Infertility in mice induced by a recombinant ectromelia virus expressing mouse zona pellucida glycoprotein 3

Population control has become a major problem in many wildlife species. Fertility control through immunocontraception has been proposed as a method for reducing population size. We have tested the concept that immunocontraception can be achieved with a recombinant ectromelia virus expressing an ovary-specific antigen, the mouse zona pellucida 3 (ZP3) glycoprotein. Female mice infected with the recombinant virus produced autoimmune antibodies against ZP3 and were infertile for 5-9 mo after infection. For almost half the infertile mice, immunity to ZP3 was associated with a disruption of ovarian follicular development and the depletion of mature follicles without observable oophoritis. Mice returned to fertility as the anti-ZP3 antibody level in the serum decreased. Reinfection of the mice with the recombinant virus boosted the anti-ZP3 response and restored infertility.

A prokaryotic-like mode of cytoplasmic eukaryotic ribosome binding to the initiation codon during internal translation initiation of hepatitis C and classical swine fever virus RNAs

Initiation of translation of hepatitis C virus and classical swine fever virus mRNAs results from internal ribosomal entry. We reconstituted internal ribosomal entry in vitro from purified translation components and monitored assembly of 48S ribosomal preinitiation complexes by toe-printing. Ribosomal subunits (40S) formed stable binary complexes on both mRNAs. The complex structure of these RNAs determined the correct positioning of the initiation codon in the ribosomal "P" site in binary complexes. Ribosomal binding and positioning on these mRNAs did not require the initiation factors eIF3, eIF4A, eIF4B, and eIF4F and translation of these mRNAs was not inhibited by a trans-dominant eIF4A mutant. Addition of Met-tRNAiMet, eIF2, and GTP to these binary ribosomal complexes resulted in formation of 48S preinitiation complexes. The striking similarities between this eukaryotic initiation mechanism and the mechanism of translation initiation in prokaryotes are discussed.

Hypospadias trends in two US surveillance systems

OBJECTIVE

Hypospadias is a common congenital anomaly, the cause of which is unknown. Unexplained increases in the rates of hypospadias occurred in five European countries in the 1970s and 1980s. We examined data from two birth defects surveillance systems in the United States for evidence of similar trends.

METHODOLOGY

The Metropolitan Atlanta Congenital Defects Program (MACDP) provided birth prevalence rates from 1968 to 1993. The nationwide Birth Defects Monitoring Program (BDMP) provided rates from 1970 to 1993. MACDP data are population-based and could be categorized by the severity of the hypospadias. BDMP data allowed analysis of rate trends for the four census regions of the United States.

RESULTS

Data from both surveillance systems showed an approximate doubling of hypospadias rates in the 1970s and 1980s. MACDP data showed that the rate of severe cases increased while the ratio of mild to severe cases decreased. BDMP data showed that hypospadias rates increased markedly in all four regions of the United States.

CONCLUSIONS

The observed increases are unlikely to be attributable to increased sensitivity of the surveillance systems or the identification of more mild cases by physicians over time, because either trend would have increased rather than decreased the ratio of mild to severe cases. If real, these trends represent the largest number of cases and the first report of an increase in hypospadias rates outside of Europe. Additional investigation of a possible increase in hypospadias rates is warranted.

Gum health product formulations: what is in them and why?

Two dominant factors dictate which ingredients are used in formulating toothpaste and mouthwashes. The major one is the type of active ingredient chosen, especially cationic active ingredients such as chlorhexidine; the other factor is the needs of the consumer. Apart from gum health benefits, the consumer expects to obtain from gum health toothpaste and mouthwashes other benefits of clean teeth (abrasive and detergent), fresh breath (antimicrobial agents and flavor) and protection from caries and possibly tartar. Exhaustive testing involving experimental design and validated laboratory and clinical tests is essential to ensure that all these benefits are delivered. Unless products are developed systematically, then products with relatively poor activity can find their way on to the market.

