CNS scaffold and has been proposed to play a critical role in guiding the later growing optic axons. We have tested this possibility using heterochronic and xenoplastic transplants of eye primordia to force optic axons to enter the brain before scaffold tracts have arisen in the forebrain. We show that optic axons can navigate appropriately in the absence of the TPOC or any other axons, indicating that axonal pathfinding cues are present in the axonless neuroepithelial sheet. We suggest that molecularly distinct heterogeneities within the neuroepithelium are used for pathfinding by early and late developing axons alike in normal development.

Major psychological disorders in chronic TMD patients: implications for successful management

The authors assessed psychological disorders in 50 chronic TMD patients. These disorders appear to be a major concomitant factor in chronic TMD, and may need to be treated for successful outcomes.

Long term follow-up of agoraphobics treated by brief intensive group cognitive behavioural therapy

This study reports the long term efficacy of a brief intensive (2 days) group cognitive behavioural programme for the treatment of agoraphobia with panic attacks. A total of 97 patients was included in the study. Seventy-four patients were in the treated group and 23 were on the waiting list control group. The Fear Questionnaire (FQ), Fear Survey Schedule (FSS), Maudsley Personality Inventory (MPI), the Hostility and Direction of Hostility Questionnaire (HDHQ) and a clinical assessment based on structured interview to assess current levels of functioning were used as dependent measures. The results show that patients in the treated group show significant improvement on FSS and FQ when compared with the patients in the control group. Clinical rating shows that 85% of the patients were either symptom free or their symptoms had been reduced and these effects of treatment were shown to be maintained at follow-up which was on average 1 year after the treatment.

Cephalic expression and molecular characterization of Xenopus En-2

We have isolated and characterized cDNAs corresponding to the Xenopus En-2 gene. Comparison of amino acid sequences between the entire Xenopus En-2 and the Drosophila engrailed proteins confirms conservation of sequences inside as well as proximal to the homeobox and reveals a region of similarity towards the N terminus. Two transcripts encode the Xenopus En-2 protein. Both transcripts are regulated temporally in an identical fashion and are likely to be transcribed from two copies of the En-2 gene. We have also analyzed the distribution of the protein in the head tissue and in the dissected brain of tailbud stage embryos. In addition to the main band of expression at the midbrain-hindbrain boundary, we show that the protein is expressed in three novel areas: the mandibular arch, the optic tectum and the region of anterior pituitary.

Calcium environment in encrusting deposits from urinary catheters investigated by interpretation of EXAFS spectra

Extended x-ray absorption fine structure (EXAFS) spectra were recorded, above the K absorption edge of Ca, from 10 encrusted urinary (Foley) catheters obtained from 10 different patients. The presence of poorly crystalline apatite was demonstrated in all the deposits, even though this phase could not be detected in the x-ray powder diffraction patterns of most samples because of the obscuring effect of struvite, which was also present. Furthermore, the EXAFS spectra could be interpreted to yield quantitative information on the average short-range structure surrounding the Ca2+ ions in the poorly crystalline apatite.

Effects of intraocular tetrodotoxin on the development of the retinocollicular pathway in the Syrian hamster

The developing uncrossed retinocollicular projection in the Syrian hamster undergoes a characteristic set of changes during the first 2 postnatal weeks. The retinal fibres, which initially project across the whole superior colliculus, withdraw from the caudal part and their terminals become clustered into deep, discrete clumps rostrally. Coincident with these afferent changes, there is substantial retinal ganglion cell death. To examine whether neuronal activity plays a role in these changes, we made daily injections of the sodium channel blocker tetrodotoxin (TTX) into one or both eyes from postnatal day 2 or 4 up to day 12. Following TTX treatment, the uncrossed terminals retracted on schedule from the caudal and superficial parts of the superior colliculus and came to lie, as normal, in the deep layers rostrally. Within the rostral superior colliculus, however, the uncrossed terminals from TTX-injected eyes lost their characteristic patchy distribution and were arranged diffusely. When only one eye received TTX injections, this inhibiting effect on terminal segregation was seen only in the projections from the TTX-treated eye. The effect of TTX treatment on terminal segregation was much less severe than that of unilateral enucleation, after which uncrossed terminals persis throughout the entire superior colliculus. TTX injections appeared to have little effect on overall ganglion cell death since the total number of ganglion cells in the crossed projection from TTX-treated eyes was similar to that in normal eyes. However, the relative distribution of uncrossed cells in temporal and nasal retina was altered. In eyes that received TTX injections, the proportion of uncrossed cells in nasal retina was about 1.6 times that in normal animals and was close to the proportion seen in unilaterally enucleated animals. This increase in the treated eye occurred whether one or both eyes were injected with TTX. We conclude that neuronal activity plays a role in the segregation of uncrossed terminals into discrete clumps in rostral colliculus and in the preferential elimination of uncrossed cells from the nasal retina. The inactive uncrossed projections from TTX-treated eyes showed the greatest degree of disruption. The extent of the disruption was similar whether the crossed input from the other eye was active or inactive. This suggests that the activity-drive interactions between ganglion cells within one eye are more significant than those between the two eyes in shaping the final form of the uncrossed retinocollicular projection.

