Axin1's mystique in manipulating microbiome amidst colitis

Classically, Axin1 is considered a regulator of Wnt/β-catenin signaling. However, Axin1's roles in host-microbial interactions have been unknown. Our recent study has demonstrated that deletion of intestinal epithelial Axin1 in epithelial cells and Paneth cells protects the host against colitis by enhancing Akkermansia muciniphila. Loss of intestinal epithelial or Paneth cell Axin1 results in increased Wnt/β-catenin signaling, proliferation, and cell migration. This is associated with morphologically altered goblet and Paneth cells, including increased Muc2 and decreased lysozyme. Axin1 deletion specifically enriched Akkermansia muciniphila. Akkermansia muciniphila in Axin1 knockout mice is the driver of protection against DSS-induced inflammation. Here, we feature several significant conceptual changes, such as differences between Axin1 and Axin2, Axin1 in innate immunity and microbial homeostasis, and Axin1 reduction of Akkermansia muciniphila. We discuss an important trend in the field related to Paneth cells and tissue-specific Axin1 manipulation of microbiome in health and inflammation.

Intestinal vitamin D receptor protects against extraintestinal breast cancer tumorigenesis

The microbiota plays critical roles in regulating the function and health of the intestine and extraintestinal organs. A fundamental question is whether an intestinal-microbiome-breast axis exists during the development of breast cancer. If so, what are the roles of host factors? Vitamin D receptor (VDR) involves host factors and the human microbiome. Vdr gene variation shapes the human microbiome, and VDR deficiency leads to dysbiosis. We hypothesized that intestinal VDR protects hosts against tumorigenesis in the breast. We examined a 7,12-dimethylbenzanthracene (DMBA)-induced breast cancer model in intestinal epithelial VDR knockout (VDRΔIEC) mice with dysbiosis. We reported that VDRΔIEC mice with dysbiosis are more susceptible to breast cancer induced by DMBA. Intestinal and breast microbiota analysis showed that VDR deficiency leads to a bacterial profile shift from normal to susceptible to carcinogenesis. We found enhanced bacterial staining within breast tumors. At the molecular and cellular levels, we identified the mechanisms by which intestinal epithelial VDR deficiency led to increased gut permeability, disrupted tight junctions, microbial translocation, and enhanced inflammation, thus increasing tumor size and number in the breast. Furthermore, treatment with the beneficial bacterial metabolite butyrate or the probiotic Lactobacillus plantarum reduced breast tumors, enhanced tight junctions, inhibited inflammation, increased butyryl-CoA transferase, and decreased levels of breast Streptococcus bacteria in VDRΔIEC mice. The gut microbiome contributes to the pathogenesis of diseases not only in the intestine but also in the breast. Our study provides insights into the mechanism by which intestinal VDR dysfunction and gut dysbiosis lead to a high risk of extraintestinal tumorigenesis. Gut-tumor-microbiome interactions represent a new target in the prevention and treatment of breast cancer.

Vitamin D receptor upregulates tight junction protein claudin-5 against colitis-associated tumorigenesis

Tight junctions are essential for barrier integrity, inflammation, and cancer. Vitamin D and the vitamin D receptor (VDR) play important roles in colorectal cancer (CRC). Using the human CRC database, we found colonic VDR expression was low and significantly correlated with a reduction of Claudin-5 mRNA and protein. In the colon of VDR^ΔIEC mice, deletion of intestinal VDR led to lower protein and mRNA levels of Claudin-5. Intestinal permeability was increased in the VDR^-/- colon cancer model. Lacking VDR and a reduction of Claudin-5 are associated with an increased number of tumors in the VDR^-/- and VDR^ΔIEC mice. Furthermore, gain and loss functional studies have identified CLDN-5 as a downstream target of VDR. We identified the Vitamin D response element (VDRE) binding sites in a reporter system showed that VDRE in the Claudin-5 promoter is required for vitamin D₃-induced Claudin-5 expression. Conditional epithelial VDR overexpression protected against the loss of Claudin-5 in response to inflammation and tumorigenesis in vivo. We also reported fecal VDR reduction in a colon cancer model. This study advances the understanding of how VDR regulates intestinal barrier functions in tumorigenesis and the possibility for identifying new biomarker and therapeutic targets to restore VDR-dependent functions in CRC.

Gastrointestinal symptoms, pathophysiology, and treatment in COVID-19

The novel coronavirus Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has emerged and is responsible for the Coronavirus Disease 2019 global pandemic. Coronaviruses, including SARS-CoV-2, are strongly associated with respiratory symptoms during infection, but gastrointestinal symptoms, such as diarrhea, vomiting, nausea, and abdominal pain, have been identified in subsets of COVID-19 patients. This article focuses on gastrointestinal symptoms and pathophysiology in COVID-19 disease. Evidence suggests that the gastrointestinal tract could be a viral target for SARS-CoV-2 infection. Not only is the SARS-CoV-2 receptor ACE2 highly expressed in the GI tract and is associated with digestive symptoms, but bleeding and inflammation are observed in the intestine of COVID-19 patients. We further systemically summarize the correlation between COVID-19 disease, gastrointestinal symptoms and intestinal microbiota. The potential oral-fecal transmission of COVID-19 was supported by viral RNA and live virus detection in the feces of COVID-19 patients. Additionally, the viral balance in the GI tract could be disordered during SARS-CoV-2 infection which could further impact the homeostasis of the gut microbial flora. Finally, we discuss the clinical and ongoing trials of treatments/therapies, including antiviral drugs, plasma transfusion and immunoglobulins, and diet supplementations for COVID-19. By reviewing the pathogenesis of SARS-CoV-2 virus, and understanding the correlation among COVID-19, inflammation, intestinal microbiota, and lung microbiota, we provide perspective in prevention and control, as well as diagnosis and treatment of the COVID-19 disease.

Hearing Evaluation of ARthroplasty Surgeons: results from the HEARS study

AIMS

The aim of this study was to investigate whether the prevalence of hearing loss among arthroplasty surgeons was comparable to clinicians from other medical specialties and to explore the factors associated with hearing loss.

METHODS

A cross-sectional prevalence study was carried out. Arthroplasty surgeons and non-surgical clinicians were recruited from orthopaedic and medical conferences. All participants were given a paper questionnaire including demographic details, hearing history and the Tinnitus and Hearing Survey. All participants were screened for hearing loss in a quiet room using the HearCheck Screener^™ (HCS; Siemens, Munich, Germany). Logistic regression was used to identify factors associated with hearing loss. All statistical models were adjusted for age, gender, smoking status and personal noise exposure.

RESULTS

The HEARS (Hearing Evaluation of ARthroplasty Surgeons) study recruited 188 participants (106 arthroplasty surgeons; 82 non-surgical clinicians). Prevalence of hearing loss identified by the HCS was 31% for arthroplasty surgeons vs 11% for non-surgical clinicians. The odds of failing the HCS were 3.7 times higher in arthroplasty surgeons compared to their non-surgical colleagues (p < 0.004). The odds of self-reported hearing using the Tinnitus and Hearing Survey were 2.79 times higher among arthroplasty surgeons (p < 0.003).

CONCLUSION

The prevalence of hearing loss among arthroplasty surgeons is significantly higher than in their non-surgical colleagues. Noise generated during arthroplasty surgery should be recognised and managed to create safer working conditions.

