Sustained membrane depolarization and pulmonary artery smooth muscle cell proliferation

Pulmonary vasoconstriction and vascular medial hypertrophy greatly contribute to the elevated pulmonary vascular resistance in patients with pulmonary hypertension. A rise in cytosolic free Ca(2+) ([Ca(2+)](cyt)) in pulmonary artery smooth muscle cells (PASMC) triggers vasoconstriction and stimulates cell growth. Membrane potential (E(m)) regulates [Ca(2+)](cyt) by governing Ca(2+) influx through voltage-dependent Ca(2+) channels. Thus intracellular Ca(2+) may serve as a shared signal transduction element that leads to pulmonary vasoconstriction and vascular remodeling. In PASMC, activity of voltage-gated K(+) (Kv) channels regulates resting E(m). In this study, we investigated whether changes of Kv currents [I(K(V))], E(m), and [Ca(2+)](cyt) affect cell growth by comparing these parameters in proliferating and growth-arrested PASMC. Serum deprivation induced growth arrest of PASMC, whereas chelation of extracellular Ca(2+) abolished PASMC growth. Resting [Ca(2+)](cyt) was significantly higher, and resting E(m) was more depolarized, in proliferating PASMC than in growth-arrested cells. Consistently, whole cell I(K(V)) was significantly attenuated in PASMC during proliferation. Furthermore, E(m) depolarization significantly increased resting [Ca(2+)](cyt) and augmented agonist-mediated rises in [Ca(2+)](cyt) in the absence of extracellular Ca(2+). These results demonstrate that reduced I(K(V)), depolarized E(m), and elevated [Ca(2+)](cyt) may play a critical role in stimulating PASMC proliferation. Pulmonary vascular medial hypertrophy in patients with pulmonary hypertension may be partly caused by a membrane depolarization-mediated increase in [Ca(2+)](cyt) in PASMC.

"High probability" perfusion lung scans in pulmonary venoocclusive disease

"High-probability" ventilation/perfusion (V/Q) lung scans generally indicate proximal pulmonary arterial occlusion by thromboemboli or, rarely, other processes such as tumors, fibrosing mediastinitis, or vasculitis. In this report we describe three patients with high probability V/Q scans in whom pulmonary angiography failed to demonstrate arterial occlusion. All three patients were determined to have pulmonary venoocclusive disease (PVOD). In two patients, a tissue diagnosis of PVOD was made, in one case with explanted tissue taken after a successful heart-lung transplant and in the other case with tissue taken at autopsy. PVOD in the third patient was diagnosed with pulmonary venography. A potential explanation for the discrepancy between perfusion lung scan and pulmonary angiographic findings in PVOD is discussed.

The malignant potential of small cystic ovarian tumors in women over 50 years of age

OBJECTIVE

The aim of this study was to determine the risk of malignancy in cystic ovarian tumors < 10 cm in diameter in asymptomatic postmenopausal women or women >or =50 years of age.

METHODS

All cystic ovarian tumors detected by transvaginal sonography screening in asymptomatic postmenopausal women or women > or =50 years of age were evaluated with respect to size and morphology. Histology was recorded on all tumors removed surgically. Follow-up data were available both on patients undergoing surgery and on those who elected to be followed without operative intervention.

RESULTS

Unilocular cystic tumors were detected in 256 of 7705 patients (3.3%). All tumors were < 10 cm in diameter and 90% were < 5 cm in diameter. One hundred twenty-five of these cysts (49%) resolved spontaneously within 60 days and 131 (51%) persisted. Forty-five patients with persisting ovarian cysts underwent operative removal of these tumors. Thirty-two patients had ovarian serous cystadenomas, and the remainder had a variety of benign lesions. There were no cases of ovarian carcinoma in this group. Eighty-six patients with unilocular cystic ovarian tumors were followed at 3- to 6-month intervals without surgery, and none have developed ovarian cancer. Complex cystic ovarian tumors were detected in 250 patients (3.2%). All tumors were < 10 cm in diameter and 89% were < 5 cm in diameter. One hundred thirty-five (55%) resolved spontaneously within 60 days, and 115 (45%) persisted. One hundred fourteen of these patients underwent operative tumor removal. Seven patients had ovarian carcinoma, 1 had primary peritoneal cancer, and 1 had metastatic breast cancer to the ovary.

