Activation of neurokinin-1 receptors increases the excitability of Guinea pig dorsal root ganglion cells

The suppression of overactive bladder symptoms in patients and overactive bladder reflexes in animal models by neurokinin (NK)-1 receptor antagonists raises the possibility that these drugs target sensory neurons. This mechanism was evaluated by examining the interactions between a specific NK-1 agonist, [Sar(9),Met(O(2))(11)]-substance P (Sar-Met-SP), and a potent NK-1 antagonist, netupitant (NTP), on small size (20-30 μm) dissociated L6 and S1 dorsal root ganglion (DRG) neurons from female guinea pigs. Current-clamp recording revealed that Sar-Met-SP (1 μM) elicited membrane depolarization (average 8.05 ± 1.38 mV) in 27% (18 of 65) of DRG neurons. In 74% of the remaining neurons (35 of 47) Sar-Met-SP decreased the rheobase for action potential (AP) generation and increased the response to a suprathreshold stimulus (3 times rheobase) without changing the membrane potential. Sar-Met-SP also induced changes in the action potential (AP) wave form, including 1) an increase in overshoot (average 5 mV, n = 35 neurons), 2) a prolongation of AP duration (from 4.64 to 5.29 ms, n = 34), and 3) a reduction in the maximal rate of AP repolarization. NTP (200 nM) reversed the Sar-Met-SP-induced changes. Ca(2+) imaging showed that application of Sar-Met-SP (1 μM) decreased the tachyphylaxis induced by repeated application of capsaicin (0.5 μM), an effect blocked by pretreatment with NTP (200 nM). These results raise the possibility that activation of NK-1 receptors in primary sensory neurons plays a role in the generation of overactive bladder and that block of NK-1 receptors in these neurons may contribute to efficacy of NK-1 antagonists in the treatment of overactive bladder symptoms.     

Primary pulmonary hypertension: radiographic and scintigraphic patterns of histologic subtypes

The chest radiograph and perfusion lung scans were evaluated in 39 consecutive patients with primary pulmonary hypertension to see if these noninvasive methods could distinguish among the histologic subtypes. Chest radiographs were categorized as having either normal lung fields or increased bronchovascular markings. Blood flow on lung scans was graded as normal or as having diffuse, nonsegmental, patchy abnormalities. These patterns were then correlated against pathologic specimens obtained from 19 patients, which were graded on vascular changes and microthrombi. Plexogenic arteriopathy was characterized by a normal chest radiograph and normal distribution of tracer on lung scan. Thromboembolism was characterized by a normal chest radiograph but patchy distribution of tracer on lung scan. Pulmonary veno-occlusive disease was characterized by increased bronchovascular markings on chest radiograph as well as patchy distribution of tracer on lung scan. Distinguishing patients on the basis of their histologic characteristics may be important so that vasodilators or anticoagulants can be selected as therapy.     

Spontaneous regression of pulmonary leiomyomas during pregnancy.

Multiple pulmonary nodular densities simulating metastastic cancer were discovered in a routine chest roentgenogram of a 30-year-old pregnant woman. Lung biopsy revealed nodules composed of smooth muscle and collagenous tissue containing entrapped glandular elements. The lesions were initially interpreted as multiple pulmonary fibroleiomyomatous hamartomas (MPFLH). During pregnancy and the post-partum period, the pulmonary nodules regressed spontaneously. Critical analysis of the published cases as well as our own case indicates that multiple pulmonary fibroleiomyomatous hamartomas (MPFLH) cannot be distinguished from benign metastasizing leiomyoma (BML) by either clinical, roentgenographic, or pathologic criteria and that all represent pulmonary metastases from a primary uterine neoplasm. The spontaneous regression of the pulmonary nodules in the present case as well as the increased risk for development of progressive pulmonary insufficiency in the pre-menopausal patients indicates an apparent hormonal dependence. Total abdominal hysterectomy and bilateral salpingo-oophorectomy appears to be the treatment of choice.     

Muscle fiber orientation and connective tissue content in the hypertrophied human heart

To elucidate the structural correlates of cardiac failure in myocardial tissue, muscle fiber alignment and connective tissue volume fraction were measured at multiple sites in the left ventricular free wall and in the interventricular septum of 14 human hearts. Group 1 (five hearts; 280 +/- 20 gm.) had no evidence of cardiac disease, group 2 (five hearts; 380 +/- 30 gm.) had a history of systemic hypertension without clinical heart failure, and group 3 (four hearts;; 590 +/- 40 gm.) had both left ventricular overload and congestive failure. Fiber orientations were determined by measuring fiber angle relative to the circumferential direction (helix angle). The fraction of the myocardial volume occupied by connective tissue was determined by point counting. Our results indicate a smooth transition of helix angle from epi- to endocardial surface in the normal left ventricular free wall with nearly 55 per cent of the wall occupied by circumferentially oriented fibers near the cardiac equator (latitude of largest ventricular diameter); morphologically, the interventricular septum was nearly identical with the free wall. Fiber alignment was maintained in all three groups as was the fraction of wall occupied by circumferential fibers. Connective tissue volume fraction was, however, significantly increased (p less than 0.02) in hypertrophied hearts (groups 2 and 3) as compared with normal hearts, and at two of six sites in clinically failed hearts as compared with hypertrophied but functionally compensated hearts. Thus, muscle fiber orientation is not altered in the hypertrophied pressure-overloaded left ventricle, whereas connective tissue content is increased with the increase being greatest in the failing heart.     

Prolonged storage of tissues at low temperatures does not preclude their use for ultrastructural studies.

A cost-effective method for electron microscopic study of snap-frozen surgical specimens is described. The method is available to any surgical pathology laboratory equipped with a deep freezer and allows the performance of ultrastructural observations on archival material.     

Impaired virus-specific T cell responses in patients with myeloproliferative neoplasms treated with ruxolitinib

Ruxolitinib is effective in myeloproliferative neoplasms (MPN) but can cause reactivation of silent infections. We aimed at evaluating viral load and T-cell responses to human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) in a cohort of 25 MPN patients treated with ruxolitinib. EBV-DNA and HCMV-DNA were quantified monthly using real-time polimerase chain reaction (PCR) on peripheral blood samples, and T-cell subsets were analyzed by flowcytometry. HCMV and EBV-directed T-cell responses were evaluated using the IFN-γ ELISPOT assay. Most patients had CD4+ and/or CD8+ T-cells below the normal range; these reductions were related to the duration of ruxolitinib treatment. In fact, reduced T-lymphocytes' subsets were found in 93% of patients treated for ≥5 years and in 45% of those treated for <5 years (P = .021). The former also had lower median numbers of CD4+ and CD8+ cells. Subclinical reactivation of EBV and HCMV occurred in 76% and 8% of patients. We observed a trend to an inverse relationship between EBV and CMV-specific CD4+ and CD8+ T-cell responses and viral load, and a trend to an inverse correlation with ruxolitinib dose. Therefore, our data suggest that the ruxolitinib treatment may interfere with immunosurveillance against EBV and HCMV.