Hyperacute rejection is attenuated in GalT knockout swine lungs perfused ex vivo with human blood.

BACKGROUND: Hyperacute rejection (HAR) is one of the principal obstacles to successful xenotransplantation. Homozygous alpha-1,3-galactosyltransferase knockout (GalT-KO) miniature swine now offer the prospect of overcoming this barrier to xenotransplantation. In this study, the short-term function of GalT-KO swine lungs was evaluated in a well-established ex vivo model of swine-to-human lung xenotransplantation. METHODS: Lungs from homozygous GalT-KO swine (n = 3) and control lungs from pigs of the background strain used to create the GalT-KO pig line (n = 2) were perfused ex vivo with freshly collected heparinized human blood. Graft function was assessed by various physiologic measurements, serial histologic and immunohistochemical evaluation, and assays of complement and platelet activation. RESULTS: Xenoperfused control swine lungs exhibited HAR with graft survival times <5 minutes. In contrast, GalT-KO swine lungs retained their function for approximately 2 hours, on average. GalT-KO swine lungs showed decreased complement and platelet activation compared with controls. Nonetheless, activation of complement and coagulation cascades was not completely eliminated in the GalT-KO swine lungs. CONCLUSIONS: The survival of xenoperfused GalT-KO swine lungs was significantly prolonged, as compared with control lungs expressing Gal. This appears to have been due largely to substantially reduced complement activation. Nonetheless, the xenoperfused GalT-KO lungs still showed some evidence of complement fixation and intravascular coagulopathy by the time of graft demise.

Hypodipsic hypernatremia and diabetes insipidus following anterior communicating artery aneurysm clipping: diagnostic and therapeutic challenges in the amnestic rehabilitation patient.

Hypodipsic hypernatremia (HH) represents a pathological increase in serum sodium due to a lack of thirst and defect in hypothalamic osmoreceptors. While 15% of patients with HH have a vascular aetiology, few cases have been described. Moreover, the presence of such abnormalities in the amnestic patient can have particularly threatening implications, as HH tends to recur unless the patient complies with a regimen of water intake. This study reports the case of a 46-year-old male admitted for rehabilitation of functional deficits following subarachnoid haemorrhage (SAH), with clipping of an anterior communicating artery (ACoA) aneurysm. Clinical examination was remarkable for profound short-term memory loss and inability to retain new information. Blood chemistry on admission showed a serum sodium level of 160 mEq/L, increasing to 167 mEq/L the following day. The patient denied thirst, and showed no clinical signs of dehydration. Neuroendocrine evaluation revealed diabetes insipidus (DI) and HH. Treatment initially included DDAVP and intravenous hydration, later supplemented with chlorpropramide. Stabilization of serum sodium and osmolality did not ensue until the treatment regimen included hydrochlorothiazide and supervision of enforced fluid intake. Endocrine abnormalities may be encountered among patients with vascular lesions adjacent to the hypothalamus. Rehabilitation interventions include establishing a structured medication regimen with fluid administration in the amnestic patient with hypothalamic dysfunction.

An adenosine A2A agonist, ATL-146e, reduces paralysis and apoptosis during rabbit spinal cord reperfusion.

BACKGROUND: We hypothesized that systemic ATL-146e, an adenosine A(2A) agonist, would decrease spinal cord reperfusion inflammatory stress and inhibit apoptosis and that these effects would correlate with improved neurologic functional outcome. METHODS: Thirty rabbits underwent cross-clamping of the infrarenal aorta for 45 minutes. One group of animals (n = 14) received 0.06 microg/kg per minute of ATL-146e infused intravenously for 3 hours, beginning 15 minutes before reperfusion. A second group of animals (n = 16) underwent spinal cord ischemia with saline vehicle alone and served as ischemic controls. Animals (n = 9, 11) from each group survived for 48 hours and assessed for neurologic impairment with the Tarlov (0-5) scoring system. Four animals from each group were humanely killed at the end of the 3-hour treatment period, and the remainder killed after 48 hours' survival. In all animals, lumbar spinal cord tissue specimens were frozen for subsequent Western blot analysis of heat shock protein 70 (HSP 70), and for the p85 fragment of poly (ADP-ribose) polymerase (PARP). Neuronal viability indices were determined at 48 hours with hematoxylin and eosin staining. RESULTS: There was improvement in neurologic function in rabbits receiving ATL-146e (P <.001) compared with ischemic controls. At the end of the 3-hour treatment period there was a 46% (P <.05) decrease in HSP 70 expression in the ATL-146e group compared with the control group, but no difference in PARP expression. At 48 hours, there was no difference between control and ATL-146e groups in HSP 70 expression, but there was a 65% (P <.05) reduction in PARP in the spinal cords of animals that had received ATL-146e. There was a significant improvement in neuronal viability indices in animals receiving ATL-146e compared with ischemic controls (P <.05). CONCLUSIONS: Systemic ATL-146e infusion during reperfusion after spinal cord ischemia results in preservation of hindlimb motor function. There is evidence of decreased spinal cord inflammatory stress immediately after treatment with ATL-146e as indicated by reduced HSP 70 induction. Treatment with ATL-146e is associated with a reduction in neuronal apoptosis as suggested by a substantial decrease in the fragmentation of PARP at 48 hours. These results suggest that inflammation during reperfusion and subsequent apoptosis contribute to paralysis after restoration of blood flow to the ischemic spinal cord.