Aberrant enteric neuromuscular system and dysbiosis in amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis is a neuromuscular disease characterized by the progressive death of motor neurons and muscle atrophy. The gastrointestinal symptoms in ALS patients were largely ignored or underestimated. The relationship between the enteric neuromuscular system and microbiome in ALS progression is unknown. We performed longitudinal studies on the enteric neuron system (ENS) and microbiome in the ALS human-SOD1G93A (Superoxide Dismutase 1) transgenic mice. We treated age-matched wild-type and ALS mice with butyrate or antibiotics to investigate the microbiome and neuromuscular functions. We examined intestinal mobility, microbiome, an ENS marker GFAP (Glial Fibrillary Acidic Protein), a smooth muscle marker (SMMHC, Smooth Muscle Myosin Heavy Chain), and human colonoids. The distribution of human-G93A-SOD1 protein was tested as an indicator of ALS progression. At 2-month-old before ALS onset, SOD1G93A mice had significantly lower intestinal mobility, decreased grip strength, and reduced time in the rotarod. We observed increased GFAP and decreased SMMHC expression. These changes correlated with consistent increased aggregation of mutated SOD1G93A in the colon, small intestine, and spinal cord. Butyrate or antibiotics treated SOD1G93A mice had a significantly longer latency to fall in the rotarod test, reduced SOD1G93A aggregation, and enhanced enteric neuromuscular function. Feces from 2-month-old SOD1G93A mice significantly enhanced SOD1G93A aggregation in human colonoids transfected with a SOD1G93A-GFP plasmid. Longitudinal studies of microbiome data further showed the altered bacterial community related to autoimmunity (e.g., Clostridium sp. ASF502, Lachnospiraceae bacterium A4), inflammation (e.g., Enterohabdus Muris,), and metabolism (e.g., Desulfovibrio fairfieldensis) at 1- and 2-month-old SOD1G93A mice, suggesting the early microbial contribution to the pathological changes. We have demonstrated a novel link between the microbiome, hSOD1G93A aggregation, and intestinal mobility. Dysbiosis occurred at the early stage of the ALS mice before observed mutated-SOD1 aggregation and dysfunction of ENS. Manipulating the microbiome improves the muscle performance of SOD1G93A mice. We provide insights into the fundamentals of intestinal neuromuscular function and microbiome in ALS.

Lactic Acid Bacteria Isolated From Korean Kimchi Activate the Vitamin D Receptor-autophagy Signaling Pathways

BACKGROUND

Probiotic lactic acid bacteria (LAB) have been used in the anti-inflammation and anti-infection process of various diseases, including inflammatory bowel disease (IBD). Vitamin D receptor (VDR) plays an essential role in pathogenesis of IBD and infectious diseases. Previous studies have demonstrated that the human VDR gene is a key host factor to shape gut microbiome. Furthermore, intestinal epithelial VDR conditional knockout (VDRΔIEC) leads to dysbiosis. Low expressions of VDR is associated with impaired autophagy, accompanied by a reduction of ATG16L1 and LC3B. The purpose of this study is to investigate probiotic effects and mechanism in modulating the VDR-autophagy pathways.

METHODS

Five LAB strains were isolated from Korean kimchi. Conditional medium (CM) from these strains was used to treat a human cell line HCT116 or intestinal organoids to measure the expression of VDR and autophagy. Mouse embryonic fibroblast (MEF) cells with or without VDR were used to investigate the dependence on the VDR signaling. To test the role of LAB in anti-inflammation, VDR+/+ organoids were treated with 121-CM before infection with Salmonella enterica serovar Enteritidis. In vivo, the role of LAB in regulating VDR-autophagy signaling was examined using LAB 121-CM orally administrated to VDRLoxp and VDRΔIEC mice.

RESULTS

The LAB-CM-treated groups showed higher mRNA expression of VDR and its target genes cathelicidin compared with the control group. LAB treatment also enhanced expressions of Beclin-1 and ATG16L1 and changed the ratio of LC3B I and II, indicating the activation of autophagic responses. Furthermore, 121-CM treatment before Salmonella enterica serovar Enteritidis infection dramatically increased VDR and ATG16L1 and inhibited the inflammation. Administration of 121-CM to VDRLoxp and VDRΔIEC mice for 12 and 24 hours resulted in an increase of VDR and LC3B II:I ratio. Furthermore, we identified that probiotic proteins P40 and P75 in the LAB-CM contributed to the anti-inflammatory function by increasing VDR.

CONCLUSIONS

Probiotic LAB exert anti-inflammation activity and induces autophagy. These effects depend on the VDR expression. Our data highlight the beneficial effects of these 5 LAB strains isolated from food in anti-infection and anti-inflammation.

Determination of Percentage of RoundUp Ready® Soya in Soya Flour Using Real-Time Polymerase Chain Reaction: Interlaboratory Study

An interlaboratory study was conducted to evaluate a method for determination of the percentage of RoundUp Ready® (RR) soya in soya flour using Taqman® technology. The method included DNA extraction from the test portion with cetyltrimethylammonium bromide buffer followed by chloroform extraction and Wizard® resin cleanup steps. The DNA was then assayed with primer and probe sets specific for lectin as the endogenous control and the RR insert as the target. The percentage of RR soya in the soya fraction of the sample was calculated by using a matrix-matched standard curve. Ten samples of split-level blind duplicates were sent to 22 laboratories in 12 countries worldwide. Test portions contained 0, 0.5, 0.7, 1.6, 2, and 3.9% (w/w) RR soya prepared gravimetrically from commercially available RR standard reference materials. Based on the results for test materials, the relative standard deviation for repeatability (RSDr) for the method ranged from 9.3 to 19.3% and, for reproducibility (RSDR), ranged from 20.3 to 33.7%.

Validation of an Immunoassay for Detection and Quantitation of a Genetically Modified Soybean in Food and Food Fractions Using Reference Materials: Interlaboratory Study

An immunoassay for detection of a specific genetically modified soybean (Roundup-Ready®) was validated on dried soybean powder in an interlaboratory study. Different percentages of genetically modified soybeans in nonmodified soybean matrix were evaluated in a blind study. Thirty-eight laboratories from 13 countries participated. The immunoassay was evaluated for 2 endpoints: (1) To give a semiquantitative result, i.e., determination of a given sample above or below a given threshold, or (2) to compute a quantitative result, i.e., percentage of genetically modified soybeans in the sample. Semiquantitative results showed that a given sample which contained &lt;2% genetically modified soybeans was identified as below 2% with a 99% confidence level. Quantitative use of the assay resulted in a repeatability (r) and reproducibility (R) that were computed to be RSDr = 7% and RSDR = 10%, respectively, for a sample containing 2% genetically modified soybeans. Application of this method depends on availability of appropriate reference materials for a specific food matrix. Only matrix-matched reference materials can be used for analysis of food or food fractions.

Salmonella Infection in Chronic Inflammation and Gastrointestinal Cancer

Salmonella not only causes acute infections, but can also cause patients to become chronic "asymptomatic" carriers. Salmonella has been verified as a pathogenic factor that contributes to chronic inflammation and carcinogenesis. This review summarizes the acute and chronic Salmonella infection and describes the current research progress of Salmonella infection contributing to inflammatory bowel disease and cancer. Furthermore, this review explores the underlying biological mechanism of the host signaling pathways manipulated by Salmonella effector molecules. Using experimental animal models, researchers have shown that Salmonella infection is related to host biological processes, such as host cell transformation, stem cell maintenance, and changes of the gut microbiota (dysbiosis). Finally, this review discusses the current challenges and future directions in studying Salmonella infection and its association with human diseases.