CONCLUSION

Unilocular ovarian cysts < 10 cm in diameter in asymptomatic postmenopausal women or women > or =50 years of age are associated with minimal risk for ovarian cancer. In contrast, complex ovarian cysts with wall abnormalities or solid areas are associated with a significant risk for malignancy. These data are important in determining optimal strategies for operative intervention in these patients.

Lymph node metastases and prognosis in patients with stage IA2 cervical cancer

Ninety-four patients with squamous cell carcinoma invading the cervical stroma to a depth of >3.0-5.0 mm with 7 mm or less in horizontal spread (FIGO Stage IA2) were evaluated. Depth and lateral extent of stromal invasion were verified using an ocular micrometer. Cell type and lymph vascular space invasion (LVSI) were recorded in each case. Patients were treated primarily by radical hysterectomy with pelvic lymphadenectomy, and those with lymph node metastases were offered postoperative radiation. Following treatment, patients were seen at 3-month intervals for 2 years, and every 6 months thereafter. The mean duration of follow-up was 6.9 years (range 0.4-23.5 years). Seven of 94 patients (7.4%) had lymph node metastases. Five patients had 1 positive node, 1 patient had 2 positive nodes, and 1 patient had 3 positive nodes. Five patients developed recurrent cancer and 4 died of disease. LVSI was present in 31 cases (33%). Tumor recurrence was significantly increased in patients with positive LVSI (9.7% vs 3.2%). The 5-year survival rate of patients with LVSI was 89% vs 98% in patients without this finding (P = 0.058). The 5-year survival rate of all Stage IA2 cervical cancer patients was 95%. Patients with Stage IA2 cervical cancer have a significant risk of lymph node metastases and should be treated by radical hysterectomy with pelvic lymphadenectomy. LVSI is an important prognostic variable in these patients and should be recorded in all cases.

Nd:YAG laser excision of a giant gingival pyogenic granuloma of pregnancy

A 19-year-old Hispanic nullipara experienced the rapid growth of an oral lesion on the right lower gingiva which she had first noticed at 29 weeks gestation. The lesion interfered with oral hygiene and eating. At surgery, the lesion measured 3.5 x 2.5 x 2.0 cm. Biopsy confirmed a pyogenic granuloma ("granuloma gravidarum"). Panorex films showed no bony invasion. The lesion was excised using the Nd:YAG laser under general anesthesia when the patient had reached 36 3/7 weeks gestation. We chose the Nd:YAG laser over the CO2 laser for the removal of this very vascular lesion, because of its superior coagulation characteristics. This technique results in removal of the lesion with less danger of bleeding than with any other surgical technique. The patient did well postoperatively, delivered a healthy 3,884 g infant at 40 6/7 weeks gestation, and has had no recurrence after 15 months of follow-up.

Primary breast cancer of the vulva

Supernumerary breasts on the vulva are a rare occurrence. There have been 26 cases previously reported and only 4 case reports of primary mammary carcinoma of the vulva. This is the fifth case report of mammary carcinoma of the vulva and the second report using tamoxifen for adjuvant treatment.

Management of advanced juvenile granulosa cell tumor of the ovary

Juvenile granulosa cell tumor of the ovary occurs most frequently in young women and children. Ten percent of cases present during pregnancy. The majority of tumors are in FIGO Stage I and have a favorable prognosis. The prognosis of higher stage tumors, however, is generally less favorable. We report the long-term, disease-free survival of a patient with FIGO Stage III juvenile granulosa cell tumor of the ovary. We believe this to be the first report of a successful pregnancy following "MAC" chemotherapy for this particular malignancy.

