Defective proximal tubular fluid reabsorption in transgenic aquaporin-1 null mice

To investigate the role of aquaporin-1 (AQP1) water channels in proximal tubule function, in vitro proximal tubule microperfusion and in vivo micropuncture measurements were done on AQP1 knockout mice. The knockout mice were generated by targeted gene disruption and found previously to be unable to concentrate their urine in response to water deprivation. Unanesthetized knockout mice consumed 2.8-fold more fluid than wild-type mice and had lower urine osmolality (505 +/- 40 vs. 1081 +/- 68 milliosmolar). Transepithelial osmotic water permeability (Pf) in isolated microperfused S2 segments of proximal tubule from AQP1 knockout [-/-] mice was 0.033 +/- 0.005 cm/s (SE, n = 6 mice, 37 degreesC), much lower than that of 0.15 +/- 0.03 cm/s (n = 8) in tubules from wild-type [+/+] mice (P < 0.01). In the presence of isosmolar luminal perfusate and bath solutions, spontaneous fluid absorption rates (nl/min/mm tubule length) were 0.31 +/- 0.12 (-/-, n = 5) and 0.64 +/- 0.15 (+/+, n = 8). As determined by free-flow micropuncture, the ratios of tubular fluid-to-plasma concentrations of an impermeant marker TF/P in end proximal tubule fluid were 1.36 +/- 0. 05 (-/-, n = 8 mice [53 tubules]) and 1.95 +/- 0.09 (+/+, n = 7 mice [40 tubules]) (P < 0.001), corresponding to 26 +/- 3% [-/-] and 48 +/- 2% [+/+] absorption of the filtered fluid load. In collections of distal tubule fluid, TF/P were 2.8 +/- 0.3 [-/-] and 4.4 +/- 0.5 [+/+], corresponding to 62 +/- 4% [-/-] and 76 +/- 3% [+/+] absorption (P < 0.02). These data indicate that AQP1 deletion in mice results in decreased transepithelial proximal tubule water permeability and defective fluid absorption. Thus, the high water permeability in proximal tubule of wild-type mice is primarily transcellular, mediated by AQP1 water channels, and required for efficient near-isosmolar fluid absorption.     

Intravenous self-administration of ethanol in beta-endorphin-deficient mice

Extensive research on both human alcoholics and in animal models of alcoholism has implicated the release of endogenous opioids in the consumption of ethanol. Various experiments using opioid antagonists have indicated that these drugs cause both humans and animals to decrease their consumption of ethanol. However, it remains unclear exactly which of the endogenous opioids mediates the rewarding effects of ethanol. The present experiment used intravenous self-administration of ethanol to determine whether beta-endorphin (BE)-deficient mice differed from wild-type (WT) mice in ethanol self-administration. The BE-deficient mice completely lack BE, but are otherwise similar to the WT mice. By using intravenous self-administration, we were able to rule out any ability of BE to mediate differences in ethanol consumption via palatability factors alone. Both types of mice were 7 generations backcrossed onto a C57BL/6J inbred strain background. During nine daily, 2-hr free-operant sessions, 14 BE-deficient and 17 WT mice could nosepoke for 75 mg/kg ethanol infusions delivered intravenously on an fixed-ratio 3 schedule with a 2-sec time-out after each reinforcer delivery. Reinforcer delivery occurred following nosepokes in only one of two holes. Contrary to what was expected, BE-deficient mice acquired selective operant responding for ethanol, whereas WT mice did not. Although the two genotypes did not differ in either operant or locomotor behavior during the first session, by the end of the nine sessions, BE deficient mice were reliably nosepoking for ethanol, whereas WT mice were not. These findings may indicate that BE is not essential for the postingestive reinforcing effects of ethanol in these animals.     

Infectious clones and vectors derived from adeno-associated virus (AAV) serotypes other than AAV type 2

Adeno-associated viruses (AAVs) are single-stranded dependent parvoviruses being developed as transducing vectors. Although at least five serotypes exist (AAV types 1 to 5 [AAV1 to -5]), only AAV2, AAV3, and AAV4 have been sequenced, and the vectors in use were almost all derived from AAV2. Here we report the cloning and sequencing of a second AAV3 genome and a new AAV serotype designated AAV6 that is related to AAV1. AAV2, AAV3, and AAV6 were 82% identical at the nucleotide sequence level, and AAV4 was 75 to 78% identical to these AAVs. Significant sequence variation was noted in portions of the capsid proteins that presumably are responsible for serotype-specific functions. Vectors produced from AAV3 and AAV6 differed from AAV2 vectors in host range and serologic reactivity. The AAV3 and AAV6 vector serotypes were able to transduce cells in the presence of serum from animals previously exposed to AAV2 vectors. Our results suggest that vectors based on alternative AAV serotypes will have advantages over existing AAV2 vectors, including the transduction of different cell types, and resistance to neutralizing antibodies against AAV2. This could be especially important for gene therapy, as significant immunity against AAV2 exists in human populations and many protocols will likely require multiple vector doses.     