New Zealand general practice nurses' roles in mental health care

AIM

To examine the roles of nurses in general practice interdisciplinary teams caring for people with mild to moderate mental health conditions.

BACKGROUND

Supporting mental health and well-being is an important aspect of primary care. Until now nurses in general practice settings have had variable roles in providing mental health care. The New Zealand Primary Mental Health Initiatives are 26 government-funded, time-limited projects using different service delivery models.

METHODS

An analysis was undertaken of a qualitative data set of interviews, which included commentary about nurses mental health work collected from the different project stakeholders throughout a 29-month external evaluation.

FINDINGS

Two main groups of roles for nurses within the general practice interdisciplinary team were identified: specialist mental health nurses working in newly created roles and practice nurses working in existing roles. Barriers exist to the development of the latter roles.

CONCLUSIONS

Mental health care is a key role in general practice as this is where people frequently present. Internationally, nurses represent a large workforce with the potential to provide effective mental health care. This study found that attitudinal, structural and professional barriers are restricting New Zealand practice nurse role development in the care of those with mild to moderate mental health conditions. There is potential to develop their role within a structured pathway by workforce development and recognition of the value of interdisciplinary care. Given the shortage of mental health professionals this will be an important aspect of the improvement of primary mental health care.

The drug delivery and biomaterial attributes of the ATRIGEL®technology in the treatment of periodontal disease

Two new products, ATRIDOX Periodontal Treatment and ATRISORB Guided Tissue Regeneration (GTR) Barrier have been evaluated as therapies for periodontal disease. Both products are based on the unique ATRIGEL technology. The system consists of a solution of a resorbable polymer in a biocompatible carrier. On in vivo administration, the polymer undergoes a phase change from a liquid to an in situ formed implant. Being in liquid form, it initially provides the advantage of in vivo placement by simple means, such as syringes to form implants at the site of use. The system is biocompatible and has the capability of serving as a biomaterial and a drug delivery system. The bioabsorption rates of various polymers and the release rates for a wide variety of drugs ranging from simple organics to proteins and peptides are tailored to the desired indication. Release periods ranging from one week to four months have been achieved with one month being the most often desired. For these reasons the ATRIGEL system is being applied to a number of medical applications ranging from site and systemic oncology to post-operative pain control and bone regeneration using growth factors. However, its most visible application to date has been in the development of a pipeline of products for the treatment of periodontal disease, which is the focus of this paper.

The significance of prior mechanical therapy for changes of periodontal status achieved by local delivery of a doxycyclinehyclate containing gel

AIM

The purpose of this retrospective analysis was to examine what effect, if any, the time elapsed between an individual's last episode of scaling and root planing and subsequent treatment with a sustained-release doxycycline hyclate gel (DH) alone or scaling and root planing alone (SRP) would have upon adult periodontitis.

METHODS

A total of 207 subjects were included in the DH group and 210 patients in the SRP group. Periodontitis was defined as those sites which presented with pocket depths > or =5 mm and exhibited bleeding upon probing. In both DH and SRP groups, 3 sub-groups of subjects were identified according to their last episode of scaling and root planing prior to the study baseline: within 2 to 6 months, >6 but < or =12 months, and one or more times in their life but not within the last 12 months. Each study site was treated twice over a 9-month study period, once at baseline and again at 4 months. Data from the study sites at 4, 6, and 9 months were then evaluated for changes in probing depth, clinical attachment level, and bleeding upon probing.

RESULTS

At the 9-month evaluation, all sub-groups in the DH and SRP treatment arms presented with improvement in the measured clinical parameters, as compared to baseline. No significant differences were observed in the measured periodontal indices among the study sites between the three sub-groups for either treatment.

CONCLUSIONS

It is concluded that the time interval since the last episode of scaling and root planing had no observable effect on the results achieved when treating periodontitis sites with locally delivered doxycycline hyclate alone or scaling and root planing alone. The treatment of periodontitis sites with locally delivered doxycycline hyclate resulted in clinical improvement comparable to scaling and root planing irrespective of the patient's prophylaxis frequency.

Utilisation of locally delivered doxycycline in non-surgical treatment of chronic periodontitis. A comparative multi-centre trial of 2 treatment approaches

AIM

In the present 6-month multicentre trial, the outcome of 2 different approaches to non-surgical treatment of chronic periodontitis, both involving the use of a locally delivered controlled-release doxycycline, was evaluated.

MATERIAL AND METHODS

105 adult patients with moderately advanced chronic periodontitis from 3 centres participated in the trial. Each patient had to present with at least 8 periodontal sites in 2 jaw quadrants with a probing pocket depth (PPD) of > or =5 mm and bleeding following pocket probing (BoP), out of which at least 2 sites had to be > or =7 mm and a further 2 sites > or =6 mm. Following a baseline examination, including assessments of plaque, PPD, clinical attachment level (CAL) and BoP, careful instruction in oral hygiene was given. The patients were then randomly assigned to one of two treatment groups: scaling/root planing (SRP) with local analgesia or debridement (supra- and subgingival ultrasonic instrumentation without analgesia). The "SRP" group received a single episode of full-mouth supra-/subgingival scaling and root planing under local analgesia. In addition, at a 3-month recall visit, a full-mouth supra-/subgingival debridement using ultrasonic instrumentation was provided. This was followed by subgingival application of an 8.5% w/w doxycycline polymer at sites with a remaining PPD of > or =5 mm. The patients of the "debridement" group were initially subjected to a 45-minute full-mouth debridement with the use of an ultrasonic instrument and without administration of local analgesia, and followed by application of doxycycline in sites with a PPD of > or =5 mm. At month 3, sites with a remaining PPD of > or =5 mm were subjected to scaling and root planing. Clinical re-examinations were performed at 3 and 6 months.

RESULTS

At 3 months, the proportion of sites showing PPD of < or =4 mm was significantly higher in the "debridement" group than in the "SRP" group (58% versus 50%; p<0.05). The CAL gain at 3 months amounted to 0.8 mm in the "debridement" group and 0.5 mm in the "SRP" group (p=0.064). The proportion of sites demonstrating a clinically significant CAL gain (> or =2 mm) was higher in the "debridement" group than in the "SRP" group (38% versus 30%; p<0.05). At the 6-month examination, no statistically significant differences in PPD or CAL were found between the two treatment groups. BoP was significantly lower for the "debridement" group than for the "SRP" group (p<0.001) both at 3- and 6 months. The mean total treatment time (baseline and 3-month) for the "SRP" patients was 3:11 h, compared to 2:00 h for the patients in the "debridement" group (p<0.001).

CONCLUSION

The results indicate that simplified subgingival instrumentation combined with local application of doxycycline in deep periodontal sites can be considered as a justified approach for non-surgical treatment of chronic periodontitis.

