Inhibition by AICA riboside of gluconeogenesis in isolated rat hepatocytes.

5-Amino-4-imidazolecarboxamide (AICA) riboside, the nucleoside corresponding to AICA ribotide (AICAR or ZMP), an intermediate of the de novo pathway of purine biosynthesis, was found to exert a dose-dependent inhibition on gluconeogenesis in isolated rat hepatocytes. Production of glucose from lactate-pyruvate mixtures was half-maximally inhibited by approximately 100 microM and completely suppressed by 500 microM AICA riboside. AICA riboside also inhibited the production of glucose from all other gluconeogenic precursors investigated, i.e., fructose, dihydroxyacetone, and L-proline. Measurements of intermediates of the glycolytic-gluconeogenic pathway showed that AICA riboside provoked elevations of triose phosphates and fructose-1,6-bisphosphate and decreases in fructose-6-phosphate and glucose-6-phosphate. The effects of AICA riboside persisted when the cells were washed 10 min after its addition but were suppressed by 5-iodotubercidin, an inhibitor of adenosine kinase. AICA riboside provoked a dose-dependent buildup of normally undetectable Z nucleotides. After 20 min of incubation with 500 microM AICA riboside, ZMP, ZTP, and ZDP reached 3, 0.3, and 0.1 mumol/g cells, respectively. Concentrations of ATP were not significantly modified by addition of up to 500 microM AICA riboside when the cells were incubated with lactate-pyruvate but decreased with fructose or dihydroxyacetone. The activity of rat liver fructose-1,6-bisphosphatase was inhibited by ZMP with an apparent Ki of 370 microM. It is concluded that AICA riboside exerts a suppressive effect on gluconeogenesis because it provokes an accumulation of ZMP, which inhibits fructose-1,6-bisphosphatase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clerkship directors' perceptions of the impact of HCFA documentation guidelines.

PURPOSE: Chart notes are used to support billing codes under the evaluation and management guidelines of the Health Care Financing Administration (HCFA), in addition to serving as a record of the visit. To better understand the effect of the HCFA documentation guidelines, the authors collected data on how the guidelines affect participation by university- and community-based faculty in clinical education programs. METHOD: In 2000, the authors sent six copies of their questionnaire to the associate deans of the 125 U.S. medical schools and requested they distribute them to all core clerkship directors. The questionnaire consisted of multiple-choice and short-answer questions regarding documentation of medical visits, participation of community-based faculty, understanding of HCFA documentation guidelines, and effects on education programs. RESULTS: The response rate was about 50%. Most of the 379 clerkship directors who responded (77%) stated they were aware the HCFA documentation guidelines include specifications regarding the role medical students can play and documentation of medical visits, and 64% indicated they were concerned the guidelines would affect their educational programs. Concerns included the loss of student independence and active participation in the patient care environment (37), time constraints and the changing balance between education and service (16), loss of faculty and decreased morale (11), and decreased quality of care for patients (7). CONCLUSION: Leaders of medical education must work to modify these guidelines to protect the quality of patients' care, while maximizing students' educational opportunity and participation.     

Adrenergic signalling between rat taste receptor cells

In taste buds, synaptic transmission is traditionally thought to occur from taste receptor cells to the afferent nerve. This communication reports the novel observation that taste receptor cells respond to adrenergic stimulation. Noradrenaline application inhibited outward potassium currents in a dose-dependent manner. This inhibition was mimicked by the β agonist isoproterenol and blocked by the β antagonist propranolol. The α agonists clonidine and phenylephrine both inhibited the potassium currents and elevated intracellular calcium levels. Inwardly rectifying potassium currents were unaffected by adrenergic stimulation. Experiments using the RT-PCR technique demonstrate that lingual epithelium expresses multiple α (α1a, α1b, α1c, α1d, α2a, α2b, α2c) and β (β1, β2) subtypes of adrenergic receptors, and immunocytochemistry localized noradrenaline to a subset of taste receptor cells. Collectively, these data imply strongly that adrenergic transmission within the taste bud may play a paracrine role in taste physiology.     

Reassessment of CD62L as a marker of pre-effector T cells in the tumor draining lymph nodes of head and neck cancer patients.

OBJECTIVES: CD62L was evaluated as a determinant of human pre-effector T cells. STUDY DESIGN AND SETTING: Phenotype and cytokine secretion profiles of CD62L cells were determined based on activation status. RESULTS: CD62L(Low) T cells demonstrated significantly higher secretion of interleukin (IL)-10 and interferon (IFN)-gamma than did CD62L(High) T cells. After activation, the majority of cells expressed high levels of the CD62L surface marker. Postactivation levels of IL-10 production remained elevated or unchanged. In a murine B16 melanoma model, freshly isolated CD62L(Low) tumor draining lymph nodes (TDLN) T cells showed increased secretion of IL-2 and IL-4 but not of IL-10 or IFN-gamma. The surface expression of CD62L and cytokine secretion patterns were maintained after activation with concomitant increases in IL-10. CONCLUSION: Our results provide evidence that CD62L(Low) T cells in TDLNs of progressively growing squamous cell carcinoma of the head and neck differ phenotypically and functionally from those of mouse origin. SIGNIFICANCE: Characterization of this human CD62L(Low) T cell population provides initial insight regarding novel surface markers in TDLN T cells that might correlate with antitumor reactivity.     