An immunocytochemical study of the distribution of Rift Valley fever virus in the mosquito Culex pipiens

The dissemination of Rift Valley fever (RVF) virus in females of the epidemic vector Culex pipiens was studied immunocytochemically. Among orally infected specimens, viral antigen was detected in all major midgut regions, although individuals varied with respect to which regions were infected. Among specimens with disseminated infections (infections beyond the midgut epithelium), antigen was detected in most tissues, including those of the nervous and endocrine systems. However, no antigen was found in the ovarian follicular epithelia, oocytes/nurse cells, or female accessory gland. A viral dissemination index (DI) based on several tissues was determined for each orally infected specimen and used to estimate the extent of viral dissemination in the hemocoel. Plots of DI values as a function of time after ingestion of an infectious blood meal indicated that dissemination was sporadic, and that once virus escapes from the midgut, its spread to other tissues is rapid. The most common sequence of tissue/organ infection following escape of virus from the midgut epithelium appears to be as follows: intussuscepted foregut, fat body, salivary glands and thoracic ganglia, epidermis, and ommatidia of the compound eyes. Reduced fecundity and survival identified in other studies of RVF virus-infected Cx. pipiens are probably explainable on the basis of extensive tissue and organ infection resulting in an overall energy drain. Infection of regulatory tissues and organs such as the ganglia of the central nervous system, neurosecretory cells, and the corpora allata may also have detrimental effects on the overall functioning of a mosquito, even in the absence of widespread infection.

Transstadial and horizontal transmission of Rift Valley fever virus in Hyalomma truncatum

We exposed Hyalomma truncatum and Rhipicephalus appendiculatus to Rift Valley fever (RVF) virus in order to assess the possible role of these ticks as enzootic/epizootic RVF vectors. The virus replicated in H. truncatum after intracoelomic inoculation, and a minimum transmission rate of 17% was achieved after 15 days intrinsic incubation. The virus persisted at least 58 days in these ticks. Virus was also shown to pass transstadially from inoculated H. truncatum nymphs to adults, with peak viral titers reaching 10(3.5) plaque-forming units (PFU) in adult males after they were provided with bloodmeals. Virus was recovered from adult females 121 days after they were inoculated as nymphs. Viral titers peaked in inoculated male ticks after dropping off a host (mean titer = 10(4.3) PFU). RVF virus was not detected in pools of eggs and larval progeny from 11 infected female H. truncatum. H. truncatum larvae and nymphs did not become infected after ingesting greater than 10(2.0) PFU while feeding on a RVF viremic hamster. The number of infected specimens declined rapidly after RVF virus was inoculated into R. appendiculatus adults, and virus was undetectable 12 days post-inoculation.

Ingestion of immune bloodmeals and infection of Aedes fowleri, Aedes mcintoshi, and Culex pipiens with Rift Valley fever virus

Rift Valley fever (RVF) virus infection, dissemination, and transmission rates were determined for Aedes fowleri, Aedes mcintoshi and Culex pipiens 7 or 10 days after sequentially feeding to repletion on RVF virus immune hamsters and RVF viremic hamsters, or after feeding on a mixture of RVF virus immune sheep serum and RVF viremic hamster blood through a pledget. No significant differences in infection or dissemination rates were detected among Ae. fowleri and Cx. pipiens feeding to repletion on immune hamsters before or after feeding to repletion on a viremic hamster. Similarly, no significant differences in infection, dissemination, or transmission rates were observed among Ae. fowleri and Cx. pipiens feeding to repletion on immune hamsters or nonimmune (control) hamsters 0 or 24 hr after inoculation with RVF virus. Infection rates were significantly higher for Ae. fowleri (56/66, 85%) and Cx. pipiens (123/148, 83%) fed only on viremic hamsters than for those interrupted to complete feeding on an immune hamster (Ae. fowleri [24/49, 59%], Cx. pipiens [66/131, 50%]) or a nonimmune hamster (Ae. fowleri [32/51, 63%], Cx. pipiens [69/127, 54%]). However, no significant differences were detected in infection, dissemination, or transmission rates among Ae. fowleri, Ae. mcintoshi or Cx. pipiens fed on a viremic hamster and interrupted to complete feeding on an immune vs. a nonimmune hamster. Results from interrupted feeding experiments were significantly different from pledget feeding experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental infection of six species of ixodid ticks with Dugbe virus (family Bunyaviridae, genus Nairovirus)

