Dominant-negative inhibition of prion formation diminished by deletion mutagenesis of the prion protein

Polymorphic basic residues near the C terminus of the prion protein (PrP) in humans and sheep appear to protect against prion disease. In heterozygotes, inhibition of prion formation appears to be dominant negative and has been simulated in cultured cells persistently infected with scrapie prions. The results of nuclear magnetic resonance and mutagenesis studies indicate that specific substitutions at the C-terminal residues 167, 171, 214, and 218 of PrP(C) act as dominant-negative, inhibitors of PrP(Sc) formation (K. Kaneko et al., Proc. Natl. Acad. Sci. USA 94:10069-10074, 1997). Trafficking of substituted PrP(C) to caveaola-like domains or rafts by the glycolipid anchor was required for the dominant-negative phenotype; interestingly, amino acid replacements at multiple sites were less effective than single-residue substitutions. To elucidate which domains of PrP(C) are responsible for dominant-negative inhibition of PrP(Sc) formation, we analyzed whether N-terminally truncated PrP(Q218K) molecules exhibited dominant-negative effects in the conversion of full-length PrP(C) to PrP(Sc). We found that the C-terminal domain of PrP is not sufficient to impede the conversion of the full-length PrP(C) molecule and that N-terminally truncated molecules (with residues 23 to 88 and 23 to 120 deleted) have reduced dominant-negative activity. Whether the N-terminal region of PrP acts by stabilizing the C-terminal domain of the molecule or by modulating the binding of PrP(C) to an auxiliary molecule that participates in PrP(Sc) formation remains to be established.

Dieldrin resistance in Lucilia cuprina (the australian sheep blowfly): chance, selection and response

Discrete-generation population cages of Lucilia cuprina were initiated with dieldrin-resistant allele (Rdl ) frequencies of 1 or 5% and maintained for 17 generations on media with concentrations of dieldrin in the range 0-0.006% (w/v). The probability of the initial establishment of the Rdl allele in a population was consistently greater at the 5% frequency and dependent on the concentration of dieldrin in the medium for both starting frequencies. Once the resistant allele was established responses to selection were concentration-dependent. It was concluded that in the absence of dieldrin the susceptible allele was selectively favoured, at 0. 00005% (w/v) concentration selection and random genetic drift influenced changes in allele frequency and at concentrations above this the Rdl allele was at a selective advantage. Fixation of Rdl occurred at the higher concentrations. The influence of random genetic drift and selection on the genetic response during the evolution of insecticide resistance is discussed.

The effect of maternal exposure to flaxseed on spermatogenesis in F(1) generation rats

Pregnant Sprague-Dawley rats were exposed to a flaxseed (20 or 40%), flaxmeal (13 or 26%) or standard NIH AIN-93 (0% flaxseed control) diet throughout gestation and until their offspring were weaned. After weaning, F(1) generation males were placed in the same diet treatment groups as their mothers for 70 days. Statistically significant differences were not observed between either low-dose or high-dose flaxseed and flaxmeal-treated animals and the 0% flaxseed control animals for testis weights, homogenization resistant spermatid counts, daily sperm production rates, epididymal weights, seminal vesicle weights, seminiferous tubule fluid testosterone concentrations and the percentage of sperm abnormalities. The following statistically significant differences were observed when treated groups and the 0% flaxseed control groups were compared: (1) increases in serum LH in the 20% and 40% flaxseed treatment groups and in serum LH and testosterone in the 26% flaxmeal treatment group; (2) increases in the cauda epididymal weight from the 20% and 40% flaxseed groups; (3) increases in cauda epididymal sperm numbers/g epididymis from the 20% and 40% flaxseed and the 13% and 26% flaxmeal treatment groups; (4) a decrease in prostatic weight from the 20% flaxseed and 13% and 26% flaxmeal treatment groups. Prostate weight in the 40% flaxseed treatment group was lower but not statistically significantly different than the 0% flaxseed control group. Histological effects on spermatogenesis were not observed in either the control group, flaxmeal or the flaxseed treated groups.

