Blood and pituitary prolactin levels in tilapia (Sarotherodon mossambicus; teleostei) from different salinities as measured by a homologous radioimmunoassay

Highly purified prolactin (PRL) of the tilapia (t), Sarotherodon mossambicus, was injected into rats to produce antibodies. A satisfactory antiserum to the tPRL was used to develop a homologous radioimmunoassay (RIA) in which ¹²⁵I-tPRL was used as the label. The RIA sensitivity (minimal detectable dose) was 0.8 ng of tPRL standard per milliliter. Specificity of the assay was established by demonstrating negligible cross-reactivity of the antiserum with highly purified tilapia growth hormone, a gonadotropin fraction from tilapia pituitaries, and serum from hypophysectomized Sarotherodon. Furthermore, the RIA disclosed that tPRL is highly concentrated in the rostral pars distalis of tilapia kept in either fresh water (FW) or artificial seawater (ASW). The content of immunoreactive tPRL was 6–10 times greater in pituitaries of FW-adapted fish than in glands of those kept in ASW. Serum levels of tPRL were low in fish kept in 100% ASW and they increased 7- to 12-fold with adaptation to FW. Lowering the environmental salinity from 100 to 30% ASW increased the serum level of tPRL only slightly; the major increase in serum PRL concentration in response to hypotonic medium occurs when the environmental salinity is lowered below 10% ASW. Fish adapted to 100% ASW lacking either CaCl₂ or MgCl₂ did not show elevated serum PRL levels. These results indicated that in tilapia a major stimulus for prolactin secretion is reduced environmental NaCl and/or osmolarity.     

Optimal stimulus intensity and reliability of air stimulation technique for elicitation of laryngo-upper esophageal sphincter contractile reflex

To determine the optimal air stimulus intensity and duration for elicitation of the laryngo-upper esophageal sphincter (UES) contractile reflex, we studied 37 healthy volunteers 20 to 81 years of age. A sleeve device monitored the UES pressure. For laryngeal stimulation, we used an air stimulator unit (Pentax AP-4000) that incorporated a nasolaryngeal endoscope. The arytenoids and interarytenoid areas were stimulated at least three times by three different stimuli: 6-mm Hg air pulse with 50-ms duration, 10-mm Hg air pulse with 50-ms duration, and 6-mm Hg air pulse with 2-second duration. Of 1,165 air stimulations, 1,041 resulted in mucosal deflections. Of these, 451 resulted in an abrupt increase in UES pressure. The response/deflection ratio for 6-mm Hg stimulation with 2-second duration was significantly higher than those for air pulses with 50-ms duration (p < .001). We conclude that although the laryngo-UES contractile reflex can be elicited by an air pulse with 50-ms duration, this ultrashort stimulation is not reliable. Using longer-duration pulses (at least 2 seconds) improves the reliability of elicitation of the laryngo-UES contractile reflex.     

Pharmacotherapy and pharmacogenetics of nicotine dependence

The authors review recent advances in the pharmacotherapy and pharmacogenetics of nicotine dependence. Despite the negative health consequences of smoking, approximately 23% of adults in the United States are daily tobacco smokers and approximately 13% are nicotine dependent. Data for development of new medications for nicotine dependence are likely to come from animal models of the reinforcing value of nicotine, studies to identify proteins in transgenic rodents, and pharmacological studies of nicotine withdrawal. The initial pharmacogenetic studies of pharmacotherapies approved by the United States Food and Drug Administration for treatment of nicotine dependence-nicotine replacement (nicotine gum, nicotine nasal spray, and transdermal nicotine) and bupropion-have identified candidate alleles at the dopamine D2 receptor gene and mu opioid receptor gene that may predict therapeutic response. Because no one medication is likely to be safe and efficacious for a majority of persons with nicotine dependence, it will be useful to develop genetics-based methods and other tools to predict therapeutic response in subgroups of nicotine-dependent persons.     