The vector potential of each of 6 species of colonized North American and African ixodid ticks was assessed by intracoelomic inoculation with Dugbe virus (IbAr 1792, 14th passage in suckling mouse brain) and viral titers were monitored after selected incubation periods. Persistence of Dugbe virus for greater than or equal to 53 days in 5 species (Dermacentor andersoni, D. variabilis, Amblyomma americanum, Rhipicephalus appendiculatus, and R. sanguineus) indicates that infection occurred. Viral titers were significantly higher in female vs. male D. variabilis, R. appendiculatus, and A. americanum after blood feeding. Blood feeding had no significant effect on the viral titers of either female or male R. sanguineus. D. andersoni males also exhibited no significant change in viral titers after blood-feeding, but 100% (20/20) of drop-off females and 96% (24/25) of post-oviposition females (36 days postinoculation) contained no detectable virus even though virus was still found in unfed specimens less than or equal to 124 days postinoculation. Virus was not recovered from greater than 30,000 1st generation progeny (eggs, larvae, nymphs, adults) collected as eggs from inoculated female D. andersoni, D. variabilis, R. sanguineus, and R. appendiculatus 27-51 days postinoculation. R. sanguineus and R. appendiculatus transmitted Dugbe virus to guinea pigs when allowed to feed 1-3 weeks postinoculation.

Experimental transmission of Crimean-Congo hemorrhagic fever virus by Hyalomma truncatum Koch

Larval Hyalomma truncatum ticks were infected with Crimean-Congo hemorrhagic fever (CCHF) virus by allowing them to engorge on viremic newborn mice. The overall tick infection rate was 4.4% (24/542). Virus was detected in specimens for greater than or equal to 160 days postinfection. Transstadial transmission to the adult tick stage was observed and horizontal transmission to a mammalian host was demonstrated. Horizontal transmission of CCHF virus to uninfected adult ticks occurred while feeding with transstadially infected ticks on the same host. No evidence of transovarial virus transmission from infected female ticks to their 1st generation progeny was observed.

Experimental infection of Phlebotomus papatasi with sand fly fever Sicilian virus

Experimental studies were conducted to evaluate humans as hosts infecting the sand fly Phlebotomus papatasi with sand fly fever Sicilian (SFS) virus. Viral antigen and infectious virus circulated in the blood of infected volunteers on days 4 and 5 after intravenous inoculation with SFS virus. Viremia levels during the latter period were high enough to infect feeding sand flies, but only 13% (9/69) of the flies became infected. One out of every 3 infected sand flies that survived to feed a second time transmitted SFS to a hamster. These results confirm a vertebrate-sand fly-vertebrate transmission cycle for SFS virus, and demonstrate that horizontal transmission may contribute to the maintenance of this virus in nature.

The distribution of Rift Valley fever virus in the mosquito Culex pipiens as revealed by viral titration of dissected organs and tissues

Distribution of Rift Valley fever virus (RVFV) was studied in the mosquito Culex pipiens. Mosquitoes were dissected on days 1-7 after an infectious bloodmeal, and RVFV plaque assays were performed on the legs, posterior midgut, ovaries, salivary glands, thoracic ganglia, and remaining organs and tissues (remnants). On days 7-12 and 14 following an infectious bloodmeal, mosquitoes were tested for their ability to transmit virus and then dissected. Dissemination (systemic infection) rates averaged 22% on days 1-14 and transmission rates 33% on days 7-14. There were no significant differences in the viral titers of midgut samples among the nondisseminated infected (virus limited to alimentary canal), disseminated infected nontransmitting, and transmitting groups of mosquitoes. The sequence of infection of the organs and tissues studied appeared to be as follows: midgut, hemolymph, remnants: salivary glands, ovaries, and thoracic ganglia. Some individuals were found to have disseminated infections as early as 12 hr following an infectious bloodmeal. Trauma, simulated by vigorous shaking immediately following the viremic bloodmeal, did not affect either infection or dissemination rates.

Vector potential of selected North American mosquito species for Rift Valley fever virus