Substance P and related peptides in porcine cortex: whole tissue and nuclear localization

We experienced a case of a 60 year-old man with cardiac sympathetic denervation after aortic graft replacement of ascending aorta for a dissecting aneurysm (Debakey type II). Fourteen years after pheochromocytomectomy (paraganglioma), the patient developed a severe chest pain, and admitted to the hospital for the diagnosis of dissecting aneurysm. CT scan with contrast enhancement revealed thrombosed dissecting aneurysm in the region of ascending aorta to aortic arch. Graft replacement was undergone on the same day. 123I-MIBG imaging 20 days after the operation showed severely attenuated myocardial uptake (heart to mediastinum ratio 1.19), although the MIBG imaging before the operation showed normal myocardial uptake (heart to mediastinum ratio 1.55). Heart rate variability analysis in Holter ECG showed that the power of the low frequency (LF), that of the high frequency (HF) and L/H ratio were severely decreased. MIBG and heart rate variability analysis indicated that cardiac sympathetic and parasympathetic nerve were denervated. This is the first report of cardiac sympathetic denervation after aortic vascular surgery. Clinical significance of cardiac sympathetic denervation after aortic vascular surgery is uncertain, and further investigation will be required.     

Method to compare collision-induced dissociation spectra of peptides: potential for library searching and subtractive analysis

We report the development of a method to compare collision-induced dissociation (CID) spectra of peptides. This method employs a cross-correlation analysis of a CID spectrum to a reference spectrum and normalizes the cross-correlation score to the autocorrelation of the CID spectra. The query spectrum is compared by using both mass information and fragmentation patterns. Fragmentation patterns are compared to each other using a correlation function. To evaluate the specificity of the approach, a set of 2180 tandem mass spectra obtained from both triple-quadrupole tandem mass spectrometers (TSQ) and quadrupole ion trap mass spectrometers (LCQ) was created. Comparisons are performed between tandem mass spectra obtained on the same instrument type as well as between different instrument types. Accurate and reliable comparisons are demonstrated in both types of analyses. The scores obtained in the cross-comparison of TSQ and LCQ tandem mass spectra of the same peptide are found to be slightly lower than comparisons performed with spectra obtained on the same instrument type. The method appears insensitive to variations in day-to-day performance of the instrument, minor variations in fragment ion abundance, and instrumental differences inherent in the same instrument model. The use of this method of comparison is demonstrated for library searching and subtractive analysis of tandem mass spectra obtained during LC/MS/MS experiments.     

Health status and health care costs for publicly funded patients with schizophrenia started on clozapine

OBJECTIVE: The study examined the effect of clozapine treatment on the health care costs and health status of people with schizophrenia who are supported by public funds. METHODS: Thirty-three patients with schizophrenia hospitalized in a state facility were interviewed within one week of starting clozapine and six months later. Health status was assessed with four clinical rating scales measuring severity of psychopathology, negative symptoms, depression, and quality of life. Cost and health care utilization data were collected for the six months before and after initiation of clozapine. RESULTS: Only 52 percent of the subjects stayed on clozapine for six months. Subjects who continued on clozapine were more likely to be discharged within six months than those who did not continue. Six months after clozapine was started, health care costs showed a sayings of $11,464 per person, even after adjustment for pretreatment costs, and health status was improved. CONCLUSIONS: For subjects who continued on clozapine for six months, clozapine treatment was associated with reduced days of psychiatric hospital care, reduced overall costs despite increased outpatient treatment and residential costs, and improved health status.     

Epidural anesthesia and analgesia in the perioperative treatment of a patient with Kartagener syndrome

Kartagener's syndrome is an inherited disease characterized by a triad of symptoms--bronchiectasis, situs inversus and sinusitis--and is classified as an immotile cilia syndrome. Patients may experience specific airway problems when undergoing anesthesia for surgical procedures. We report the case of a woman with Kartagener's syndrome who underwent surgery under epidural anesthesia with postoperative epidural analgesia, both techniques proving successful.