Combined intraportal infusion of acetylcholine and adrenergic blockers augments net hepatic glucose uptake

Portal glucose delivery in the conscious dog augments net hepatic glucose uptake (NHGU). To investigate the possible role of altered autonomic nervous activity in the effect of portal glucose delivery, the effects of adrenergic blockade and acetylcholine (ACh) on hepatic glucose metabolism were examined in 42-h-fasted conscious dogs. Each study consisted of an equilibration (-120 to -20 min), a control (-20 to 0 min), and a hyperglycemic-hyperinsulinemic period (0 to 300 min). During the last period, somatostatin (0.8 microg. kg(-1). min(-1)) was infused along with intraportal insulin (1.2 mU. kg(-1). min(-1)) and glucagon (0.5 ng. kg(-1). min(-1)). Hepatic sinusoidal insulin was four times basal (73 +/- 7 microU/ml) and glucagon was basal (55 +/- 7 pg/ml). Glucose was infused peripherally (0-300 min) to create hyperglycemia (220 mg/dl). In test protocol, phentolamine and propranolol were infused intraportally at 0.2 microg and 0.1 microg. kg(-1). min(-1) from 120 min on. ACh was infused intraportally at 3 microg. kg(-1). min(-1) from 210 min on. In control protocol, saline was given in place of the blockers and ACh. Hyperglycemia-hyperinsulinemia switched the net hepatic glucose balance (mg. kg(-1). min(-1)) from output (2.1 +/- 0.3 and 1.1 +/- 0.2) to uptake (2.8 +/- 0.9 and 2.6 +/- 0.6) and lactate balance (micromol. kg(-1). min(-1)) from uptake (7.5 +/- 2.2 and 6.7 +/- 1.6) to output (3.7 +/- 2.6 and 3.9 +/- 1.6) by 120 min in the control and test protocols, respectively. Thereafter, in the control protocol, NHGU tended to increase slightly (3.0 +/- 0.6 mg. kg(-1). min(-1) by 300 min). In the test protocol, adrenergic blockade did not alter NHGU, but ACh infusion increased it to 4.4 +/- 0.6 and 4.6 +/- 0.6 mg. kg(-1). min(-1) by 220 and 300 min, respectively. These data are consistent with the hypothesis that alterations in nerve activity contribute to the increase in NHGU seen after portal glucose delivery.

Intermediate sanctions: tax traps for the unsuspecting

In an effort to keep your CEO from leaving, your board is overly generous--with salary, benefits, and perks. But if that generosity goes far beyond the norm for your region and type of organization, you could be letting your CEO and fellow trustees in for some very stiff penalties.

Activation of apoptosis-linked caspase(s) in NMDA-injured brains in neonatal rats

Unilateral injection of 50 nmol of N-methyl-D-aspartate (NMDA) into the left posterior striatum of 7 day-old rat pups induces massive neuronal loss in the ipsilateral hemisphere in 5 days. In this model of excitotoxicity, the form of neuronal death (necrosis vs apoptosis) has not been clearly addressed. Here we report evidence of DNA laddering in the ipsilateral hemisphere 24 h after the NMDA injection. Activation of apoptosis-linked caspase(s) was also identified, as evidenced by (i) the formation of caspase-produced 120 kDa alpha-spectrin breakdown product (SBDP120) and (ii) increase in hydrolysis of caspase-3 substrate acetyl-DEVD-7-amido-4-methylcoumarin in the homogenate from the ipsilateral hemisphere. Lastly, we note that i.p. injection (100 mg/kg) of a pan caspase inhibitor Z-D-DCB attenuates the levels of SBDP120. Our results suggest the presence of caspase-activation in this rat pup model of NMDA toxicity.

Cost effectiveness of omeprazole and ranitidine in intermittent treatment of symptomatic gastro-oesophageal reflux disease

OBJECTIVE

This 1-year study compared the cost effectiveness of omeprazole and ranitidine when used as initial therapy in an intermittent treatment strategy for the management of patients with symptomatic gastro-oesophageal reflux disease with or without erosive oesophagitis.

DESIGN AND SETTING

A prospective health economic analysis was conducted alongside an international multicentre randomised, double-blind clinical study. The economic analysis was performed from a societal perspective.

PATIENTS

A total of 704 patients in the UK, the Republic of Ireland, Germany, France, Italy and Spain were randomised to 1 of the 3 treatment groups.

INTERVENTIONS

Patients were randomised to receive either omeprazole 20 mg once daily, omeprazole 10 mg once daily or ranitidine 150 mg twice daily. Initial treatment failure resulted in dose titration and drug switching from ranitidine to omeprazole, and subsequently open maintenance treatment.