Childhood Lead Poisoning in Russia: A Site-specific Pediatric Blood Lead Evaluation

Lead poisoning in children is an international concern. Health effects vary according to a child's blood lead level. Historically, the problem of lead poisoning in Russia had been defined by analysis of hair samples. In Saratov, Russia, during the spring of 1996, the authors conducted the first evaluation of blood lead levels among Russian children. The mean blood lead level of 579 samples analyzed at the Centers for Disease Control and Prevention was 7.7 µg/dL (range 3.0 to 35.7 µg/dL). The sensitivity of hair analysis in identifying blood lead levels above 10 µg/dL was 50%. Most of the environmental samples evaluated (including water, dust, paint, and soil) were within acceptable U.S. remediation standards. Almost one-fourth of the Russian children evaluated during this site-specific investigation had blood lead levels capable of causing adverse health effects in children. Hair analysis is not an adequate method for identifying these children. Additional investigations in other Russian cities are necessary in order to determine the extent of lead poisoning in Russia's children.

Reproductive toxins and alligator abnormalities at Lake Apopka, Florida

The alligator population at Lake Apopka in central Florida declined dramatically between 1980 and 1987. Endocrine-disrupting chemicals and specifically DDT metabolites have been implicated in the alligators' reproductive failure. The DDT metabolite hypothesis is based largely on the observation of elevated concentrations of p,p-DDE and p,p-DDD in alligator eggs obtained from Lake Apopka in 1984 and 1985. In the following commentary, we draw attention to two nematocides that are established reproductive toxins in humans, dibromochloropropane (DBCP) and ethylene dibromide (EDB), which could also have played a role in the reproductive failure observed in alligators from Lake Apopka in the early 1980s.

The role of anxiety sensitivity in the pathogenesis of panic: prospective evaluation of spontaneous panic attacks during acute stress

Expectancy theory posits that anxiety sensitivity may serve as a premorbid risk factor for the development of anxiety pathology (S. Reiss, 1991). The principal aim of the present study was to determine whether anxiety sensitivity acts as a specific vulnerability factor in the pathogenesis of anxiety pathology. A large, nonclinical sample of young adults (N = 1,401) was prospectively followed over a 5-week highly stressful period of time (i.e., military basic training). Anxiety sensitivity was found to predict the development of spontaneous panic attacks after controlling for a history of panic attacks and trait anxiety. Approximately 20% of those scoring in the upper decile on the Anxiety Sensitivity Index (R. A. Peterson & S. Reiss, 1987) experienced a panic attack during the 5-week follow-up period compared with only 6% for the remainder of the sample. Anxiety sensitivity also predicted anxiety symptomatology, functional impairment created by anxiety, and disability. These data provide strong evidence for anxiety sensitivity as a risk factor in the development of panic attacks and other anxiety symptoms.

The role of anxiety sensitivity in the pathogenesis of panic: prospective evaluation of spontaneous panic attacks during acute stress

Expectancy theory posits that anxiety sensitivity may serve as a premorbid risk factor for the development of anxiety pathology (S. Reiss, 1991). The principal aim of the present study was to determine whether anxiety sensitivity acts as a specific vulnerability factor in the pathogenesis of anxiety pathology. A large, nonclinical sample of young adults (N = 1,401) was prospectively followed over a 5-week highly stressful period of time (i.e., military basic training). Anxiety sensitivity was found to predict the development of spontaneous panic attacks after controlling for a history of panic attacks and trait anxiety. Approximately 20% of those scoring in the upper decile on the Anxiety Sensitivity Index (R. A. Peterson & S. Reiss, 1987) experienced a panic attack during the 5-week follow-up period compared with only 6% for the remainder of the sample. Anxiety sensitivity also predicted anxiety symptomatology, functional impairment created by anxiety, and disability. These data provide strong evidence for anxiety sensitivity as a risk factor in the development of panic attacks and other anxiety symptoms.

