A system for tissue-specific gene targeting: transgenic mice susceptible to subgroup A avian leukosis virus-based retroviral vectors.

Avian leukosis viruses (ALVs) have been used extensively as genetic vectors in avian systems, but their utility in mammals or mammalian cell lines is compromised by inefficient viral entry. We have overcome this limitation by generating transgenic mice that express the receptor for the subgroup A ALV under the control of the chicken alpha sk-actin promoter. The skeletal muscles of these transgenic animals are susceptible to efficient infection by subgroup A ALV. Because infection is restricted to cell lineages that express the transgene, the method has utility for studies of development and oncogenesis and will provide models for tissue-specific gene therapy.     

5-HT3 agonist 2-methylserotonin as a training drug in discrimination studies.

Using a standard two-lever operant procedure, rats were trained to discriminate 5 mg/kg of the 5-HT3 agonist 2-methylserotonin (2-Me 5-HT; ED50 = 2.6 mg/kg) from saline using a VI 15-s schedule of reinforcement. The 2-Me 5-HT stimulus did not generalize to the 5-HT1/5-HT2 agonist 5-methoxy-N,N-dimethyltryptamine, but did generalize to the new 5-HT3 agonist 1-(m-chlorophenyl)biguanide (ED50 = 1.6 mg kg). The 5-HT3 antagonist ICS 205-930 potently antagonized the 2-Me 5-HT stimulus (ID50 = 0.001 mg/kg), whereas its quaternary amine analog, which does not readily penetrate the blood-brain barrier, failed to completely antagonize the 2-Me 5-HT stimulus at a 10,000-fold higher dose. The results of the present investigation show that 2-Me 5-HT serves as a discriminative stimulus in rats when paired with saline and suggest that its stimulus properties are likely mediated via a central 5-HT3 mechanism. As such, this is the first demonstration that a 5-HT3 agonist can be used as a training drug in drug discrimination studies.     

Admission blood pressure response as an indicator of hypertensive risk

In this retrospective study we aimed to identify from 50 outpatient (OP) mild hypertensives without clinical evidence of target organ damage (TOD), a group with unsustained hypertension in order to see whether they had less echocardiographic TOD than patients with sustained hypertension. Following OP assessment, patients were admitted to a hospital ward and BP was measured after 30 minutes' rest. In 21 patients (fallers) BP fell after admission and in 29 (non-fallers) BP either rose or remained the same (fallers = 164/102 OP v 152/93 mmHg hospital, non-fallers = 165/102 OP v 168/105 mmHg hospital, P less than 0.001 for SBP/DBP differences between the groups on hospitalisation). During the whole day after admission, ambulatory intra-arterial pressure (IABP) was consistently lower in the fallers (137/88 v 148/93 mmHg, P less than 0.04 for SBP, P = NS for DBP) and systolic variability was slightly but significantly higher (18 v 16 mmHg P = 0.05). Echocardiographically-assessed left ventricular mass index (LVMI) was significantly higher in the non-fallers (117 v 101 g/m2 P = 0.03) and correlated positively with mean systolic IABP in both groups although this only reached significance in the non-fallers (n = 25, r = 0.53 P less than 0.01 nonfallers v n = 18 r = 0.42 P = NS fallers). We believe the less sustained pressure of the fallers was responsible for their lower LVMIs and that an exaggerated defence reaction was operating when they were outpatients which relaxed following 30 minutes' rest in hospital. The study demonstrates the importance of sustained hypertension in the development of hypertensive cardiac TOD.     

Determination of procaine in equine plasma and urine by high-performance liquid chromatography.

The variability in plasma and urine equine procaine measurement between three independent laboratories using current methods led to the development of a sensitive, reliable, and reproducible high-performance liquid chromatographic method. Standardbred mares were administered either a penicillin G procaine preparation intramuscularly or procaine hydrochloride subcutaneously, and blood and urine were collected at defined time intervals. By HPLC the detection limits for procaine in plasma and urine were 1 and 10 ng/mL, respectively. In contrast procaine in plasma could not be detected by GC-NPD, while the urinary detection limit was 50 ng/mL. The concentration of fluoride in the collection tubes and repetitive freeze-thawing modified plasma procaine measurement. Urinary pH was a factor in estimation of urine procaine levels with greater recovery and reproducibility of results at pH 5 as compared to pH 7. This HPLC method provides a simple, sensitive, and reliable quantitation of procaine in equine plasma and urine.     

The FDA's new procedures for the use of investigational drugs in treatment

The Food and Drug Administration has established new procedures to make promising investigational drugs available for treatment of patients with immediately life-threatening or serious diseases as early in the drug development process as possible and well before general marketing begins. The purpose of this article is to inform the medical community about these new procedures and to facilitate their implementation. Examples of immediately life-threatening and serious diseases are given and the procedures that physicians should use to obtain a drug under the new regulations are described. The treatment use of zidovudine (Retrovir), while still in the investigational phase, is described as a case study. The article also summarizes the Food and Drug Administration's new procedures under which drug sponsors can charge for investigational drugs.     