Periodontal regeneration of a class II furcation defect utilizing a bioabsorbable barrier in a human. A case study with histology

This case report describes human histologic data of periodontal regeneration following guided tissue regeneration therapy (GTR) with a bioabsorbable barrier composed of polylactic acid. The tooth that was examined was part of a previously published study of the clinical effects of GTR therapy without the use of bone or bone substitutes on Class II furcation defects. Twenty-five months following the surgical procedure, the tooth was extracted for non-periodontal reasons. During this extraction, the bone within the furcation that was treated in the study was luxated with the tooth. At the completion of the study (month 12), the furcation's vertical probing depth had decreased by 2 mm with a 2 mm gain in clinical attachment. The horizontal furcation measurement decreased by 3 mm. Following extraction, the tooth was prepared for light microscopy and sectioned in the mesial-distal plane. Reference notches were not placed in the tooth at the time of surgery as there were no plans to perform histologic analysis in the study. However, using the buccal root prominences and what we interpreted to be root planing marks on the cementum, we were able to demonstrate that complete periodontal regeneration occurred on the root surface that was exposed to the pocket environment prior to surgery. New alveolar bone, cementum, and periodontal ligament were consistently observed throughout the furcation in the areas that demonstrated clinical attachment gain and a decrease in horizontal probing depth. This case report adds to the accumulating evidence of histologic periodontal regeneration following guided tissue regeneration with bioabsorbable polylactic acid barriers.

Field gleaning as a tool for addressing food security at the local level: case study

Field gleaning, or harvesting crops after the commercial harvest, has been promoted as a way to increase food security; however, the effectiveness of gleaning programs is not well documented. The purpose of this research was to explore the impact of gleaning on individual gleaners and the community by documenting total amounts gleaned, individual uses of produce, and self-reported benefits and barriers to gleaning. During the 1997 season, approximately 50 gleaners participated in the Pierce County Expanded Food and Nutrition Education Program Gleaning Project; 29 participated in an intensive 4-week study to track use of produce by gleaners. Onsite weighing of gleaned produce revealed that of the 110,000 pounds gleaned by these 50 gleaners from Pierce County farms and orchards during 1997, 85,000 pounds (77%) were donated to local emergency food programs; 25,000 pounds (23%) were taken home by gleaners. Of the produce taken home by the 29 study participants, an estimated 9% was used fresh, 48% was preserved for later user, and 43% was shared with others. During a combination of telephone and in-person interviews, gleaners reported using more fresh produce and sharing knowledge about gardening and food preservation. The most important benefits of gleaning were "stretching my food budget" and "helping provide food for the community." Detailed exploration of the impact of gleaned produce on dietary patterns and use of validated food security measures is warranted considering the volume of produce used fresh, preserved for later use, and given away by gleaning participants.

Reciprocal activation by cyclin-dependent kinases 2 and 7 is directed by substrate specificity determinants outside the T loop

Cyclin-dependent kinase 7 (CDK7) is the catalytic subunit of the metazoan CDK-activating kinase (CAK), which activates CDKs, such as CDC2 and CDK2, through phosphorylation of a conserved threonine residue in the T loop. Full activation of CDK7 requires association with a positive regulatory subunit, cyclin H, and phosphorylation of a conserved threonine residue at position 170 in its own T loop. We show that threonine-170 of CDK7 is phosphorylated in vitro by its targets, CDC2 and CDK2, which also phosphorylate serine-164 in the CDK7 T loop, a site that perfectly matches their consensus phosphorylation site. In contrast, neither CDK4 nor CDK7 itself can phosphorylate the CDK7 T loop in vitro. The ability of CDC2 or CDK2 and CDK7 to phosphorylate each other but not themselves implies that each kinase can discriminate among closely related sequences and can recognize a substrate site that diverges from its usual preferred site. To understand the basis for this paradoxical substrate specificity, we constructed a chimeric CDK with the T loop of CDK7 grafted onto the body of CDK2. Surprisingly, the hybrid enzyme, CDK2-7, was efficiently activated in cyclin A-dependent fashion by CDK7 but not at all by CDK2. CDK2-7, moreover, phosphorylated wild-type CDK7 but not CDK2. Our results suggest that the primary amino acid sequence of the T loop plays only a minor role, if any, in determining the specificity of cyclin-dependent CAKs for their CDK substrates and that protein-protein interactions involving sequences outside the T loop can influence substrate specificity both positively and negatively.

Preliminary in vivo studies on the osteogenic potential of bone morphogenetic proteins delivered from an absorbable puttylike polymer matrix

This article describes preliminary in vivo studies evaluating the osteogeneic potential of bone morphogenetic proteins (BMPs) delivered from an absorbable puttylike polymer matrix. In the first study, bovine-derived bone morphogenetic proteins were incorporated in an polymer matrix consisting of 50:50 poly(DL-lactide-co-glycolide) dissolved in N-methyl-2-pyrrolidone. The matrix was implanted in an 8 mm critical-size calvarial defect created in the skull of adult Sprague-Dawley rats (n = 5 per treatment group). After 28 days, the implant sites were removed and examined for new bone formation, polymer degradation, and tissue reaction. Gamma-irradiated polymer matrices appeared to give more bone formation than nonirradiated samples (histological analysis; 2. 76 + 1.34 mm(2) of bone versus 1.30 + 0.90 mm(2) of bone, respectively and x-ray analysis; 27.2 + 15.9 mm(2) of bone versus 20. 7 + 16.7 mm(2) of bone, respectively) and less residual polymer (0.0 + 0.0 versus 0.2 + 0.4, respectively). The polymer implants with bone morphogenetic protein also gave less inflammatory response than the polymer controls (gamma irradiated polymer/BMP = 1.8 + 0.4 and nonirradiated polymer/BMP = 1.2 + 0.4 versus polymer only = 3.0 + 1. 2, respectively). However, despite trends in both the x-ray and histological data there was no statistical difference in the amount of new bone formed among the four treatment groups (P > 0.05). This was most likely due to the large variance in the data scatter and the small number of animals per group. In the second animal study, bovine-derived BMPs and the polymeric carrier were gamma irradiated separately, at doses of 1.5 or 2.5 Mrad, and their ability to form bone in a rat skull onlay model was evaluated using Sprague-Dawley rats (n = 5 per treatment group). Histomorphometry of skull caps harvested 28 days after implantation showed no significant differences as compared to non-irradiated samples, in implant area, new bone area, and percent new bone (P > 0.05). These results suggest gamma irradiation may be useful in sterilization of the bovine-derived BMPs and the polymeric carrier for potential bone repair and/or regeneration applications.

The effects of sustained release doxycycline on the anaerobic flora and antibiotic-resistant patterns in subgingival plaque and saliva

BACKGROUND

The purpose of this study was to determine the effects of periodontal treatment with a sustained-release, biodegradable gel containing 8.5% doxycycline on the anaerobic flora and on antibiotic susceptibility patterns associated with subgingival plaque and saliva.

METHODS

Forty-five subjects with adult periodontitis were entered into a parallel design, single-blind study of 6 months' duration. The subjects were randomized to receive either doxycycline treatment (n = 23) or oral hygiene instruction/reinforcement (n = 22). Saliva and subgingival plaque samples were collected prior to and at 7, 21, 91, and 182 days after initiation of treatment. The proportion of the cultivable flora resistant to 10 microg doxycycline/ml was determined relative to total anaerobic counts, and the 3 most predominant colony types resistant to doxycycline were individually enumerated. A representative of each was subcultured, identified to genus and species level, and tested for its susceptibilities to 6 antibiotics.