The protective role of gastric acidity in neonatal bacterial translocation

The acid environment of the stomach serves as an important defense against intestinal colonization by potentially pathogenic bacteria. The purpose of this study was to examine the effect of increased gastric pH on bacterial translocation in a neonatal rabbit model. Fifty-nine rabbit pups were delivered by cesarean section and randomly divided into normal acid (NA) and reduced acid (RA) groups. All were gavage fed and challenged with Enterobacter cloacae, 1 x 10(6) CFU/mL. The RA group received ranitidine, 20 mg/kg/d with all feeds. Gastric pH was measured by pH probe before and 4 hours after bacterial challenge. Mesenteric lymph node (MLN), spleen, liver, midjejunum, and cecum were harvested for culture at 72 hours. Gastric pH in the RA group was significantly increased before and 4 hours after the bacterial challenge. The incidence of bacterial translocation to the MLN, spleen, and liver was significantly higher in the RA group. Log cecal and jejunal colony counts were significantly increased in the RA animals. The authors conclude that the gastric acidity is protective against intestinal colonization and translocation of potentially pathogenic bacteria in this neonatal rabbit model.

Is nasogastric tube decompression necessary after major abdominal surgery in children?

Nasogastric (NG) decompression has traditionally been used after major abdominal surgery in pediatric patients. This study was designed to determine if NG tubes could be routinely omitted in pediatric patients undergoing major abdominal procedures. Between January 1993 and December 1995, 83 patients had follow-up prospectively without NG decompression after a variety of major abdominal surgeries. NG tubes were inserted for persistent vomiting or abdominal distension. Exclusion criteria included bowel obstruction, intestinal atresia, and perforation of the stomach or duodenum. Ages ranged from 13 days to 22 years. Seventy-four patients (89%) were treated successfully without postoperative NG decompression. There were no cases of pneumonia, wound dehiscence, anastomotic leak, or delay in return of gastrointestinal function. Nine patients required NG tubes for persistent vomiting or abdominal distension. An anastomotic leak developed in one patient after endorectal pull-through. NG decompression is unnecessary after most major abdominal operations in pediatric patients. The endorectal pull-through may represent a group of patients that benefit from routine decompression.

Translational controls impinging on the 5'-untranslated region and initiation factor proteins

Translation of eukaryotic mRNAs is generally initiated by the scanning ribosome mechanism. This can be downregulated by high affinity protein binding to cap-proximal RNA motifs. Translation can also be regulated by short open reading frames within the 5' -untranslated region. A key factor for initiation is elF4F, in which one of the polypeptide chains, elF4G, seems to have a bridging function and binds three other factors at separate sites: elF4E (the cap-binding factor), the helicase elF4A, and elF3, which also interacts with 40S ribosomal subunits. Initiation is regulated by the MAP kinase and rapamycin-sensitive signalling pathways, which control phosphorylation of elF4E and 4E-BP1, a protein which in the dephosphorylated form binds and sequesters elF4E.

Life and death in the cytoplasm: messages from the 3' end

The cytoplasmic life of an mRNA revolves around the regulation of its localization, translation and stability. Interactions between the two ends of the mRNA may integrate translation and mRNA turnover. Regulatory elements in the region between the termination codon and poly(A) tail - the 3' untranslated region - have been identified in a wide variety of systems, as have been some of the key players with which these elements interact.

Dentine hypersensitivity and the placebo response. A comparison of the effect of strontium acetate, potassium nitrate and fluoride toothpastes

A considerable number of varied agents are apparently effective in the treatment of dentine hypersensitivity. In particular, the literature supports the efficacy of strontium, potassium and fluoride containing toothpastes. This study was a double-blind, randomised, parallel group comparison of three products, namely strontium- and potassium-based desensitising toothpastes both containing fluoride, and a conventional fluoride toothpaste. A total of 131 subjects entered a 4-week wash-in phase using the conventional fluoride toothpaste, of whom 120 entered a 6-week treatment phase. Sensitive teeth were evaluated at wash-in baseline, treatment baseline and after 2 and 6 weeks use of the treatment pastes. Dentine hypersensitivity was assessed with tactile and cold air stimuli together with an overall subjective assessment. Analysis of the findings was performed using non-parametric statistical methods. Of the original 120 subjects, 112 completed the trial. All 3 toothpaste groups showed reductions in sensitivity over the 6 weeks; however, no significant differences were found between the three products at any given time. Interestingly, there was no significant change in sensitivity between wash-in baseline and treatment baseline for the cold air stimulus with the fluoride-only-based paste. However, for the group using the same fluoride toothpaste, there was significant improvement between wash-in baseline and week 6, and treatment baseline and week 6 for this stimulus, suggesting a substantial placebo effect occurred. There is a need for further investigation of a wash-in period and examination of the placebo effect when evaluating dentine hypersensitivity trials.