Selected North American mosquito species were evaluated as potential vectors of Rift Valley fever virus. Field populations of Aedes canadensis, Ae. cantator, Ae. excrucians, Ae. sollicitans, Ae. taeniorhynchus, Ae. triseriatus, Anopheles bradleyi-crucians, Culex salinarius, Cx. tarsalis, and Cx. territans perorally exposed to 10(6.2)-10(7.2) plaque forming units of Rift Valley fever virus readily became infected. Infection rates ranged from 51% (65/127) for Cx. salinarius to 96% (64/67) for Ae. canadensis. Disseminated infection rates were generally greater at 14 days than at 7 days after the infectious bloodmeal, and, with the exception of An. bradleyi-crucians, they were not significantly different than the pooled rate of 59% for each species tested. Only 5/55 (9%) of the An. bradleyi-crucians developed a disseminated infection. For most of the species, about half of the mosquitoes with a disseminated infection transmitted an infectious dose of virus to hamsters. While all species, with the exception of An. bradleyi-crucians, transmitted virus, Ae. canadensis, Ae. taeniorhynchus, and Cx. tarsalis had the highest vector potential of the species tested. Following inoculation of approximately 10(1.6) plaque forming units of virus, 100% of the mosquitoes of each species became infected. For most species, transmission rates were similar for inoculated individuals and those that developed a disseminated infection following peroral infection. Viral titers of transmitting and nontransmitting-disseminated individuals were similar for all species tested. These data suggest that, if Rift Valley fever virus was introduced into North America, several mosquito species would be capable of transmitting it.

Reduced survival of adult Culex pipiens infected with Rift Valley fever virus

The effect of Rift Valley fever (RVF) viral infection on the survival of female Culex pipiens was examined. In 3 experiments in which mosquitoes ingested RVF virus, there was a 44% decrease in survival to days 14-16 for transmitting vs. nontransmitting mosquitoes, and a 48% decrease in survival for individuals with disseminated vs. nondisseminated infections. These results were corroborated by other experiments in which survival of mosquitoes intrathoracically inoculated with RVF virus was compared with that of those inoculated with diluent. In both the per os and inoculation tests, uninfected mosquitoes survived significantly longer than infected mosquitoes. Even though mosquitoes with disseminated infections had a lower survival rate than did uninfected mosquitoes, dissemination and transmission rates were similar at days 7 and 14-18 after the infectious bloodmeal. This suggests that nondisseminated individuals were developing disseminated infections and becoming capable of transmitting virus between days 7 and 14-18 at approximately the same rate older transmitters were dying. The decreased survival associated with RVF viral infection should be considered in predictive models of this disease.

Routine methods in toxicology and therapeutic drug monitoring by high performance liquid chromatography. II. A rapid microscale method for determination of chloramphenicol in blood and cerebrospinal fluid

A highly sensitive, specific method for determining chloramphenicol levels in human blood plasma and cerebrospinal fluid is described. The method uses high performance liquid chromatography for the analysis, requires minimal quantities of patient specimen, and thus is suitable for use in newborn and pediatric patients. The method described in this article is specifically developed for routine use in laboratories engaged in therapeutic drug monitoring. It has advantages over other methods because it is less time consuming and can be used with commercially available controls.

Increased dissemination of dengue 2 virus in Aedes aegypti associated with concurrent ingestion of microfilariae of Brugia malayi

We investigated whether concurrent ingestion of dengue 2 virus and microfilariae of Brugia malayi would increase viral infection and dissemination rates in Aedes aegypti. Infection rates were similar in mosquitoes that ingested virus alone or both virus and microfilariae concurrently. However, viral dissemination rates, as determined by recovery of dengue virus from both legs and bodies separately, were significantly greater in mosquitoes that ingested both agents concurrently than in those that ingested virus alone. This study confirms that vectorial capacity of a natural vector of an arbovirus may be enhanced by the concurrent ingestion of microfilariae.

Detection of Rift Valley fever viral activity in Kenya by satellite remote sensing imagery

Data from the advanced very high resolution radiometer on board the National Oceanic and Atmospheric Administration's polar-orbiting meteorological satellites have been used to infer ecological parameters associated with Rift Valley fever (RVF) viral activity in Kenya. An indicator of potential viral activity was produced from satellite data for two different ecological regions in Kenya, where RVF is enzootic. The correlation between the satellite-derived green vegetation index and the ecological parameters associated with RVF virus suggested that satellite data may become a forecasting tool for RVF in Kenya and, perhaps, in other areas of sub-Saharan Africa.