RESULTS

A significant decrease (P <0.01) in total anaerobic counts following doxycycline treatment caused a transient increase in the proportion, but not in the actual counts, of doxycycline-resistant bacteria recovered from both plaque and saliva at 7 and 21 days but not at 91 or 182 days. The same doxycycline-resistant taxa were recovered at all sample periods including baseline. Regardless of treatment, the isolates were similarly distributed and belonged to the same bacterial groups.

CONCLUSIONS

Doxycycline treatment significantly reduced the anaerobic population in plaque but did not result in a change in either the number of resistant bacteria present or the acquisition of antibiotic resistance.

The effect of locally delivered controlled-release doxycycline or scaling and root planing on periodontal maintenance patients over 9 months

BACKGROUND

This research report evaluates clinical changes resulting from local delivery of doxycycline hyclate (DH) or traditional scaling and root planing (SRP) in a group of patients undergoing supportive periodontal therapy (SPT).

METHODS

In all, 141 patients received either DH (67) or SRP (74) treatment in sites > or =5 mm on one-half of their dentition at baseline and month 4.

RESULTS

Clinical results were determined at month 9. Baseline mean probing depth recordings were similar between the two groups (DH = 5.9 mm; SRP = 5.9 mm). Mean month 9 results showed similar clinical results for attachment level gain (DH 0.7 mm; SRP 0.8 mm) and probing depth reduction (DH 1.3 mm; SRP 1.1 mm). Percentage of sites showing > or =2 mm attachment level gain at month 9 was 24.7% in the DH group and 21.2% in the SRP group. Thirty-nine percent (39%) of DH sites and 38% of SRP sites showed > or =2 mm probing depth reduction. When treated sides of the dentition were compared to untreated sides, DH showed a difference in disease activity (> or =2 mm attachment loss) from 19.3% (untreated) to 7.2% (treated); and SRP from 14.3% (untreated) to 8.1% (treated).

CONCLUSIONS

Results show that both DH without concomitant mechanical instrumentation and SRP were equally effective as SPT in this patient group over the 9-month study period.

Evidence-based medicine and cost-effectiveness

Most available medical management techniques compare the practice patterns of providers with other providers but overlook the inherent value of interventional medical therapies to patients and society. The authors present a methodology for objectively evaluating the quality and cost-effectiveness of medical interventional therapies, and comparing them to each other using the common denominator of cost per quality-adjusted life-year ($/QALY). Advantages of this methodology include the fact that it: (1) compares the cost-effectiveness of different treatment regimens, (2) incorporates patient preferences, (3) employs evidenced-based medical data, information that is most reliable and reproducible, (4) factors in the effect of treatment on the quality of life and length of life, (5) offers an evaluation of the clinical efficacy of a treatment, (6) identifies both superior and marginal treatments, (7) maximizes the effective use of scarce resources, and (8) simplifies the understanding of health care procedures for consumers, payers, and providers.

Effects of smoking on local delivery of controlled-release doxycycline as compared to scaling and root planing

This paper examines the effects of smoking on the treatment outcomes of two nonsurgical therapies: (1) scaling and root planing alone (SRP) or (2) controlled-release of subgingivally delivered doxycycline hyclate in a polylactic acid based polymer gel. Subjects from 2 9-month multicenter studies were classified as nonsmokers (never smoked: 100 subjects), former smokers (137 subjects), and current smokers (> or = 10 cigarettes/day: 121 subjects). Clinical parameters were analyzed for treated sites with baseline probing depths > or = 5 mm and for a subset of treated sites with baseline probing depths of > or = 7 mm. Clinical parameters (plaque levels, clinical attachment levels, pocket depths, and bleeding on probing) were analyzed at baseline, 4, 6, and 9 months. In the doxycycline treated group in general, there were neither marked significant differences in clinical attachment gain nor differences in probing depth reduction among the 3 smoking groups. On the other hand, in the scaling and root planing treated group in general, there were significant differences in clinical attachment gain and pocket depth reduction, with non-smokers responding better than former smokers and current smokers at 6 and 9 months. These differences in clinical response between scaling and root planing alone versus controlled-release of locally-delivered doxycycline hyclate among these 3 smoking groups are discussed in relation to treatment implications for smokers.

Evaluation of bone-implant integration: efficiency and precision of 3 methods

Computer-assisted planimetry, computer-assisted lineal analysis, and point-counting stereology have been compared with respect to their reproducibility and the time required to analyze bone-implant integration. Sections of 6 threaded dental implants selected from a bone augmentation experiment for their wide range of new bone formation were analyzed by each method 3 times. The bone density and percentage of osseous integration were evaluated at 4 sites around each implant section. It was found that computer-assisted planimetry demonstrated a modest but significantly greater variance (P < .05) in bone density estimates when compared to the computer-assisted lineal analysis and point-counting methods. Computer-assisted planimetry requires a different method of measuring each parameter and separate fields of view to evaluate fields distant from the implant. However, this can all be accomplished with line probes, as in computer-assisted lineal analysis, which extend from the implant surface into the surrounding alveolar bone. Whereas computer-assisted planimetry requires a separate identification of the perimeter of each field to be analyzed (next to and distant from the implant), computer-assisted lineal analysis allows expansion of the field to be evaluated without creating a new field of view. Also, following a limited learning curve, both point-counting and computer-assisted lineal analysis required less time to complete than did computer-assisted planimetry.

Evidence-based medicine, utilities, and quality of life

Evidence-based medicine provides the highest quality of information for medical practitioners. At the top of the pyramid of evidence-based medicine are the prospective, randomized clinical trials and meta-analysis. Evidence-based medicine can be incorporated with quality-of-life parameters; the latter can be quantified using utility theory. With utility theory, utility values range from 0.0 (death state) to 1.0 (perfect health state). The higher the utility value, the better a person's quality of life. Interventional treatment can change the utility level experienced by a patient. A change in utility value induced by an interventional treatment can be amalgamated with the duration of the treatment effect to provide the number of quality-adjusted life-years (QALYs) gained by a specific treatment (QALYs = [gain in utility value] x [duration of treatment effect]). Thus, this formula takes into account both the improvement in quality of life and the improvement in length of life gained by a treatment. The number of QALYs gained by a treatment can then be incorporated with medical costs (discounted for the time value of money) to arrive at a final common denominator of $/QALY (cost per QALY). The parameter $/QALY can be used to compare the cost-effectiveness of interventional treatments across diverse specialties in medicine. In essence, this methodology allows a measure of the cost-effectiveness of a treatment that incorporates the highest quality of scientific information, clinical efficacy, patient quality-of-life preferences, and realistic costs.

Two multi-center studies evaluating locally delivered doxycycline hyclate, placebo control, oral hygiene, and scaling and root planing in the treatment of periodontitis

BACKGROUND

The clinical efficacy and safety of doxycycline hyclate (8.5% w/w) delivered subgingivally in a biodegradable polymer (DH) was compared to placebo control (VC), oral hygiene (OH), and scaling and root planing (SRP) in 2 multi-center studies.

METHODS

Each study entered 411 patients who demonstrated moderate to severe periodontitis. Patients had 2 or more quadrants each with a minimum of 4 qualifying pockets > or =5 mm that bled on probing. At least 2 of the pockets were > or =7 mm. Treatment with DH, VC, OH, or SRP was provided at baseline and again at month 4. Clinical parameters were recorded monthly.