Environmental public health surveillance

A holistic and collaborative approach needs to be taken in the development of environmental public health surveillance systems. Exposure and hazard surveillance integrated with outcome-based surveillance will blend fragmented strands of data into streams of information. Adequate resources and strong leadership are essential to the creation of such surveillance systems.

Oral but not parenteral interleukin (IL)-12 redirects T helper 2 (Th2)-type responses to an oral vaccine without altering mucosal IgA responses

Our past studies have shown that the mucosal adjuvant cholera toxin (CT) induces T helper type 2 (Th2) responses with systemic IgG1, IgE and mucosal secretory IgA (S-IgA) antibodies (Abs). In this study, recombinant murine IL-12 (rmIL-12) was given either parenterally or orally to mice orally immunized with tetanus toxoid (TT) and CT to determine whether this cytokine could redirect the CT-induced Th2-type responses and what effect this shift would have on S-IgA Ab responses. Intraperitoneal administration of rmIL-12 shifted TT-specific responses toward Th1-type and resulted in CD4+ T cells producing IFN-gamma and IL-2 with markedly reduced levels of Th2-type cytokines. This cytokine profile was accompanied by increased delayed-type hypersensitivity (DTH) and shifts in serum IgG1 to IgG2a and IgG3 anti-TT Ab responses. Further, serum IgE and S-IgA Ab responses were markedly reduced by parenteral IL-12. When IL-12 complexed to liposomes was given orally both shifts to IgG2a and IgG3 and low IgE Abs again occurred concomitant with enhanced serum IFN-gamma and DTH responses. Interestingly, oral rmIL-12 did not result in significant levels of serum IL-12 nor altered S-IgA Ab responses and resulted in higher levels of some Th2-type cytokines both in vitro and in vivo when compared with parenteral IL-12. Our results show that the shifts in systemic immune responses with intact S-IgA Abs which occur after oral delivery of IL-12-liposomes are due to cytokine effects in the Peyer's patches and suggest new strategies for the targeted manipulation of Th1- and Th2-type responses to mucosal vaccines.

Oral immunization with PspA elicits protective humoral immunity against Streptococcus pneumoniae infection

Streptococcus pneumoniae is a major respiratory mucosal pathogen affecting infants and children. Although a polysaccharide-based vaccine has been useful in adult populations, it does not elicit protective immunity in infants and young children. Pneumococcal surface protein A (PspA) is a highly immunogenic surface protein produced by all strains of Streptococcus pneumoniae. Previous studies have shown that systemic immunization of mice with PspA can elicit protective immunity against fatal pneumococcal infection. In this study, we demonstrated that oral immunization with PspA could elicit protective immune responses against pneumococcal infection. When mice were orally immunized with PspA alone, low levels of PspA-specific immunoglobulin G (IgG) responses were induced in serum; none was induced in secretion. On the other hand, when PspA was given orally with the mucosal adjuvant cholera toxin (CT), significant levels of IgG and IgA anti-PspA responses were induced in serum. The major IgG subclass was IgG1, followed by IgG2b, a profile of antibody response supported by Th2-type cells. In addition, all mice orally immunized with PspA and CT were protected from the lethal challenge with capsular serotype 3 S. pneumoniae A66. These results suggested that an oral PspA vaccine may be a useful means of preventing pneumococcal disease.