Use of the avidin-biotin-peroxidase complex immunocytochemical procedure for detection of Rift Valley fever virus in paraffin sections of mosquitoes

The avidin-biotin-peroxidase complex (ABC) immunocytochemical procedure was used to locate Rift Valley fever (RVF) virus antigen in infected Aedes albopictus C6/36 cultured cells and in serial paraffin sections of intrathoracically-injected Egyptian Culex pipiens. Fixation of the cultured cells in formaldehyde or periodate-lysine-paraformaldehyde, and fixation of whole mosquitoes with formaldehyde resulted in good preservation of morphology and excellent differential staining between uninfected and infected specimens. Two primary antibodies against RVF virus were tested on the cultured cells: a polyclonal rabbit antiserum and a mixture of mouse monoclonal antibodies. Only the mouse monoclonal antibody mixture was tested on the Cx. pipiens. Specific staining of tissues in paraffin sections occurred at dilutions as high as 1:5,000. In both cultured Ae. albopictus cells and sections of Cx. pipiens, only the cytoplasm was positive for antigen. A preliminary list of tissues in Cx. pipiens that exhibited specific or nonspecific staining is given.

Enhanced mosquito blood-finding success on parasitemic hosts: evidence for vector-parasite mutualism

The generalized hematopathology frequently found in animals infected with vector-borne pathogens may maximize transmission by enhancing the ability of vectors to locate blood in infected hosts. We tested this idea of mutualism between parasite and vector by comparing duration of probing of mosquitoes feeding on noninfected and on malaria-(Plasmodium chabaudi) or arbovirus-(Rift Valley fever virus) infected animals. We found that median duration of probing (blood location) on infected rodents was reduced by at least 1 min as compared to noninfected rodents. This enhanced ability of vectors to locate blood, possibly caused by parasite-disrupted hemostasis, may be a common feature of vector-borne diseases.

Effect of extrinsic incubation temperature on the ability of Aedes taeniorhynchus and Culex pipiens to transmit Rift Valley fever virus

Studies were conducted to examine the effects of extrinsic incubation (EI) temperature on the vector competence of Egyptian Culex pipiens and North American Aedes taeniorhynchus for Rift Valley fever (RVF) virus. Following per os exposure, infection rates in Ae. taeniorhynchus remained relatively constant at 55%, 56%, and 59% for mosquitoes held at EI temperatures of 13, 26, and 33 degrees C, respectively. In contrast, significantly fewer Cx. pipiens became infected when held at 13 degrees C (38%), than when held at 26 degrees C (75%) or 33 degrees C (91%). In both species, viral dissemination and transmission occurred earlier in mosquitoes held at high temperatures as compared to those held at low temperatures. Following EI at 26 or 33 degrees C, Cx. pipiens were able to transmit virus as early as 1 day after inoculation with RVF virus. However, 3 days were required before the first transmissions by inoculated Ae. taeniorhynchus. Temperature of EI affected these 2 species differently in their ability to transmit RVF virus. Because of the importance of EI temperature on infection and transmission rates, as well the length of the EI period, the role of EI temperature will need to be evaluated for each virus and vector pair.

Rift Valley fever virus (family Bunyaviridae, genus Phlebovirus). Isolations from Diptera collected during an inter-epizootic period in Kenya

A total of 134 876 Diptera collected in Kenya during a 3-year period were tested in 3383 pools for Rift Valley fever (RVF) virus. Nineteen pools of unengorged mosquitoes were found positive for RVF. All isolations were made from specimens collected at or near the naturally or artificially flooded grassland depressions that serve as the developmental sites for the immature stages of many mosquito species. The isolation of virus from adult male and female A. lineatopennis which had been reared from field-collected larvae and pupae suggests that transovarial transmission of the virus occurs in this species.

Mechanical transmission of Rift Valley fever virus by hematophagous Diptera

Experimental studies were conducted to determine if hematophagous Diptera were capable of mechanical transmission of Rift Valley fever (RVF) virus to laboratory animals. All species tested (Glossina morsitans, Aedes aegypti, Aedes taeniorhynchus, Culex pipiens, Stomoxys calcitrans, Lutzomyia longipalpis, and Culicoides variipennis) mechanically transmitted the virus to hamsters. Mechanical transmission rates for G. morsitans ranged from 0-100%, with the probability of mechanical transmission positively correlated with initial viremia titer and negatively correlated with the time after virus exposure. Mechanical transmission of RVF virus to lambs was demonstrated with both G. morsitans and Cx. pipiens. These findings demonstrated that mechanical transmission of RVF virus by hematophagous flies may contribute to the natural transmission and dissemination of this virus.