Use of long RT-PCR to characterize splice variant mRNAs

Recent advances in long reverse transcription (RT)-PCR technology allow the copying of full-length coding regions of large mRNAs in one step. Using long RT-PCR, one can be certain that a given cDNA is derived from a single mRNA. In what to our knowledge is a novel application, we can isolate and characterize splice variants for any given mRNA in a systematic manner. We optimized long RT-PCR to copy the full-length coding region of human multidrug resistance (MDR1) mRNA or the major vault protein (MVP) mRNA in one step, so that only one full-length PCR product was synthesized in each case. Such stringent conditions are necessary to ensure that smaller than full-length products derived from total cell RNA are true splice variants. Twenty MDR1 double-stranded (ds) cDNAs, isolated from either the full-length or one prominent splice-variant DNA band, visualized on agarose gels, were cloned and sequenced. Two were full-length, wild-type in sequence as expected, and the rest were splice-variant mRNAs. Fourteen of the clones were identical and encoded a prominent splice-variant mRNA that can be detected in two tumor cell lines. This approach is shown to be generally applicable to the systematic analysis of splice-variant mRNAs derived from any gene.

Mechanism of action of the unusually potent microtubule inhibitor cryptophycin 1

Cryptophycin 1 is a remarkably potent antiproliferative compound that shows excellent antitumor activity against mammary, colon, and pancreatic adenocarcinomas in mouse xenographs. At picomolar concentrations, cryptophycin 1 blocks cells in the G2/M phase of the cell cycle by an apparent action on microtubules. The compound binds to tubulin, inhibits microtubule polymerization, and depolymerizes preformed microtubules in vitro. Its exceptionally powerful antitumor activity (many-fold greater than paclitaxel or the vinca alkaloids) raises important questions about its mechanism of action. By quantitative video microscopy, we examined the effects of cryptophycin 1 on the dynamics of individual microtubules assembled to steady state from bovine brain tubulin. At low nanomolar concentrations, in the absence of net microtubule depolymerization, cryptophycin 1 potently stabilized microtubule dynamics. It reduced the rate and extent of microtubule shortening and growing and increased the frequency of rescue. The results suggest that cryptophycin 1 exerts its antiproliferative and antimitotic activity by binding reversibly and with high affinity to the ends of microtubules, perhaps in the form of a tubulin-cryptophycin 1 complex, resulting in the most potent suppression of microtubule dynamics yet described.

Correlates of unmet need for mental health services by children and adolescents

BACKGROUND

Little is known about the extent and correlates of unmet need for mental health services in community samples of children and adolescents.

METHODS

Data were obtained from the 1285 parent/youth pairs interviewed at four sites in the USA and Puerto Rico in the Methods for the Epidemiology of Child and Adolescent Mental Disorders (MECA) Study. Unmet need was defined to exist if psychopathology and associated functional impairment were present but no mental health services had been received in the previous 6 months.

RESULTS

Of the total sample, 17.1% had unmet need. Adjusting for demographic variables, logistic regression analyses revealed that unmet need was significantly associated with: indicators of economic disadvantage, such as being on public assistance and not being covered by health insurance; opinions of the parents and children or adolescents that the latter had poor mental health; parental psychopathology; poor school grades; and parent-reported access barriers such as concern that the child would want to solve the problem unassisted, would refuse to attend mental health services, or would be hospitalized or taken away against the parent's will. No youth-reported access barriers were significantly associated with unmet need.

CONCLUSIONS

The economic correlates of unmet need may attain increased importance in the light of current reform in health care financing in the USA. Access may be facilitated by increasing parental knowledge of mental health services and enabling children and adolescents to initiate contact with services independently of their families.

Three new cryptophycins from Nostoc sp. GSV 224

Cryptophycin 46 (2), -175 (3), and -176(4) have been identified as three new trace constituents of Nostoc sp. GSV 224. Cryptophycin-46 is an epimer of cryptophycin-3 (5) and to date is the only naturally occurring analogue having the S configuration at C-10 (C-2 in Unit B). Cryptophycins-175 and -176 also differ in unit B where 3 is the O-methyl analogue of cryptophycin-45 (6) and 4 is the O-desmethyl analogue of cryptophycin-21 (8). The relative and absolute stereochemistries of the three new analogues have been related to known cryptophycins by synthesis.

Children's access to mental health care: does insurance matter?

