Reduced hippocampal glutamate in Alzheimer disease

Altered neurometabolic profiles have been detected in Alzheimer disease (AD) using (1)H magnetic resonance spectroscopy (MRS), but no definitive biomarker of mild cognitive impairment (MCI) or AD has been established. This study used MRS to compare hippocampal metabolite levels between normal elderly controls (NEC) and subjects with MCI and AD. Short echo-time (TE=46 ms) (1)H spectra were acquired at 4T from the right hippocampus of 23 subjects with AD, 12 subjects with MCI and 15 NEC. Absolute metabolite levels and metabolite ratios were compared between groups using a multivariate analysis of covariance (covariates: age, sex) followed by post hoc Tukey's test (p<0.05 significant). Subjects with AD had decreased glutamate (Glu) as well as decreased Glu/creatine (Cr), Glu/myo-inositol (mI), Glu/N-acetylaspartate (NAA), and NAA/Cr ratios compared to NEC. Subjects with AD also had decreased Glu/mI ratio compared to MCI. There were no differences between subjects with MCI and NEC. Therefore, in addition to NAA/Cr, decreased hippocampal Glu may be an indicator of AD.

Relationship between degree of viremia and disease manifestation in calves with experimentally induced bovine viral diarrhea virus infection

OBJECTIVE

To compare degree of viremia and disease manifestations in calves with type-I and -II bovine viral diarrhea virus (BVDV) infection.

ANIMALS

16 calves.

PROCEDURE

Colostrum-deprived calves obtained immediately after birth were assigned to 1 control and 3 treatment groups (4 calves/group). Calves in treatment groups were inoculated (day 0) by intranasal instillation of 10(7) median tissue culture infective dose BVDV 890 (type II), BVDV 7937 (type II), or BVDV TGAN (type I). Blood cell counts and virus isolation from serum and leukocytes were performed daily, whereas degree of viremia was determined immediately before and 4, 6, 8, and 12 days after inoculation. Calves were euthanatized on day 12, and pathologic, virologic, and immunohistochemical examinations were performed.

RESULTS

Type-II BVDV 890 induced the highest degree of viremia, and type-I BVDV TGAN induced the lowest. Virus was isolated more frequently and for a longer duration in calves inoculated with BVDV 890. A parallel relationship between degree of viremia and rectal temperature and an inverse relationship between degree of viremia and blood cell counts was observed. Pathologic and immunohistochemical examinations revealed more pronounced lesions and more extensive distribution of viral antigen in calves inoculated with type-II BVDV.

CONCLUSIONS AND CLINICAL RELEVANCE

Degree of viremia induced during BVDV infection is associated with severity of clinical disease. Isolates of BVDV that induce a high degree of viremia may be more capable of inducing clinical signs of disease. Strategies (eg, vaccination) that reduce viremia may control clinical signs of acute infection with BVDV.

In vivo pharmacological characterization of SoRI 9409, a nonpeptidic opioid mu-agonist/delta-antagonist that produces limited antinociceptive tolerance and attenuates morphine physical dependence

Repeated exposure to mu-opioid analgesics produces unwanted side effects, including tolerance and physical dependence. delta-Opioid antagonists attenuate development of morphine tolerance and physical dependence. We recently reported that SoRI 9409, a mixed mu-agonist/delta-antagonist, produces antinociception with limited development of tolerance after repeated i.c.v. injections. The current studies report on a more complete characterization of the compound in male ICR mice. SoRI 9409 produced limited antinociceptive effects in the 55 degrees C tail-flick test and full agonist effects in the acetic acid writhing assay after i.c.v. or i.p. administration. Repeated i.p. administration of A(90) doses of SoRI 9409 did not produce tolerance. The agonist effects of the compound were preferentially blocked by the mu-selective antagonist beta-funaltrexamine. The kappa-antagonist nor-binaltorphimine produced partial antagonism, whereas the delta-antagonist naltrindole had no effect on SoRI 9409 antinociception. Intraperitoneal administration of SoRI 9409 preferentially antagonized the antinociceptive actions of the delta-2 agonist [D-Ala(2),Glu(4)]deltorphin over the delta-1 agonist cyclic[D-Pen(2),D-Pen(5)]-enkephalin and the mu-agonist [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin. SoRI 9409 did not antagonize the antinociceptive effects of the kappa-agonist U69,593 (doses up to 60 mg/kg). SoRI 9409 (10 mg/kg i.p.) elicited much less vertical jumping than naloxone (10 mg/kg i.p.) in acute and chronic morphine dependence models. SoRI 9409 also suppressed withdrawal jumping when coadministered with naloxone. These studies indicate that SoRI 9409 acts primarily as a partial mu-agonist/delta-antagonist and supports the hypothesis that this type of compound may have a better therapeutic profile than currently available mu-agonists.