Attaining and Maintaining Isometric and Isokinetic Goals of the Shaker Exercise

Previous studies have shown that the Shaker Exercise is effective in restoring oral intake in patients with deglutitive failure due to upper esophageal sphincter (UES) dysfunction. Our aim was to determine (1) exerciser compliance among healthy older adults, (2) number of days required to attain the isometric (IM) and isokinetic (IK) exercise goals, (3) rate and reason for dropout of exercisers, and (4) complaints associated with performance of the exercise. Twenty-six nondysphagic older adults were enrolled from an independent-living community (66–93 yr) to perform the Shaker Exercise. Each participant completed a questionnaire on exercise performance and its associated difficulties three times a day for six weeks. Four randomly chosen nondysphagic participants underwent pre- and postexercise videofluoroscopic swallow studies for biomechanical measurements. Maximum anterior hyoid and laryngeal excursions, as well as maximum anteroposterior UES opening increased (p < 0.05) following exercise. Duration to attain Shaker Exercise performance goals varied among participants. IK was more easily attained than IM. Only 50% and 70% of those enrolled initially were able to complete the exercise duration and attain its IK and IM goals, respectively. However, those who stayed in the program attained the IK and IM goals (100% and 74%, respectively). Most dropouts occurred in the first two weeks of exercise. Performance of the exercise was associated with mild muscle discomfort that resolved spontaneously after a couple of weeks. We concluded that although the Shaker Exercise can be performed independently, a structured and gradually progressive program is needed to attain the exercise goals completely.Supported in part by a grant from Retirement Research Foundation.     

Evaluation of seizure-like episodes in survivors of moderate and severe traumatic brain injury

BACKGROUND: Transient paroxysmal alterations of consciousness or behavior are common sequelae of moderate and severe traumatic brain injury (TBI). Clinicians caring for patients with such episodes often diagnose them as epileptic seizures, a frequent and well-studied complication of TBI. As it is difficult to confirm this diagnosis, antiepileptic drugs are often used empirically. However, as such therapy is frequently ineffective, we studied the usefulness of prolonged video electroencephalogram (VEEG) monitoring in the clinical management of paroxysmal behaviors in TBI survivors. METHODS: Records of patients referred evaluation in an epilepsy monitoring unit for management of medically intractable epilepsy were retrospectively reviewed. Patients with a documented history of moderate-to-severe brain injury preceding the onset of epilepsy were identified. These patients were studied by simultaneous videotape and scalp electroencephalographic recordings, and the majority also underwent magnetic resonance imaging and neuropsychologic studies. RESULTS: Of the 1858 consecutive admissions over a 66-month period, 127 (7%) fulfilled enrollment criteria. VEEG monitoring was conducted for an average of 4.6 days. Monitoring was successful in establishing a diagnosis in 82% of the cases referred: 62% had focal seizures, 6% had generalized seizures, and 33% had psychogenic nonepileptic seizures. Of those with temporal lobe epilepsy, 53% had mesial temporal sclerosis, as shown by magnetic resonance imaging. CONCLUSIONS: VEEG is a useful procedure in the evaluation of TBI survivors with spells. The yield of diagnoses that may alter treatment is substantial. Additionally, mesial temporal sclerosis is associated with TBI. Given the variety of seizure types found in survivors of moderate-to-severe TBI, obtaining specific diagnosis of seizure type by VEEG monitoring impacts treatment options.     

Pharmacokinetics, ovulation suppression and return to ovulation following a lower dose subcutaneous formulation of Depo-Provera

Depo-Provera is a highly effective contraceptive, given intramuscularly (150 mg/mL) once every 3 months. It has been in use in the United States for over 10 years. A new lower-dose formulation of Depo-Provera (104 mg/0.65 mL), has been developed that allows subcutaneous injection, potentially increasing the convenience, ease of administration and tolerability of this contraceptive. This prospective, randomized, single-center, single-dose trial evaluates the pharmacokinetics of the lower-dose formulation of Depo-Provera and compares the lower-dose formulation to the original formulation with regard to efficacy and duration of ovulation suppression and the return to ovulation at 12 months. While delivering a 30% lower total dose than the intramuscular formulation, the lower-dose formulation of Depo-Provera suppressed ovulation for more than 13 weeks in all subjects and was not affected by body mass index or race. Median time for return to ovulation was 30 weeks, with a 97.4% cumulative rate of return to ovulation at 12 months.