MAIN OUTCOME MEASURES AND RESULTS

The estimated mean direct medical costs (medication and number of visits and endoscopies) were found to be lower for both dosages of omeprazole than for ranitidine in all countries except Germany. However, none of the differences were statistically significant. The differences between omeprazole 10 mg and omeprazole 20 mg were small and nonsignificant. With regard to numbers of symptom-free days, both omeprazole 20 mg and omeprazole 10 mg were found to be more effective than ranitidine. However, none of the differences were statistically significant.

CONCLUSIONS

Following a pragmatic interpretation, incorporating intermediate short term results, the results in this study give no support to the notion that a step-up approach, either as dose titration from omeprazole 10 mg to omeprazole 20 mg or as drug switching from ranitidine to omeprazole, will result in cost savings and thereby be cost effective.

Outcome of colectomy for slow transit constipation

OBJECTIVE

To review the outcome data for colectomy performed for patients with slow transit constipation (STC).

BACKGROUND

The outcome of surgical intervention in patients with STC is unpredictable. This may be a consequence of the lack of effectiveness of such interventions or may reflect heterogeneity within this group of patients.

METHODS

The authors reviewed the data of all series in the English language that document the outcome of colectomy in > or = 10 patients in the treatment of STC.

RESULTS

Thirty-two series fulfilled the entry criteria. There was widespread variability in patient satisfaction rates after colectomy (39% to 100%), reflecting large differences in the incidence of postoperative complications and in long-term functional results. Outcome was dependent on several clinical and pathophysiologic findings and on the type of study, the population studied, and the surgical procedure used.

CONCLUSIONS

It may be possible to predict outcome on the basis of preoperative clinical and pathophysiologic findings. This review suggests a rationale for the selection of patients for colectomy.

International reference reagents: antihuman globulin. An ISBT/ICSH joint working party report. International Society of Blood Transfusion. International Committee for Standardization in Haematology

An international working party has conducted a study designed to select a suitable reference reagent for antihuman globulin, to replace those first made available in 1987. The chosen preparation contains levels of anti-IgG and anti-C3 (anti-C3c and anti-C3d) potency that are considered suitable to serve for reference when evaluating either polyspecific antihuman globulin reagents or those containing their separate monospecific components. The reference material is available in 2-ml freeze-dried aliquots from seven assigned distribution centres.

Th1 cytokine patterns in cervical human papillomavirus infection

The host's immune response to cervical human papillomavirus (HPV) infection is poorly understood. In a longitudinal cohort of women with cervical HPV infections, defined by PCR-based HPV DNA testing, we used exfoliated cervical cells and reverse transcription-PCR to examine the cervical mucosal mRNA expression of cytokines involved in regulating cell-mediated immunity. We identified seven HPV-positive subjects who were found to have cleared their HPV infections 4 months later. In all seven, a T-helper type 1 (Th1) cytokine pattern (expression of gamma interferon and absence of interleukin-4) preceded clearance. The more variable cytokine patterns seen in HPV-negative subjects suggest that the Th1 pattern in the women with subsequent clearance was a response to the HPV infection. This contention is supported by additional cross-sectional data showing a Th1 pattern in a majority of HPV-positive women. This study establishes a feasible means for assessing local cytokine expression in the cervical milieu and demonstrates that a Th1 cytokine response is associated with subsequent clearance of cervical HPV infection.

HIV case loads of Australian GPs. Results of the national survey

BACKGROUND

This paper presents national survey data concerning the management of HIV positive patients by GPs.

OBJECTIVE

To examine the extent and nature of GPs' involvement in the management of patients with HIV/AIDS; to identify their needs for education and support.

DISCUSSION

Some GPs have never been consulted by an HIV positive patient, some have no current cases, others have either low or higher case loads. GPs in the first two categories had difficulty maintaining interests and skills in HIV. Those with low case loads recognised limitations in HIV management, relying on the skills of consultants or specialist GPs, and rationalizing CME time according to their current patients. GPs with higher case loads tended to manage full care of their HIV positive patients, to be authorized s100 prescribers, to be members of the Australasian Society for HIV Medicine, to have attended an HIV specific CME course, and to practise in an inner urban area.