Synthesis, opioid receptor binding, and biological activities of naltrexone-derived pyrido- and pyrimidomorphinans

A series of pyrido- and pyrimidomorphinans (6a-h and 7a-g) were synthesized from naltrexone and evaluated for binding and biological activity at the opioid receptors. The unsubstituted pyridine 6a displayed high affinities at opioid delta, mu, and kappa receptors with K(i) values of 0.78, 1.5, and 8.8 nM, respectively. Compound 6a was devoid of agonist activity in the mouse vas deferens (MVD) and guinea pig ileum (GPI) preparations but was found to display moderate to weak antagonist activity in the MVD and GPI with K(e) values of 37 and 164 nM, respectively. The pyrimidomorphinans in general displayed lower binding potencies and delta receptor binding selectivities than their pyridine counterparts. Incorporation of aryl groups as putative delta address mimics on the pyrido- and pyrimidomorphinan framework gave ligands with significant differences in binding affinity and intrinsic activity. Attachment of a phenyl group at the 4'-position of 6a or the equivalent 6'-position of 7a led to dramatic reduction in binding potencies at all the three opioid receptors, indicating the existence of a somewhat similar steric constraint at the ligand binding sites of delta, mu, and kappa receptors. In contrast, the introduction of a phenyl group at the 5'-position of 6a did not cause any reduction in the binding affinity at the delta receptor. In comparison to the unsubstituted pyridine 6a, the 5'-phenylpyridine 6c showed improvements in mu/delta and kappa/delta binding selectivity ratios as well as in the delta antagonist potency in the MVD. Interestingly, introduction of a chlorine atom at the para position of the pendant 5'-phenyl group of 6c not only provided further improvements in delta antagonist potency in the MVD but also shifted the intrinsic activity profile of 6c from an antagonist to that of a mu agonist in the GPI. Compound 6d thus possesses the characteristics of a nonpeptide mu agonist/delta antagonist ligand with high affinity at the delta receptor (K(i) = 2.2 nM), high antagonist potency in the MVD (K(e) = 0.66 nM), and moderate agonist potency in the GPI (IC(50) = 163 nM). Antinociceptive evaluations in mice showed that intracerebroventricular (icv) injections of 6d produced a partial agonist effect in the 55 degrees C tail-flick assay and a full agonist effect in the acetic acid writhing assay (A(50) = 7.5 nmol). No signs of overt toxicity were observed with this compound in the dose ranges tested. Moreover, repeated icv injections of an A(90) dose did not induce any significant development of antinociceptive tolerance in the acetic acid writhing assay. The potent delta antagonist component of this mixed mu agonist/delta antagonist may be responsible for the diminished propensity to produce tolerance that this compound displays.

Guidelines for the Department of Transportation physical examination

Primary care providers commonly perform the mandatory Department of Transportation Federal Highway Administration physical examination for individuals who drive commercial motor vehicles. Although these examinations may be offered at the worksite or in occupational health clinics, many drivers prefer to have them performed in the primary care setting. Performing the examination and subsequently certifying the driver is a highly regulated process with potentially serious consequences for the driver, the examiner, and the public. This article discusses the regulations and recommendations for certification of commercial drivers and the problems commonly encountered in the clinical setting.

The effect of epithelium removal on non-adrenergic, non-cholinergic inhibitory responses in the isolated central airways of the cat and guinea pig

Epithelium removal from the feline or the indomethacin-treated guinea pig trachea had no effect on tissue sensitivity or responsiveness to the contractile actions of pharmacological agonists or electrical field stimulation. In the feline hilar bronchus, epithelium removal had no effect on tissue sensitivity or responsiveness to acetylcholine or electrical field stimulation but increased bronchial sensitivity to serotonin without affecting responsiveness. Non-adrenergic non-cholinergic (NANC) relaxation responses elicited by electrical field stimulation in airway preparations from either species were unaffected by epithelium removal. These results suggest that the epithelium does not modulate contractile responses in the feline trachea but may modulate the actions of specific contractile agonists in the feline hilar bronchus. Further, NANC relaxation responses appear to occur independently of the airway epithelium.