RESULTS

DH and SRP resulted in nearly identical clinical changes over time in both studies. Mean 9 month clinical attachment level gain (ALG) was 0.8 mm for the DH group and 0.7 mm for the SRP group in Study 1, and 0.8 mm (DH) and 0.9 mm (SRP) in Study 2. Mean probing depth (PD) reduction was 1.1 mm for the DH group and 0.9 mm for the SRP group in Study 1 and 1.3 mm for both groups in Study 2. Frequency distributions showed an ALG > or =2 mm in 29% of DH sites versus 27% of SRP sites in Study 1 and 31% of DH sites versus 34% of SRP sites in Study 2. PD reductions > or =2 mm were seen in 32% of DH sites versus 31% of SRP sites in Study 1 and 41% of DH sites versus 43% of SRP sites in Study 2. Comparisons between DH, VC, and OH treatment groups showed DH treatment to be statistically superior to VC and OH. Safety data demonstrated a benign safety profile with use of the DH product.

CONCLUSIONS

Results of this trial demonstrate that treatment of periodontitis with subgingivally delivered doxycycline in a biodegradable polymer is equally effective as scaling and root planing and superior in effect to placebo control and oral hygiene in reducing the clinical signs of adult periodontitis over a 9-month period. This represents positive changes resulting from the use of subgingivally applied doxycycline as scaling and root planing was not limited regarding time of the procedure or use of local anesthesia.

Local delivery of doxycycline for the treatment of periodontitis

The use of local drug delivery to treat periodontitis is effective in various clinical circumstances. This article describes clinical results after using locally delivered doxycycline to treat periodontitis and compares those results to scaling and root planing. Commonly asked questions concerning the use of local doxycycline treatment are also discussed.

GATA4 haploinsufficiency in patients with interstitial deletion of chromosome region 8p23.1 and congenital heart disease

Previous studies have shown that patients with deletion of distal human chromosome arm 8p may have congenital heart disease and other physical anomalies. The gene encoding GATA-4, a zinc finger transcription factor implicated in cardiac gene expression and development, localizes to chromosome region 8p23.1. To examine whether GATA-4 deficiency is present in patients with monosomy of 8p23.1 with congenital heart disease, we performed fluorescence in situ hybridization (FISH) with a GATA4 probe on cells from a series of patients with interstitial deletion of 8p23.1. Four individuals with del(8)(p23.1) and congenital heart disease were found to be haploinsufficient at the GATA4 locus by FISH. The GATA4 gene was not deleted in a fifth patient with del(8)(p23.1) who lacked cardiac anomalies. FISH analysis on cells from 48 individuals with congenital heart disease and normal karyotypes failed to detect any submicroscopic deletions at the GATA4 locus. We conclude that haploinsufficiency at the GATA4 locus is often seen in patients with del(8)(p23.1) and congenital heart disease. Based on these findings and recent studies showing that haploinsufficiency for other cardiac transcription factor genes (e.g., TBX5, NKX2-5) causes congenital heart disease, we postulate that GATA-4 deficiency may contribute to the phenotype of patients with monosomy of 8p23.1.

A comparison of standardized and narrative letters of recommendation

OBJECTIVE

To compare the Council of Emergency Medicine Residency Directors' (CORD's) standardized letters of recommendation (SLORs) with traditional narrative letters of recommendation (NLORs) with regard to interrater reliability, consistency, and time of interpretation.

METHODS

In part I of the study, four members of the residency selection committee each evaluated the same 20 SLORs and 20 NLORs from which all identifying characteristics had been deleted. Using Likert-type scales of the global assessment, each letter was assigned a numeric value from 1 to 7. The interrater reliability was calculated for both types of letters using the Kendall coefficient of concordance. Average time to interpretation of the letters was also determined. In part II, using the same numeric values as in part I, 207 single-author SLOR/NLOR pairs were evaluated to determine whether the global assessment of the SLOR was consistent with that of its partner NLOR. Interpretation of the NLOR was performed blinded to the SLOR. Statistical analysis was calculated using Spearman correlation coefficients.

RESULTS

In part I of the study, the interrater reliability of the SLOR was 0.97, as compared with 0.78 for the NLOR. The average time to interpret the global assessment of the SLOR was 16 seconds, vs 90 seconds for the NLOR. In part II of the study, of the 207 SLOR/NLOR pairs, 112 (54%) were assigned the same numeric value, 80 (39%) differed by one, 13 (6%) differed by two, and two (1%) differed by three, for an overall correlation of 0.58.

CONCLUSIONS

Compared with NLORs, the CORD SLOR offers better interrater reliability with less interpretation time. Single-author SLOR/NLOR pairs submitted for a single applicant do not correlate well. Residency selection committees must decide whether the added work of interpreting NLORs is beneficial.

Biodegradation and biocompatibility of a guided tissue regeneration barrier membrane formed from a liquid polymer material

Biodegradable barrier films were made by coagulating a solution of poly(DL-lactide) in N-methyl-2-pyrrolidone on porous polyethylene pads wetted with saline solution. The semisolid films were cut into 10 x 10 mm barriers and implanted subcutaneously in rabbits. At monthly intervals, the polymer implant sites were compared histologically to those implanted with USP negative control plastic. The polymer films were retrieved from the surrounding tissue, dried, weighed, and the changes in molecular weight determined using gel permeation chromatography. The molecular weight of the polymer decreased at a relatively constant rate over 5 months; however, no significant mass loss occurred until 5 months postimplantation. Also, no distinct histological differences were noted between the polymer barrier and the control plastic sites until 6 months when histiocytes and multinucleated giant cells showed a modest increase around fragmented polymer films. Similar barrier films also were fitted over naturally occurring buccal dehiscence defects in beagle dogs and the tissue sites compared histologically at 6 months to sham-operated control sites. New bone and dense connective tissues closely approximated segments of the remaining polymer and demonstrated the biocompatibility of the biodegradable films. Histomorphometric analyses of treated sites compared to sham controls showed that the polymer barrier is effective in promoting bone and cementum regeneration in periodontal defects in dogs.

The pharmacokinetic profile of a biodegradable controlled-release delivery system containing doxycycline compared to systemically delivered doxycycline in gingival crevicular fluid, saliva, and serum