A comparison of CD34+ cell selected and unselected autologous peripheral blood stem cell transplantation for multiple myeloma: a case controlled analysis

Following ASCT for multiple myeloma, it is unclear whether relapse is due solely to the presence of residual myeloma cells after myeloablation, or whether it is in part attributable to contamination of the stem cell harvest with viable malignant cells. Positive selection of CD34+ cells markedly reduces plasma cell contamination. We performed a case controlled analysis in which 15 patients with myeloma who underwent autologous PBSCT with CD34+cell selection using the Ceprate System (index group), were compared with 15 matched controls. All subjects received an identical preparative regimen. The median times to neutrophils >/=0.5 x 10(9)/l and unsupported platelets >/=50 x 10(9)/l were 14 and 23 days for the CD34+cell selected group and 11 (P = 0.03) and 14 (P = 0.029) for the case controls. Median follow-up of purged patients from autologous PBSCT was 32 months (range 18-43). At 36 months, the probability of PFS was 47 +/- 14% and 46 +/- 14% in the index and control groups (P = 0.44). The 3 year probability of OS was 69 +/- 13% for the CD34+ cell selected arm and 66 +/- 12.4% in unpurged patients (P = 0.91). Median PFS for the cell selected group is 24 months (CI 19.1-36.0), and 29 months for controls (CI 7.1-50.9). Eleven patients undergoing cell selection remain alive, seven of whom are progression free. At the same time-point after unpurged autologous PBSCT, the corresponding figures are 12 patients alive, with seven remaining progression free. Autologous PBSCT with CD34+ cell selection is both feasible and safe, but results in delayed engraftment as compared to case controls. The 3 year probability of PFS and OS in the cell selected arm was similar to that of the unpurged controls. Our findings indicate that autologous PBSCT with CD34+ cell selection appears not to have any favourable effect on disease progression. However, the results of this case controlled analysis should be cautiously interpreted, and the role of CD34+ selection in autologous PBSCT should be further investigated by large randomised trials.

Growth inhibition of Candida albicans by vaginal cells from naïve mice

Recurrent vulvovaginal candidiasis (RVVC) is a common idiopathic mucosal infection caused by Candida albicans. Current data suggests that local immunity is more important than that in the peripheral circulation for protection against infection. In the present study, anti-Candida innate resistance at the vaginal mucosa was investigated using a murine model. For this, splenic and vaginal cells were assessed for in vitro growth inhibition (GI) of C. albicans and cytotoxicity of natural killer (NK) cell-sensitive tumour targets (YAC-1). As expected, significant GI of C. albicans by splenic cells was mediated predominantly by polymorphonuclear leucocytes (PMNL) at effector to target (E:T) ratios of 100 and 50:1. From the vaginal mucosa, naïve unfractionated, but not nylon wool non-adherent (NWN), cells extracted from whole vaginal tissue showed significant GI of C. albicans at E:T ratios as low as 1:1, but only modest killing of YAC-1 targets at all E:T ratios. Subsequent experiments showed significant GI of C. albicans by vaginal epithelioid-enriched cells and with several epithelial cell lines, but not in supernatants collected from the co-cultures. In contrast, lymphoid cell lines had no anti-Candida activity. These results suggest that anti-Candida activity is present at the vaginal mucosa, but unlike that from the spleen, the vaginal activity appears to be predominantly mediated by epithelial cells.

Involving men in reproductive health: the Young Men's Clinic

OBJECTIVES

This report describes the population of young men who use the Young Men's Clinic in New York City, presents a profile of their reproductive behaviors, and describes the clinic's model of service delivery.

METHODS

Data were gathered through a routine clinic visit form administered by clinic staff.

RESULTS

The clinic sees approximately 1200 predominately Dominican young men each year for a wide range of clinical and mental health services. Two thirds of clients had ever been sexually active, three quarters had ever used birth control, and 69% had used birth control at their last sexual encounter.

CONCLUSIONS

The Young Men's Clinic may serve as a model for health care delivery to adolescent and young adult males.

Comparison of colour Doppler imaging of orbital vessels in elderly compared with young adult patients

PURPOSE

Colour Doppler imaging provides an estimate of the velocity of blood flow in vessels supplying the eye.

METHODS

To assess changes in orbital blood flow with age, we used a method to study peak systolic velocity in 20 young normal patients, mean age 25.2+/-2.4 years and 30 elderly normal patients, mean age 69.5+/-7.9 years.

RESULTS

Peak systolic velocity was significantly higher in the central retinal artery and the temporal division of the posterior ciliary artery in elderly patients. There was greater variation in the peak systolic velocity readings in the distal part of the ophthalmic artery in the elderly than in the younger group. There was greater variation in the pulsatility index in the central retinal artery in young subjects.

CONCLUSIONS

Though not large, these differences suggest changes in the orbital blood vessels with age which could affect the development of disease processes in elderly patients. These changes should be taken into account when assessing blood flow in elderly patients.