FBL-reactive CD8+ cytotoxic and CD4+ helper T lymphocytes recognize distinct Friend murine leukemia virus-encoded antigens

Immunization of C57BL/6 (B6) mice with FBL, a Friend murine leukemia virus (F-MuLV), induces both tumor-specific cytolytic CD8+ (CTL) and lymphokine-producing CD4+ Th that are effective in adoptive therapy of B6 mice bearing disseminated FBL leukemia. The current study evaluated the F-MuLV antigenic determinants expressed on FBL that are recognized by FBL-reactive CD8+ and CD4+ T cells. To identify the specificity of the FBL-reactive CD8+ CTL, Fisher rat embryo fibroblast (FRE) cells transfected with plasmids encoding F-MuLV gag or envelope (env) gene products plus the class I-restricting element Db were utilized. FBL-reactive CTL recognized FRE target cells transfected with the F-MuLV gag-encoded gene products, but failed to recognize targets expressing F-MuLV env. Attempts to generate env-specific CD8+ CTL by immunization with a recombinant vaccinia virus containing an inserted F-MuLV env gene were unsuccessful, despite the generation of a cytolytic response to vaccinia epitopes, implying that B6 mice fail to generate CD8+ CTL to env determinants. By contrast, CD4+ Th clones recognized FRE target cells transfected with env and not gag genes, and immunization with the recombinant vaccinia virus induced an env-specific CD4+ T cell response. These data show that in a Friend retrovirus-induced tumor model in which tumor rejection can be mediated by either CTL or Th, antigens derived from discrete retroviral proteins are predominantly responsible for activation of each T cell subset.

Primary and predicted secondary structures of the caseins in relation to their biological functions

In free solution, the caseins behave as non-compact and largely flexible molecules with a high proportion of residues accessible to solvent. Historically, they have been described as random coil-type proteins with only a nutritional function. Nevertheless, secondary structure prediction algorithms indicate that many parts of the (unphosphorylated, unglycosylated) polypeptide chains can form regular structures. In particular, a recurrent motif of the Ca2+-sensitive caseins in man, rat, mouse, guinea pig and ruminant species is an alpha-helix--loop--alpha-helix conformation in which the loop region typically contains a cluster of sites of phosphorylation. The biological function of the caseins is considered and it is suggested that the potential or actual conformations of the group of Ca2+-sensitive caseins are suited to the function of modulating the precipitation of calcium phosphate from solution. Either they can act as sites for nucleation or they can bind rapidly to calcium phosphate nuclei as they form spontaneously from supersaturated solution.

Casein and lactose concentrations in milk of 31 species are negatively correlated

Casein and lactose concentrations in milks of various species vary by at least 1-2 orders of magnitude, yet no single species secretes both components at either the high or the low end of the ranges. This pattern of variation could result from evolutionary adaptations in a single secretory mechanism.

Hypokalemia-induced psychosis in a chronic schizophrenic patient

An association is documented between hypokalemia and an acute psychotic decompensation in a patient with chronic schizophrenia. The patient's symptom picture and other aspects of the clinical presentation alone were not sufficient to differentiate between hypokalemic psychosis and an exacerbation of schizophrenia. A restricted focus on a history of psychosis, ignoring the possibility of organic factors, can be misleading and dangerous to the patient.