Extended-release nifedipine bezoar identified one year after discontinuation.

OBJECTIVE: To report a case of tablet impaction of nifedipine extended-release tablets (Procardia XL) discovered one year after discontinuation of the drug in a patient with peptic stricture. DATA SOURCES: English-language references identified via a MEDLINE search from 1966 through September 1998 and bibliographic review of pertinent articles. DATA SYNTHESIS: Extended-release nifedipine has been associated with the formation of medication bezoars in case reports. Bezoars are concretions of undigested material within the gastrointestinal (GI) tract. Although they can occur throughout the GI tract, bezoars are most frequently located in the stomach and, rarely, in the duodenum. We report an unusual case of tablet impaction with a gastric outlet obstruction in the duodenal area discovered one year after the patient stopped taking extended-release nifedipine. CONCLUSIONS: Extended-release nifedipine is associated with tablet impaction, even long after discontinuing administration. Although rare, clinicians should be aware of this potential problem when prescribing extended-release medications to patients at risk, and should consider this possible etiology when refractory epigastric pain and weight loss occur.

Effects of COER-verapamil on circadian pattern of forearm vascular resistance and blood pressure.

Controlled-onset extended-release verapamil (COER-V) is designed so drug concentrations rise sharply in the early morning to coincide with the peak incidence of cardiovascular events. The primary objective of this study was to compare the diurnal pattern of forearm vascular resistance (FVR) between hypertensives and normotensives and to determine the effect of COER-V on FVR's diurnal pattern. The authors also studied the effects of COER-V on 24-hour ambulatory blood pressure (ABP) and the early morning blood pressure rise. Baseline 24-hour ABP was recorded, and FVR was determined by venous occlusion plethysmography at 7 a.m., 2 p.m., and 9 p.m. in 23 untreated hypertensives; FVR was also determined in 10 matched, normotensive controls. Plethysmography studies and 24-hour ABP were repeated and S- and R-verapamil concentrations determined over 24 hours by HPLC following > or = 4 weeks of therapy. The diurnal pattern of FVR differed between hypertensives and normotensives, with normotensives exhibiting an FVR decline between 2 p.m. and 9 p.m., while FVR rose at 9 p.m. in hypertensives. COER-V appeared to minimize the diurnal variation in FVR in hypertensives, although there were no significant differences at any single time point (baseline 7 a.m.: 58 +/- 24; 2 p.m.: 48 +/- 13; and 9 p.m.: 55 +/- 19 vs. COER-V at 7 a.m.: 51 +/- 23; 2 p.m.: 51 +/- 17; and 9 p.m.: 54 +/- 17 mmHg/ml/min/100 g). COER-V effectively reduced ABP throughout the 24-hour period (p < 0.05). No significant differences were found in the slopes of the early morning rise in BP or change in morning trough-to-peak BP at baseline and on the drug. The data suggest that hypertension alters the normal diurnal pattern in FVR and that COER-V minimizes the diurnal variation in this parameter. In addition, the authors conclude that COER-V is an effective antihypertensive that lowers BP throughout a 24-hour period, but it does not blunt the early morning rate of BP rise despite peak S-verapamil concentrations in the early morning.

Focal nodular hyperplasia of the liver: a comprehensive pathologic study of 305 lesions and recognition of new histologic forms.

Atypical histologic variants of focal nodular hyperplasia have been reported and are sometimes difficult to recognize. To characterize the morphologic spectrum of focal nodular hyperplasia, we studied 305 lesions surgically resected from 168 patients. Clinicomorphologic correlations were established by statistical analyses. The patients included 150 women and 18 men (sex ratio, 8:1; median age, 38 years). One hundred twenty-eight (76.2%) patients had solitary lesions, and 40 (23.8%) had 2 to 30 lesions. All 305 lesions measured 1 mm to 19 cm in diameter. Only 49% of these lesions had one to three macroscopic scars. Histologically, 245 (80.3%) lesions were of classical form, and 60 (19.7%) lesions were nonclassical. The latter were classified as focal nodular hyperplasia of telangiectatic form (47 lesions), of mixed hyperplastic and adenomatous form (five lesions), and with atypia of large cell type (eight lesions). Several benign or malignant tumors were found in association with these lesions. This large retrospective series of focal nodular hyperplasia shows the relative incidence of its classical and nonclassical forms. The absence of a central scar could explain the difficult preoperative diagnosis of some of the cases. The morphologic diagnostic criteria in this study require further prospective evaluation.