Novel degradation products from the treatment of salinomycin and narasin with formic acid

Salinomycin and narasin (4-methylsalinomycin) upon treatment with HCO2H furnish the known furanone fragment 3 and the complementary but rearranged fragments 1 and 2 respectively. The structure of 1 has been established by X-ray analysis. Upon being heated under reflux in PhMe, 1 undergoes the retrograde aldol reaction to furnish alpha, gamma-dimethyl-2-furanbutanal (4). The furan moiety of 1 is more resistant to electrophilic substitution than expected, but it can be acylated by highly reactive reagents such as (CF3CO)2O and AcOSO2Me. Compounds 1 and 2, the acetyl and trifluoracetyl derivatives of the former, and the reduction products thereof have no significant anticoccidial activity.

Maternal leucocyte zinc deficiency at start of third trimester as a predictor of fetal growth retardation

Leucocyte zinc concentrations were measured in 70 mothers at the beginning of the third trimester of pregnancy and compared with the weight centiles of their subsequently delivered babies. The median maternal leucocyte zinc concentrations rose progressively with weight centile. Thus the median leucocyte zinc concentration of the mothers delivering babies weighing below the 10th centile was 112 nmol/10(9) leucocytes and that of the mothers with babies weighing above the 90th centile was 229.5 nmol/10(9) leucocytes. A maternal leucocyte zinc concentration less than 120 nmol/10(9) leucocytes strongly predicted a baby weighing below the 10th centile (positive predictive value = 71.9%, negative predictive value = 91.5%, sensitivity = 64.3%, specificity = 81.8%). These findings suggest that maternal zinc concentration might have a role in antenatal screening, but larger studies are required.

Prediction of Hysteresis Properties from Reticulation Studies of Carbon Black Suspensions in Mineral Oil

1. A linear log-log relationship was observed both for specific conductivity-time and viscosity-shear rate of carbon black suspensions in liquid vehicles. The slope, n, is related to the rate of recombination of carbon black aggregates, while the intercept (ρ0) is a measure of specific conductivity of carbon blacks after one minute recombination. 2. The reformation rate index, n, varies inversely with the surface area of the blacks. 3. The hysteresis relationship for suspensions (ρ0×1/n), correlates with hysteresis properties in a solid rubber. 4. Thus, hysteresis properties of black loaded elastomers can be predicted from reticulation studies of carbon black suspensions in liquid vehicles.

Characterization of atrial fibrillation in man: studies following open heart surgery

The nature of localized atrial activation during atrial fibrillation was characterized in 34 patients following open heart surgery. Bipolar atrial electrograms (AEG) recorded in each patient with atrial fibrillation exhibited a myriad of sizes, shapes, polarities, amplitudes, and beat-to-beat intervals. On the basis of the AEG morphology and the nature of its baseline, we have classified the recordings into four Types. Type I was characterized by discrete AEG complexes separated by an isoelectric baseline free of perturbation, Type II by discrete AEG complexes but with perturbations of the baseline between complexes, Type III by AEGs which failed to demonstrate either discrete complexes or isoelectric intervals, and Type IV in which AEGs of Type III alternated with periods characteristic of Type I and/or Type II. In 22 patients, the AEGs were recorded a second time, and in 11 of these patients the type of atrial fibrillation changed between the first and second recording period. An atrial flutter-fibrillation pattern in the ECG was associated with a relatively ordered atrial activation pattern and a relatively slow atrial rate. Human atrial fibrillation is not an electrophysiologically homogeneous process when compared among different patients or ad seriatim in the same patient.

Pulmonary arterial compression syndrome caused by false aneurysm of left ventricular outflow tract

A 29 year old man experienced exertional dyspnea and coughing 3 1/2 years after insertion of a Brauwald-Cutter aortic valve prosthesis. Clinical examination suggested pulmonary arterial hypertension, and cardiac catheterization revealed a saccular lesion apparently arising from the left ventricular outflow tract and producing compression of the right pulmonary artery. Origin from the left ventricular outflow tract just under the aortic ring was confirmed at operation. The lesion apparently arose from an anular excavation related to previous endocarditis with abscess formation. Reported cases of similar aneurysmal lesions are briefly reviewed, and other known causes of the pulmonary arterial compression syndrome are discussed.