The primary goal of this study was to characterize the release profile of doxycycline hyclate (8.5% w/w) from a biodegradable controlled-release delivery system (DH) placed in periodontal pockets. Pharmacokinetic data were obtained from gingival crevicular fluid (GCF), saliva, and serum of adult periodontitis patients. These results were compared to those obtained from individuals who received standard oral doses of doxycycline hyclate (200 mg on day 0, then 100 mg/day for 7 days). All participants presented with multiple pockets > or = 5 mm that bled upon probing. At the baseline visit patients receiving local drug delivery had all pockets > or = 5 mm that bled upon probing on one side of the mouth filled with DH. Drug retention was enhanced with 1 of 2 periodontal dressings (non-eugenol [NE] or 2-octyl cyanoacrylate [2-octyl]). Doxycycline concentrations were analyzed with the aid of reverse phase high performance liquid chromatography. GCF saliva, and serum samples were obtained just prior to drug delivery and then at hours 2, 4, 6, 8, 18, 24 and days 2, 3, 5, 7, and 8. GCF and saliva samples were also obtained at days 10, 14, 21, and 28. Thirty two subjects participated in the study; 13 in the NE group, 13 in the 2-octyl group, and 6 in the group taking oral doxycycline. The release of doxycycline in the GCF peaked at 2 hours (1473 microg/ml in the NE group, and 1986 microg/ml in the 2-octyl group). The mean concentration at day 7 was 309 microg/ml for the NE group and 148 microg/ml for the 2-octyl group. Minimal levels of drug were detected in the GCF of the oral doxycycline group with a peak concentration of 2.53 microg/ml at 12 hours. Salivary concentrations for both local delivery groups peaked at hour 2 (4.05 microg/ml for the NE group and 8.78 microg/ml for the 2-octyl group); by the end of day 1 levels were < or = 2 microg/ml. For subjects who took the oral doxycycline, salivary concentrations never exceeded 0.11 microg/ml. Serum concentrations of doxycycline for individuals receiving the local drug delivery never exceeded 0.1 microg/ml. For the oral doxycycline group serum concentrations ranged from 0.91 to 2.26 microg/ml over the 8 days data were collected. The high concentration of drug available at the treated sites coupled with the relatively low levels in the saliva and almost non-existent levels in the serum indicate that this biodegradable controlled-release delivery system displays an appropriate pharmacokinetic profile for the delivery of doxycycline into periodontal pockets.

Yeast PKA represses Msn2p/Msn4p-dependent gene expression to regulate growth, stress response and glycogen accumulation

Yeast cAMP-dependent protein kinase (PKA) activity is essential for growth and antagonizes induction of the general stress response as well as accumulation of glycogen stores. Previous studies have suggested that the PKA effects on the two latter processes result in part from transcription repression. Here we show that transcription derepression that accompanies PKA depletion is dependent upon the presence of two redundant Zn2+-finger transcription factors, Msn2p and Msn4p. The Msn2p and Msn4p proteins were shown previously to act as positive transcriptional factors in the stress response pathway, and our results suggest that Msn2p and Msn4p also mediate PKA-dependent effects on stress response as well as glycogen accumulation genes. Interestingly, PKA activity is dispensable in a strain lacking Msn2p and Msn4p activity. Thus, Msn2p and Msn4p may antagonize PKAdependent growth by stimulating expression of genes that inhibit growth. In agreement with this model, Msn2p/Msn4p function is required for expression of a gene, YAK1, previously shown to antagonize PKA-dependent growth. These results suggest that Msn2p/Msn4p-dependent gene expression may account for all, or at least most, of the pleiotropic effects of yeast PKA, including growth regulation, response to stress and carbohydrate store accumulation.

Equivalence in periodontal trials: a description for the clinician

There has been a tendency by clinicians in periodontal research to confuse lack of significance in a clinical trial designed for superiority for equivalence between the treatment arms. This paper is intended to define for the clinician what equivalency means in statistical terms. To demonstrate equivalence, the hypotheses and analysis specific to equivalence must be carried out; the information cannot be extracted directly from trials designed with superiority hypotheses and analysis. Further, acceptable mean differences in equivalency trials should be determined based not only on statistical considerations, but also on the clinical relevance of the proposed differences. The relationship between superiority and equivalency design and analysis is discussed and an example using a hypothetical clinical study is given.

Cdc1 and the vacuole coordinately regulate Mn2+ homeostasis in the yeast Saccharomyces cerevisiae

The yeast CDC1 gene encodes an essential protein that has been implicated in the regulation of cytosolic [Mn2+]. To identify factors that impinge upon Cdc1 or the Cdc1-dependent process, we isolated second-site suppressors of the conditional cdc1-1(Ts) growth defect. Recessive suppressors define 15 COS (CdcOne Suppressor) genes. Seven of the fifteen COS genes are required for biogenesis of the vacuole, an organelle known to sequester intracellular Mn2+. An eighth gene, COS16, encodes a vacuolar membrane protein that seems to be involved in Mn2+ homeostasis. These results suggest mutations that block vacuolar Mn2+ sequestration compensate for defects in Cdc1 function. Interestingly, Cdc1 is dispensable in a cos16delta deletion strain, and a cdc1delta cos16delta double mutant exhibits robust growth on medium supplemented with Mn2+. Thus, the single, essential function of Cdc1 is to regulate intracellular, probably cytosolic, Mn2+.

Cdc1 is required for growth and Mn2+ regulation in Saccharomyces cerevisiae

Cdc1 function was initially implicated in bud formation and nuclear division because cdc1(Ts) cells arrested with a small bud, duplicated DNA, and undivided nucleus. Our studies show that Cdc1 is necessary for cell growth at several stages of the cell cycle, as well as in pheromone-treated cells. Thus, Cdc1 depletion might affect bud formation and nuclear division, as well as other cellular processes, by blocking a process involved in general cell growth. Cells depleted of intracellular Mn2+ also exhibit a cdc1-like phenotype and recent results suggested Cdc1 might be a Mn2+-dependent protein. We show that all of the conditional Cdc1(Ts) alleles tested cause cells to become sensitive to Mn2+ depletion. In addition, Cdc1 overproduction alleviates the chelator sensitivity of several Mn2+ homeostasis mutants. These findings are compatible with a model in which Cdc1 regulates intracellular, and in particular cytosolic, Mn2+ levels which, in turn, are necessary for cell growth.

A homolog of mammalian, voltage-gated calcium channels mediates yeast pheromone-stimulated Ca2+ uptake and exacerbates the cdc1(Ts) growth defect

Previous studies attributed the yeast (Saccharomyces cerevisiae) cdc1(Ts) growth defect to loss of an Mn2+-dependent function. In this report we show that cdc1(Ts) temperature-sensitive growth is also associated with an increase in cytosolic Ca2+. We identified two recessive suppressors of the cdc1(Ts) temperature-sensitive growth which block Ca2+ uptake and accumulation, suggesting that cytosolic Ca2+ exacerbates or is responsible for the cdc1(Ts) growth defect. One of the cdc1(Ts) suppressors is identical to a gene, MID1, recently implicated in mating pheromone-stimulated Ca2+ uptake. The gene (CCH1) corresponding to the second suppressor encodes a protein that bears significant sequence similarity to the pore-forming subunit (alpha1) of plasma membrane, voltage-gated Ca2+ channels from higher eukaryotes. Strains lacking Mid1 or Cch1 protein exhibit a defect in pheromone-induced Ca2+ uptake and consequently lose viability upon mating arrest. The mid1delta and cch1delta mutants also display reduced tolerance to monovalent cations such as Li+, suggesting a role for Ca2+ uptake in the calcineurin-dependent ion stress response. Finally, mid1delta cch1delta double mutants are, by both physiological and genetic criteria, identical to single mutants. These and other results suggest Mid1 and Cch1 are components of a yeast Ca2+ channel that may mediate Ca2+ uptake in response to mating pheromone, salt stress, and Mn2+ depletion.