Analysis of cell surface properties using derivatized agarose beads.

An assay has been developed to analyse cell surface properties using agarose beads derivatized with amino acids, sugars, proteins, and other molecules. The assay is simple and rapid and is useful to identify new cell surface markers. Various species and strains of yeast, paramecium, and Euglena were tested for their ability to bind to over 100 types of derivatized beads. A variety of specificity studies were performed in order to understand the nature of cell-bead binding. Our results indicate that cell-bead binding is often specific enough to distinguish between configurational isomers and spacer sizes and can be blocked by addition of specific molecules to the incubation medium. In some cases, different species or strains differed only by their binding to a single bead type. This simple and rapid assay may help to uncover new cell surface receptors and may lead to the development of clinically useful compounds for therapeutic applications.

Efficacy and effectiveness of five day treatment of uncomplicated falciparum with artemisinin or artesunate in Vietnam.

A study on efficacy and effectiveness of artemisinin (total dose of 60 mg/kg) and artesunate (total dose of 12 mg/kg over five days) in treatment of uncomplicated malaria was conducted in highly malaria transmitted areas in Vietnam. 126 uncomplicated malaria cases finished 14 day follow-up. 100% cure rate achieved at day 14 in patients of the efficacy groups received either artemisinin or artesunate, while it was 83% and 93% in patients treated respectively with artemisinin and artesunate of the effectiveness groups. Compliance of the treatment regimens was discussed.

The effects of diminishing albumin binding to some Endothelin receptor antagonists.

As a pharmacological class, Endothelin-A receptor (ET(A)) antagonists are highly bound (>98%) to serum albumin. In the presence of physiological concentrations of albumin, their affinities for ET(A) decrease 10 to 100 fold. We have prepared ET(A) antagonists which exhibit lower degrees of binding to albumin, while maintaining potency and selectivity for the ET(A) receptor. The protein induced IC50 shift is reduced or eliminated in this new series of compounds. The compounds also display altered in vivo and pharmacokinetic profiles which may be consistent with their lower degree of protein binding.

The role of endothelin in heart failure and hypertension.

The endothelin family consists of three structurally similar isopeptides: ET-1, ET-2, and ET-3. The two receptor subtypes, ETA and ETB, have different receptor affinities for the isopeptides. Stimulation of ETA and ETB receptors results in vasoconstriction, and ETB stimulation also causes vasodilation. These receptors may have profound impact on the etiologies of various diseases, including heart failure and hypertension. Studies with endothelin-receptor antagonists in animals and humans with heart failure show promising short- and long-term results. The place of the agents in the treatment of essential hypertension remains controversial, but they may have a greater role in hypertensive blacks and transplant recipients.

Diamino acid derivatives of porphyrins penetrate into yeast cells, induce photodamage, but have no mutagenic effect.

The yeast Saccharomyces cerevisiae was used as a model eukaryotic organism to study the uptake of diamino acid derivatives of porphyrins and their phototoxicity with particular emphasis on possible mutagenic effects. The water-soluble hematoporphyrin derivatives diarginate (HpD[Arg]2) and 1-arginin di(N-amino acid)-protoporphyrinate used in this study are effective photosensitizers in tumor photodynamic therapy. Depending on the amino acid substituent, the porphyrin derivatives differ in their affinity for yeast cells. It is shown that HpD(Arg)2 and PP(Met)2 (Arg)2 penetrate into the yeast cell and are metabolized. Both compounds sensitize yeast cells to photodamage but have no mutagenic effect on nuclear or mitochondrial genomes.

Saccharomyces cerevisiae mutants defective in heme biosynthesis as a tool for studying the mechanism of phototoxicity of porphyrins.

Mutants of Saccharomyces cerevisiae accumulating uroporphyrin (UP) or protoporphyrin (PP) were used as a model for the in vivo phototoxic effect of porphyrins observed in the human skin photosensitivity associated with porphyrias (porphyria cutanea tarda and erythropoietic protoporphyria). We have found that UP is localized in vacuoles and PP is present in all compartments except vacuoles in yeast cells. Endogenous PP is much more effective as a photosensitizer of yeast cells than UP. Protoporphyrin action is strictly dependent on the presence of oxygen. In contrast, UP displays a phototoxic effect even if oxygen is not present in the suspension, implicating a free radical mechanism that operates in anaerobiosis upon photosensitization by UP. Catalase or superoxide dismutase deficiency affects photosensitization by UP. A possible mechanism of UP photosensitizing activity is discussed.

High potency neuroleptics and violence in schizophrenics.

In a controlled study, inpatient violence was measured during placebo, high-potency (haloperidol) and low-potency (chlorpromazine or clozapine) neuroleptics. Some patients had a marked increase in violent behavior with the moderately high-dose haloperidol, but not with low-potency neuroleptics. The authors discuss reasons for the increased violence with haloperidol, including akathisia and drug-induced behavioral toxicity.