Identification and analysis of a collagenolytic activity in Streptococcus mutans

Streptococcus mutans is an important pathogen in coronal caries and is implicated in dental root decay by its ability to bind collagen from various sources. In the present study, electron microscopic analysis demonstrated the ability of S. mutans to bind and to disrupt collagen fibrils of the amniotic membrane. The synthetic peptide FALGPA, which is similar in structure to collagen, was degraded by S. mutans, with a lower level of FALGPA hydrolytic activity observed in sucrose-grown cells compared with cells grown in the absence of sucrose. Inhibition studies of FALGPA hydrolytic activity showed a pattern characteristic of collagenase activity, with inhibition by 1,10-phenanthroline and EDTA, but not by phenylmethylsulfonyl fluoride (PMSF). Additionally, immunological cross-reactivity was observed between proteins from disrupted cells of S. mutans and antiserum to collagenase from Clostridium histolyticum. Gelatinolytic activity was demonstrated by gelatin zymogram analysis. These findings suggest that collagenolytic activity by S. mutans may be an important virulence factor in dental root decay.

Effect of use of 0.05% cetylpyridinium chloride mouthwash on normal oral flora

OBJECTIVES

The aims of this study were to examine the effect of the use of a mouthwash containing 0.05% cetylpyridinium chloride (CPC) on (1) the composition of the normal oral microbial flora and (2) the establishment of non-oral bacterial species in the mouth.

METHOD

In a double-blind study, 129 subjects used, twice daily for 6 weeks, either a randomly assigned test or placebo mouthwash. At baseline and at the completion of the study, a sample of the oral flora was obtained by asking each subject to "swish" around the mouth for 30 s, 10 ml of distilled water. The numbers of total colony forming units (CFU), facultative bacteria, streptococci, mutans streptococci, lactobacilli, staphylococci, yeasts and enterococci were enumerated after culture on eight non-selective and selective media.

RESULTS

After 6 weeks use of either the test or placebo mouthwashes, there were no significant differences (analysis of variance) between the counts (CFU/ml of sample) for any of the microbial taxa.

CONCLUSIONS

These data indicate that the use of a CPC-containing mouthwash does not alter the composition of the normal oral flora or result in the establishment of non-oral and potentially pathogenic bacteria in the mouth.

Efficacy of a potassium nitrate mouthwash in alleviating cervical dentine sensitivity (CDS)

Potassium nitrate (KNO3) has been used previously in a dentifrice or gel to alleviate cervical dentine sensitivity (CDS). The aim of this study was to compare a 3% KNO3 Silica/NaF mouthwash with a NaF/silica mouthwash in a 6-week multi-centre double-blind study. 47 subjects (12M; 35F, mean age 36.2 (SD 11.46) years) participated in the study. Subjects were evaluated for tactile (Yeaple probe) and air sensitivity (dental air syringe) together with subjective perception of pain (0-10 scale) at 0, 2 and 6 weeks. Results for Yeaple probe (gm wt) (Wilcoxon paired rank test) between 6 weeks and baseline, were highly significant for both groups. Differences between groups at 6 weeks were statistically significant. Subjective Yeaple probe scores (paired t-tests) between 6 weeks and baseline were significant for both groups. There were no significant differences (unpaired t-tests) between groups over 6 weeks for subjective Yeaple probe scores. Subjective air scores (paired t-tests) between 6 weeks and baseline were significant for both groups. There were significant differences (unpaired t-tests) between groups in favour of the 3% KNO3/Silica/NaF group at 6 weeks. The 2 weeks and baseline results for both groups were the same as reported for 6 weeks and baseline. The results demonstrated that a 3% KNO3/Silica/NaF mouthwash compared to a Silica/NaF control significantly reduced CDS when evaluated by tactile and thermal stimuli. A 3% KNO3/silica/NaF mouthwash would, therefore appear to have therapeutic potential to alleviate CDS.

Interleukin-12 alters helper T-cell subsets and antibody profiles induced by the mucosal adjuvant cholera toxin

We have shown that systemic administration of rmIL-12 could trigger Th1-type responses to a protein antigen delivered orally with CT as mucosal adjuvant. The most striking finding was that IL-12 could retain its regulatory effects when orally administered and could redirect the immune response to the oral vaccine toward a Th1-type. However, regulation by orally administered IL-12 differed from parenteral treatment with IL-12 since only the latter treatment affected mucosal S-IgA responses. These findings have important implications for the development of mucosal vaccines that induce the desired immune response.