The BST1 gene of Saccharomyces cerevisiae is the sphingosine-1-phosphate lyase

Sphingolipids elicit a wide variety of eukaryotic cellular responses, most involving regulation of cell growth, differentiation, and apoptosis. Sphingosine 1-phosphate, a sphingolipid catabolite, is mitogenic in fibroblasts and inhibits the chemotactic mobility and invasiveness of human tumor cells. Sphingosine 1-phosphate degradation requires cleavage at the C2-3 carbon bond by sphingosine phosphate lyase. A yeast genetic approach was used to clone the first sphingosine phosphate lyase gene, BST1. BST1 overexpression conferred resistance to sphingosine in yeast. BST1 deletion produced sensitivity to exogenous D-erythro-sphingosine and phytosphingosine and intracellular accumulation of sphingosine 1-phosphate upon exposure to exogenous sphingosine. This study confirms that sphingoid base metabolism is similar in all eukaryotes and suggests that yeast genetics may be useful in the isolation and identification of other genes involved in sphingolipid signaling and metabolism.

Comparison of a bioabsorbable GTR barrier to a non-absorbable barrier in treating human class II furcation defects. A multi-center parallel design randomized single-blind trial

This multi-center single-blind study compared clinical outcomes following guided tissue regeneration (GTR) treating human Class II furcation defects with a new polylactic-acid-based bioabsorbable barrier (test treatment) or a non-absorbable ePTFE barrier (control treatment). Clinical parameters evaluated were change in vertical attachment level (VAL), horizontal attachment level (HAL), probing depth (PD), and gingival margin location (REC). Surgical treatment resulted in clinically and statistically equivalent changes when comparisons were made between test and control treatments. VAL gain was 2.0 mm for test and 1.6 mm for control groups; HAL gain was 2.1 mm for both test and control groups. PD reduction was 2.3 mm for the test group and 2.1 mm for the control group. Test sites experienced an additional 0.3 mm of recession beyond baseline; control sites, 0.5 mm. Within-group comparisons showed that the amount of recession was not significantly different from baseline in the test group. Recession in the control group was significantly different from baseline. All other parameters in both the test and control groups were significantly different from baseline. Evaluation of safety data indicated no significant differences between test and control treatments, although there was a strong trend for the control group to have more postoperative abscess or suppuration than test sites (control = 11; test = 4; P = 0.06).

Periodontal regeneration in naturally occurring Class II furcation defects in beagle dogs after guided tissue regeneration with bioabsorbable barriers

THE EFFICACY OF A BIOABSORBABLE polylactic acid based barrier was evaluated using naturally occurring buccal Class II furcation defects in beagle dogs. Sixteen furcation sites (8 control and 8 experimental) were treated in 6 adult animals. After full thickness flap reflection, exposed furcations and root surfaces were thoroughly root planed. In experimental sites a customized barrier was formed and fitted to cover the defect. Surgical flaps were replaced slightly coronal to the cemento-enamel junction. Animals were sacrificed at 6 months and specimens processed for histologic evaluation. Histologic and histometric analyses were done using 6 micrograms step serial sections in the buccal-lingual plane, corresponding to the buccal-lingual extent of the furcation. Results were: mean total defect experimental sites 1.92 mm; control sites 1.47 mm. Mean new cementum formation experimental sites 1.36 mm (71% of initial defect); control sites 0.25 mm (17% of initial defect). Mean new bone formation experimental sites 1.42 mm (74% of initial defect); control sites 0.20 mm (14% of initial defect). Mean junctional epithelium formation experimental sites 0.42 mm (22% of initial defect); control sites 1.21 mm (82% of initial defect). Statistical analysis demonstrated significant differences in all healing parameters favoring experimental (barrier-treated) sites. In this model, regeneration (new bone, cementum, and periodontal ligament) of 71% of the original defect in experimental sites and only 14% in control sites demonstrated a response that highly favored use of the barrier.

Socioeconomic status in ankylosing spondylitis: relationship between occupation and disease activity

OBJECTIVE

To identify the socioeconomic status through occupation of a large cohort of patients with ankylosing spondylitis (AS) and to determine possible relationships between occupation and clinical variables.

METHODS

We analyzed the employment status of 1,044 patients with AS.

RESULTS

85% of patients (890 of 1,044) were in full employment at the time of the assessment compared to 15% who were unemployed. When 50 employed patients were compared to 50 unemployed cases, the latter had increased disease activity and lower psychosocial well being.

CONCLUSION

Employed patients from the higher occupational group (I), had less disease activity, and lower pain and depression than patients from the lowest occupational group (IV).

Estrogenic and DNA-damaging activity of Red No. 3 in human breast cancer cells

Exposure to pesticides, dyes, and pollutants that mimic the growth promoting effects of estrogen may cause breast cancer. The pesticide DDT and the food colorant Red No. 3 were found to increase the growth of HTB 133 but not estrogen receptor (ER) negative human breast cells (HTB 125) or rat liver epithelial cells (RLE). Red No. 3, beta-estradiol, and DDT increase ER site-specific DNA binding to the estrogen response element in HTB 133 cells and increase cyclin-dependent kinase 2 activity in MCF-7 breast cancer cells. Site-specific DNA binding by p53 in RLE, HTB 125, HTB 133, and MCF-7 cells was increased when they were treated with Red No. 3, which suggests that cellular DNA was damaged by this colorant. Red No. 3 increased binding of the ER from MCF-7 cells to the estrogen-responsive element. Consumption of Red No. 3, which has estrogenlike growth stimulatory properties and may be genotoxic, could be a significant risk factor in human breast carcinogenesis.

Specific issues in clinical trials on the use of barrier membranes in periodontal regeneration

There are presently a number of different barriers available for use clinically in guided tissue regeneration (GTR) procedures. A number of trials using these techniques and comparing different types of barrier membranes are being published in the scientific literature. This review discusses issues related to clinical trials on the use of barrier membranes in periodontal regeneration. Outcome measures, both clinical and histological, are discussed in relation to results following GTR procedures. The difference between regeneration and repair is reviewed as well as methods of clinical and histologic assessment of both these outcomes. Data regarding the impact of patient variables and tooth or defect variables on outcomes are presented and suggestions for study designs are made based on these variables. Aspects of assessing for an appropriate sample size in superiority and equivalency trials using GTR techniques are presented as well as interpretation of results following these trials and their clinical significance.

Detection and functional characterization of p180, a novel cell cycle regulated yeast transcription factor that binds retinoblastoma control elements

In recent years it has become apparent that the cellular machinery governing cell cycle progression and transcription control are often homologous in yeast and mammalian cells. We and others have previously shown that the SP family of mammalian transcription factors regulates the transcription of a number of genes whose activities are governed by the product of the retinoblastoma (Rb) susceptibility gene, including c-FOS, c-MYC, TGFbeta-1, IGF-II, and c-JUN. To determine whether a similar pathway of transcriptional regulation may function in yeast, we explored the possibility that transcription factors with nucleotide-binding specificities akin to those of the SP family are expressed in Saccharomyces cerevisiae and Schizosaccharomyces pombe. Here we report the detection of novel yeast proteins (S. cerevisiae, p180; S. pombe, p200) that specifically bind Rb-regulated promoter elements in vitro dependent on nucleotides that are also required for binding and trans-activation by SP family members in vivo. Our results indicate that the S. cerevisiae retinoblastoma control element-binding activity 1) requires zinc for association with DNA; 2) does not bind to SCB, MCB, or E2F sites in vitro; 3) is cell cycle-regulated in a SWI6-independent fashion; and 4) maximally stimulates retinoblastoma control element-mediated transcription in early- to mid-S phase. Taken together, these data suggest that p180 may regulate the transcription of a subset of yeast genes whose expression is coincident with the onset and/or progression of DNA replication.