Melatonin Receptors on Ovine Pars Tuberalis: Characterization and Autoradiographicai Localization

The functional significance of the pars tuberalis (PT) of the mammalian adenohypophysis has remained an enigma (1, 2). One view of its function is that it acts as an auxiliary gland to support the endocrine role of the pars distalis (PD) (2), as it has been shown to contain immunocytochemically identifiable thyrotrophs and gonadotrophs (1). Many of the cells of the PT are, however, ultrastructurally unique suggesting an independent function for this tissue. Our recent demonstration that the PT of the rat is a major binding site for the ligand iodomelatonin lends further support to this idea (3). We have utilized the highly specific ligand [¹²⁵l]melatonin, and have demonstrated that it binds exclusively, with very high affinity, to the PT but not the PD of the adult sheep adenohypophysis. These findings support the conclusion that the PT has a distinct role in relation to melatonin action and seasonal reproduction.     

A randomized multicenter study to determine the efficacy of activity restriction for preterm labor management in patients testing negative for fetal fibronectin.

OBJECTIVE: To assess the impact of activity restriction (AR) on the incidence of preterm birth in women treated for preterm labor testing negative for fetal fibronectin (fFN). STUDY DESIGN: Women who were diagnosed with preterm labor and tocolyzed with magnesium sulfate were concurrently screened with fFN for the purpose of subsequent management. Included were consenting patients with negative fFN, gestational age 23 0/7-33 6/7 weeks, cervical dilation < or =3 cm, and minimal vaginal bleeding. Patients were randomized to AR or no AR. Primary study outcome was incidence of preterm delivery and interval from randomization to delivery. RESULTS: A total of 73 women with negative fFN were randomized (36 with AR, 37 without AR). The overall preterm birth rate was 40%, with 44.4% of patients with AR and 35.1% of patients without AR delivering preterm, p=0.478. CONCLUSION: Maternal AR did not impact pregnancy outcome. The incidence of preterm birth in symptomatic women testing fFN negative was higher than previously reported.     

Neuropsychological predictors of self-neglect in cognitively impaired older people who live alone.

OBJECTIVE: The authors examined the accuracy of certain neuropsychological tests in the prediction of harm resulting from self-neglect in cognitively impaired seniors who lived alone. METHODS: The study included 130 participants, aged 65 and older, who scored less than 131 on the Dementia Rating Scale. Neuropsychological tests were administered at baseline, resulting in eight predictive scores. Informants and primary care physicians provided information about harm that occurred to the participants during the 18-month prospective follow up. An incident was defined as harmful if it occurred as the result of self-neglect or disorientation and resulted in physical injury or property loss or damage and required emergency interventions. Proportional hazard regression analysis was conducted to examine the predictive relationship between the eight neuropsychological tests and time to incident harm with age, sex, education, the Charlson Comorbidity Index, and the Mini-Mental State Examination included in the model as covariates. RESULTS: Twenty-seven participants experienced harm during the 18-month follow-up period. A proportional hazards model indicated that three neuropsychological tests, which measured recognition memory, executive functioning, and conceptualization, were independent risk factors for harm. CONCLUSIONS: These findings provide insight into why harm occurred in these cognitively impaired elders who lived alone. They also support the ecologic validity of these tests and suggest directions for the development of intervention strategies for harm prevention.     

Rapid prototype patient-specific drill template for cervical pedicle screw placement.

OBJECTIVE: To assess the feasibility and accuracy of a drill template for the placement of a cervical pedicle screw in a single vertebral level. MATERIALS AND METHODS: A volumetric CT scan was performed on a cadaver cervical spine. Using computer software, a drill template with a predefined trajectory was constructed that was designed to match the posterior surface of the right side of the fifth cervical vertebra. A physical template was created from the computer model using a rapid prototyping machine. The drill template was used to guide drilling of a pilot hole, and a CT scan was performed to assess the accuracy of this hole. A 3.5-mm diameter pedicle screw was placed in the pilot hole. The spine was then dissected to separate the vertebrae and the trajectory of the screw was visually inspected. RESULTS: The feasibility of this patient-specific rapid prototyping technique was demonstrated. Imaging and visual inspection confirmed accurate placement of the pilot hole and cervical pedicle screw without cortical violation. CONCLUSIONS: The potential use of drill templates to place cervical pedicle screws is promising. Our initial methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the cervical spine.     