Unique features of internal initiation of hepatitis C virus RNA translation

The question of whether hepatitis C virus (HCV) RNA is translated by a mechanism of internal ribosome entry has been examined by testing whether insertion of HCV sequences between the two cistrons of a dicistronic mRNA promotes translation of the downstream cistron in rabbit reticulocyte lysates. Deletion analysis showed that efficient internal initiation required a segment of the HCV genome extending from about nucleotides 40-370 and that deletions from the 3'-end of this element were highly deleterious. As the authentic initiation codon for HCV polyprotein synthesis is at nucleotide 342, this demonstrates that, besides 5'-UTR sequences, a short length of HCV coding sequences is required for internal initiation. This finding was confirmed in transfection assays of BT7-H cells and was shown to be independent of the nature of the downstream reporter cistron. The strong requirement for coding sequences is in sharp contrast to internal initiation of picornavirus RNA translation. As a probable correlate with this, it was also found that the efficiency of internal initiation was only marginally compromised when the authentic initiation codon was mutated to a non-AUG codon, again in sharp contrast with the picornaviruses. The finding that coding sequences are required for internal initiation has important implications for the design of experiments to test for internal initiation of translation of cellular mRNAs.

Internal initiation of translation of hepatitis C virus RNA: the ribosome entry site is at the authentic initiation codon

Hepatitis C viral (HCV) RNA includes an internal ribosome entry segment (IRES) that extends some 30 nt into the coding region and promotes internal initiation of translation at the authentic initiation codon at nt 342. The 5'-boundary of this IRES was mapped by in vitro translation and transfection assays and was found to lie between nt 42 and 71. Within these IRES boundaries there are, in most HCV strains, three AUG triplets upstream of the authentic initiation site. Although the first, 5'-proximal, of these is absolutely conserved, a mutational analysis showed that it is not a functional initiation codon. In particular, the G residue could be substituted provided compensatory mutations were made to maintain base pairing. The other two upstream AUGs are not absolutely conserved, and mutation of the third (5'-distal) had little effect on IRES activity. When an additional AUG codon was introduced by single-site mutation just upstream of the authentic initiation codon, it was found to be used when most of the IRES had been deleted to generate an RNA translated by the scanning ribosome mechanism, but was not used in the background of the full-length IRES when internal initiation is operative. These results argue that the IRES promotes direct ribosome entry immediately at, or indeed very close to, the authentic initiation codon, and that the upstream AUGs do not serve as ribosome entry sites.

Comparison of 2 desensitizing dentifrices with a commercially available fluoride dentifrice in alleviating cervical dentine sensitivity

Previous studies have demonstrated efficacy of desensitizing dentifrices containing strontium acetate/sodium fluoride (SrAc2F) and potassium chloride/sodium monofluorophosphate (KCl/MFP) in alleviating discomfort arising from cervical dentine sensitivity (CDS). The aim of this investigation, therefore, was to determine efficacy of a SrAc2F dentifrice compared with KCl/MFP and a commercially available fluoride dentifrice containing sodium fluoride/sodium monofluorophosphate (NaMFP). Fifty-six patients participated in a 2-center double-blind, 3-way comparative parallel 6-week clinical study. Patients were evaluated at 0, 2, and 6 weeks for tactile (Yeaple probe), air sensitivity (dental air syringe), and subjective perception of pain (VAS scores). Results for Yeaple probe scores (Wilcoxon tests) between 2 weeks and baseline were highly significant for KCl/MFP, significant for NaMFP and nonsignificant for SrAc2F; scores between 6 weeks and baseline were, however, highly significant for all groups. Subjective Yeaple probe VAS scores (paired t-tests) between 6 weeks and baseline were significant for all groups; significance was demonstrated in the KCl/MFP group between 2 weeks and baseline. Subjective air visual analogue scores (paired t-tests) between 2 weeks and baseline were highly significant for all groups. There were no significant differences between groups at any time point. The results of the study demonstrated that the commercially available fluoride-containing dentifrice was as effective as the 2 desensitizing dentifrices in alleviating CDS over time.