Role of stereotactic biopsy in the management of transplant patients with intracranial lesions

Appropriate treatment of an intracranial lesion is based upon establishing a definitive diagnosis. CT-stereotactic biopsy procedures are highly accurate, are associated with few complications, and are usually performed only with local anesthesia. Stereotactic biopsy is the preferred method for histologically confirming the nature of an intracranial lesion in the immunocompromised patient. The mortality and morbidity approach 1 per cent, respectively. In the large reported series of stereotactic surgery for biopsy, diagnostic accuracy is over 95 per cent. Stereotactic techniques can also be used to aspirate abscesses or localize abscesses or neoplastic lesions excised by craniotomy.     

The filter properties of the arterial beds of organs in rats.

The frequency properties of arterial beds in organs were studied by temporarily ligating the renal, the gastric, the splenic or the superior mesenteric arteries of rats. Blood-pressure waves of the tail arteries were recorded before and during the ligations, and were analysed by Fourier's transformation. Their frequency spectra have been found to change profiles following specific patterns with the ligations of different arteries. The results were significant with regard to the frequency selectivities of the organic arterial beds. Such frequency properties can be clearly explained when the circulation system is viewed as an electrical circuit network in which the organic arterial beds work as filters.     

Iron deficiency anemia in children with exstrophy of the cloaca.

The clinical records of twenty-five children with exstrophy of the cloaca (EC) were retrospectively reviewed to evaluate the prevalence and the clinical characteristics of iron deficiency anemia (IDA). Five of the 25 children with EC (20 %) exhibited IDA at some point. Their ages at the time of diagnosis were between 1.9 and 13.0 years. In the four cases where IDA was thought to be related to iron malabsorption secondary to short-bowel syndrome, its treatment required longer periods of iron supplementation to correct the anemia and to restore the total body iron stores. Physicians caring for children with EC should monitor for and treat IDA as part of a comprehensive management plan.     

Expression profiling of metalloproteinases and inhibitors in cartilage

Objective   To profile the expression of all known members of the matrix metalloproteinase ( MMP ), a disintegrin and metalloproteinase with thrombospondin motifs ( ADAMTS ), and tissue inhibitor of metalloproteinases ( TIMP s) gene families in normal cartilage and that from patients with osteoarthritis (OA).
Methods   Human cartilage was obtained from femoral heads at joint replacement for either osteoarthritis or following fracture to the neck of femur. Total RNA was purified and expression of genes assayed using quantitative real-time PCR.
Results   Several members of the above gene families were regulated in OA. Genes increasing in expression in OA were: at P  < 0.001, MMP-13 , MMP-28 , ADAMTS-16 ; at P  < 0.01, MMP-9 , MMP-16 , ADAMTS-2 , ADAMTS-14 and at P  < 0.05, MMP-2 , TIMP-3 , ADAMTS-12 . Genes decreasing in expression in OA were: at P  < 0.001, MMP-1 , MMP-3 , ADAMTS-1 ; at P  < 0.01, MMP-10 , TIMP-1 , ADAMTS-9 and at P  < 0.05, TIMP-4 , ADAMTS-5 , ADAMTS-15 . Correlation analysis revealed that groups of genes across the gene families are co-expressed in cartilage.
Conclusion   This is the first comprehensive expression profile of all known MMP , ADAMTS and TIMP genes in cartilage. Patterns of expression provide a foundation on which to understand mechanisms of gene regulation in OA and potentially for refining the specificity of anti-proteolytic therapies.     

Morphine Preconditions Purkinje Cells against Cell Death under In Vitro Simulated Ischemia-Reperfusion Conditions

Background: Morphine pretreatment via activation of [delta]1-opioid receptors induces cardioprotection. In this study, the authors determined whether morphine preconditioning induces ischemic tolerance in neurons.

Methods: Cerebellar brain slices from adult Sprague-Dawley rats were incubated with morphine at 0.1-10 [mu]m in the presence or absence of various antagonists for 30 min. They were then kept in morphine- and antagonist-free buffer for 30 min before they were subjected to simulated ischemia (oxygen-glucose deprivation) for 20 min. After being recovered in oxygenated artificial cerebrospinal fluid for 5 h, they were fixed for morphologic examination to determine the percentage of undamaged Purkinje cells.

Results: The survival rate of Purkinje cells was significantly higher in slices preconditioned with morphine (>= 0.3 [mu]m) before the oxygen-glucose deprivation (57 +/- 4% at 0.3 [mu]m morphine) than that of the oxygen-glucose deprivation alone (39 +/- 3%, P < 0.05). This morphine preconditioning-induced neuroprotection was abolished by naloxone, a non-type-selective opioid receptor antagonist, by naltrindole, a selective [delta]-opioid receptor antagonist, or by 7-benzylidenenaltrexone, a selective [delta]1-opioid receptor antagonist. However, the effects were not blocked by the [mu]-, [kappa]-, or [delta]2-opioid receptor antagonists, [beta]-funaltrexamine, nor-binaltorphimine, or naltriben, respectively. Morphine preconditioning-induced neuroprotection was partially blocked by the selective mitochondrial adenosine triphosphate-sensitive potassium channel antagonist, 5-hydroxydecanoate, or the mitochondrial electron transport inhibitor, myxothiazol. None of the inhibitors used in this study alone affected the simulated ischemia-induced neuronal death.