Trigeminal autonomic cephalalgias. Part 3: short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing.

Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) is a syndrome characterized by severe, strictly unilateral short-lasting (between 5 and 240 seconds) pain localized to orbital, supraorbital, and temporal areas, accompanied by ipsilateral conjunctival injection and lacrimation. It represents 1 of 3 primary headaches classified as trigeminal autonomic cephalalgias (TACs). Although its prevalence is extremely small, SUNCT patients may present at dental offices seeking relief for their pain. It is important for oral health care providers to recognize SUNCT and render an accurate diagnosis. This will avoid the pitfall of implementing unnecessary and inappropriate traditional dental treatments in hopes of alleviating this neurovascular pain. The following article is part 3 of a review on TACs and focuses on SUNCT. Aspects of SUNCT, including epidemiology, genetics, pathophysiology, clinical presentation, classification and variants, diagnosis, medical management, and dental considerations are discussed.     

Differential effects of within-day continuous vs. transient dopamine D2 receptor occupancy in the development of vacuous chewing movements (VCMs) in rats.

Accumulating evidence suggests that antipsychotics (APs) that lead to sustained blockade of dopamine D(2) receptors are more likely to induce acute extrapyramidal side effects (EPS) compared to APs that only occupy D(2) receptors transiently. It is unclear, however, whether a similar relationship exists for long-term AP-induced motoric side effects like tardive dyskinesia (TD). The objective of this study was to ascertain whether transient (via daily subcutaneous (s.c.) injections) vs continuous (via osmotic minipump) AP-induced D(2) receptor occupancy differentially affects the development of haloperidol-induced vacuous chewing movements (VCMs), an animal model of TD. Six groups of 12 rats received 0.1, 0.25, or 1 mg/kg of haloperidol or vehicle (n=36) via osmotic minipump (to provide within-day sustained) or daily s.c. injection (within-day transient) for 8 weeks. VCMs were measured on a weekly basis and D(2) occupancy levels were measured in vivo using [(3)H]-raclopride at the end of the experiment. Minipump-treated rats developed HAL dose-dependent D(2) occupancies of 0.1 mg/kg/day (57%), 0.25 mg/kg/day (70%), and 1 mg/kg/day (88%). S.C.-treated rats also developed HAL dose-dependent D(2) occupancies of 0.1 mg/kg/day (83% peak, 3% trough), 0.25 mg/kg/day (89% peak, 0% trough), and 1 mg/kg/day (94% peak, 17% trough). A total of 43% of rats given 0.25 and 1 mg/kg/day of HAL via minipump developed high VCMs compared to only 8% of the rats given the same doses via daily s.c. injections. The 0.1 mg/kg dose did not give rise to VCMs beyond vehicle levels regardless of the route of administration. These findings support the contention that D(2) occupancy levels induced by chronic HAL must be high and sustained through the day before significant risk of VCMs, and perhaps also TD, emerges.     

Persistent Low-frequency Spontaneous Discharge in A-fiber and C-fiber Primary Afferent Neurons during an Inflammatory Pain Condition

Background: Primary afferent nociceptor sensitization and its accompanying spontaneous discharge are believed to be the proximate cause of the spontaneous pain and hypersensitivity that follow an acute tissue injury. Evidence for this comes almost entirely from studies limited to the first few minutes to an hour or two after injury, when the inflammatory reaction to injury has just begun. However, there is evidence that inflammatory pain mechanisms differ from acute pain mechanisms and that the mechanisms that drive and modulate inflammatory pain may evolve over time.

Methods: The authors surveyed spontaneous afferent discharge in rats with hind paw inflammation evoked by complete Freund adjuvant over the entire 14 days of the inflammatory pain condition, as determined in parallel experiments assessing allodynia and hyperalgesia.

Results: Inflammation-evoked heat hyperalgesia, mechanoallodynia, and mechanohyperalgesia began within hours, persisted until at least day 7, and resolved by day 14. A large percentage (23%) of A fibers had spontaneous discharge 2 days after inflammation, but the incidence was much reduced (to 7-9%) by 7 and 14 days. At all times, the A-fiber discharge frequency was low (<3.0 Hz) or very low (<0.3 Hz). A large percentage (24%) of C fibers had spontaneous discharge 2 and 7 days after inflammation, but this also declined to near control levels by day 14; C-fiber discharge frequency was also always low (most at 0.3-1.0 Hz).