Preliminary outcomes and efficacy of the first 360 consecutive kyphoplasties for the treatment of painful osteoporotic vertebral compression fractures.

BACKGROUND CONTEXT: Osteoporosis is a major cause of morbidity in worldwide elderly populations. Patients may become susceptible to vertebral compression fractures (VCFs) from low-impact situations. For patients who have failed conventional, palliative medical therapy, kyphoplasty not only reduces pain associated with vertebral fractures, but also offers a minimally invasive procedure with the potential to address fracture reduction and spinal sagittal alignment. Kyphoplasty involves expanding an inflatable balloon tamp to create a cavity within a vertebral body before cement deposition. PURPOSE: To evaluate the safety and efficacy of kyphoplasty to reduce and fix painful osteoporotic VCFs. STUDY DESIGN/SETTING: A retrospective, single-arm cohort study of consecutive kyphoplasty patients treated at a single center. PATIENT SAMPLE: Three hundred sixty VCFs were treated during 254 kyphoplasty procedures on 222 osteoporotic patients (mean age, 76 years [range, 28-98]; 28% male and 72% female). OUTCOME MEASURES: Patient-reported pain ratings were examined. Cement extravasation was monitored by intraoperative fluoroscopy and on postoperative radiographs. Anterior and midline vertebral height were assessed from standing, lateral radiographs obtained preoperatively and postoperatively. The number of patients who returned with symptomatic, new fractures was monitored. Perioperative complications were recorded. Mean follow-up occurred 21 months after kyphoplasty (range, 6 months through 36 months). RESULTS: Immediate pain relief was reported by 89% of patients by the first follow-up visit. One patient experienced postoperative pain as a result of radiculopathy related to bone filler leakage into the foramen. The remaining patients had persistent pain and were diagnosed with either a new fracture or underlying degenerative disc disease. Greater than or equal to 20% restoration of lost vertebral height (anterior) was observed in 63% of fractures with an overall mean restoration of 30%, and > or = 20% restoration of lost vertebral height (midline) was detected in 69% of fractures with an overall mean restoration of 50%. In this cohort, 12% (30/254) of the patients required additional kyphoplasty procedures to treat 36 symptomatic, new adjacent and remote fractures. No device-related complications occurred. CONCLUSIONS: Kyphoplasty is a safe and effective, minimally invasive procedure for relief of pain associated with VCF. In our series we also demonstrated some restoration of vertebral height and partial correction of sagittal alignment.     

Prophylactic human papillomavirus vaccines: the beginning of the end of cervical cancer

Persistent infection with one of the oncogenic human papillomavirus (HPV) types is a necessity for the development of cervical cancer. By HPV vaccination, cervical cancer could become a very rare disease. Two types of HPV vaccines can be distinguished: (i) therapeutic vaccines which induce cellular immunity targeted against epithelial cells infected with HPV and (ii) prophylactic vaccines inducing virus-neutralizing antibodies protecting against new but not against established infections. At present, several vaccines have been developed and tested in clinical trials. The vaccines are generally well tolerated and highly immunogenic. The current clinical data indicate that prophylactic vaccines are very effective against new persistent infections and the development of cervical intraepithelial lesions. The protection is type specific. However, the follow-up of the vaccination trials is still short. The effect of HPV vaccines on future cancer incidence will only be known after decades of follow-up. This article will address the status of recently terminated phase II and currently running phase III trials with prophylactic HPV vaccines.     

CAR2 displays unique ligand binding and RXRalpha heterodimerization characteristics.

The constitutive androstane receptor (CAR; NR1I3) regulates the expression of genes involved in xenobiotic metabolism. Alternative splicing of the human CAR gene yields an array of mRNAs that encode structurally diverse proteins. One form of CAR, termed CAR2, contains an additional four amino acids (SPTV) that are predicted to reshape the ligand-binding pocket. The current studies show a marked, ligand-independent, CAR2-mediated transactivation of reporters containing optimal DR-3, DR-4, and DR-5 response elements, and reporters derived from the natural CYP2B6 and CYP3A4 gene promoters. Overexpression of the RXRalpha ligand binding domain was critical for achieving these effects. CAR2 interaction with SRC-1 was similarly dependent on the coexpression of RXRalpha. Mutagenesis of Ser233 (SPTV) to an alanine residue yielded a receptor possessing higher constitutive activity. Alternatively, mutating Ser233 to an aspartate residue drastically reduced the transactivation capacity of CAR2. The respective abilities of these mutagenized forms of CAR2 to transactivate a DR-4 x 3 reporter element correlated with their ability to interact with RxRalpha and to recruit SRC-1 in a ligand-regulated manner. Together, these results demonstrate a robust RXRalpha-dependent recruitment of coactivators and transactivation by CAR2. In addition, CAR2 displays novel dose responses to clotrimazole and androstanol compared with the reference form of the receptor while at the same time retaining the ability to bind CITCO. This result supports a hypothesis whereby the four-amino-acid insertion in CAR2 structurally modifies its ligand binding pocket, suggesting that CAR2 is regulated by a set of ligands distinct from those governing the activity of reference CAR.