Using data from a 1992 community survey of children and their parents (or guardians), we found major gaps in mental health insurance coverage. Interestingly, private insurance had no statistically significant effect on use of mental health services. Youth without insurance coverage and those with public insurance had higher rates of serious emotional disorder than did those with private insurance. The analysis is based on the National Institute of Mental Health's Methods for the Epidemiology of Child and Adolescent Mental Disorders (MECA) study, conducted in three mainland U.S. sites and in Puerto Rico.

Running hard and falling behind: a welfare analysis of two-earner families

"This paper investigates the commonly asserted proposition that long term economic changes have put the family in a financial bind. Structural parameters of a family utility model are obtained by estimating simultaneous labor supply functions for a two-earner household. We find evidence indicating that the average 1990s two-earner family would prefer to receive the 1980s real wage package (were it available) instead of the real wage package it actually faces. The degree to which the 1990s family is worse off (in terms of the changes in the real wage package) is roughly equivalent to an hour of leisure per week." The data are from the 1993 Current Population Survey and concern the United States.

Psychosocial characteristics of physically abused children and adolescents

OBJECTIVE

To examine the association between physical abuse and selected psychosocial measures in a community-based probability sample of children and adolescents.

METHOD

A sample of 9- through 17-year-olds (N = 665) and their caretakers in New York State and Puerto Rico were interviewed in the Methods for the Epidemiology of Child and Adolescent Mental Disorders (MECA) Study. Assessments included the Columbia Impairment Scale, the Instrumental and Social Competence Scale, the Diagnostic Interview Schedule for Children, the Peabody Picture Vocabulary Test, and questions regarding physical abuse. Regression analyses were conducted controlling for family income, family psychiatric history, perinatal problems, physical health, and sexual abuse.

RESULTS

A history of physical abuse was reported in 172 (25.9%) of the sample. It was significantly associated with global impairment, poor social competence, major depression, conduct disorder, oppositional defiant disorder, agoraphobia, overanxious disorder, and generalized anxiety disorder but not with suicidality, school grades, or receptive language ability.

CONCLUSION

A community probability sample of children and adolescents demonstrated significant associations between physical abuse and psychopathology, after controlling for potential confounders. This supports comprehensive screening for psychopathology among physically abused children and for physical abuse among those with psychopathology. Interventions aimed at improving social competence may be indicated.

Overview of the Fernald Dosimetry Reconstruction Project and source term estimates for 1951-1988

The Feed Materials Production Center, northwest of Cincinnati, processed uranium concentrates and uranium compounds recycled from other stages of nuclear weapons production, as well as some uranium ore and thorium. Particulate releases were primarily uranium (natural, depleted, and slightly enriched. In addition, two large silos containing radium-bearing residues were emission sources of radon and its decay products. The Fernald Dosimetry Reconstruction Project was undertaken to help the Centers for Disease Control and Prevention to evaluate the impact of the Feed Materials Production Center on the public from radionuclides released to the environment from 1951 through 1988. At this point in the study, the project has estimated the quantities of radioactive materials released to air, surface water, and in groundwater; developed the methodology to describe the environmental transport of the materials; developed mathematical models to calculate the resulting radiation doses; and evaluated environmental monitoring data to verify that the estimates of releases and transport are reasonable. Thorough review of historical records and extensive interaction with former and current employees and residents have been the foundation for reconstructing routine operations, documenting accidents, and evaluating unmonitored emission sources. The largest releases of uranium to air and water occurred in the 1950's and 1960's. Radon releases from the silos remained elevated through most of the 1970's. The quantity of uranium released to surface water was much less than that released to air. Best estimates of releases are reported as median values, with associated uncertainties calculated as an integral part of the estimates. Screening calculations showed that atmospheric pathways dominate the total dose from Feed Materials Production Center releases. Accordingly, the local meteorology, effluent particle size and chemical form, and wet and dry deposition, were particularly important in this study. The final goal of the project is the calculation of radiation doses to people living in the study domain, which is represented by a circle with radius of 10 km centered on the Feed Materials Production Center production area.

Dendroamides, new cyclic hexapeptides from a blue-green alga. Multidrug-resistance reversing activity of dendroamide A

Dendroamide A (1), one of three new bistratamide-type cyclic hexapeptides from the terrestrial blue-green alga (cyanobacterium) Stigonema dendroideum Fremy, exhibits multidrug-resistance reversing activity. The gross structures of the three compounds, dendroamides A-C, were determined by NMR and mass spectral analyses. Their absolute stereochemistries were determined by Marfey and chiral GC/MS analyses of derivatives formed from acid hydrolysis of the intact and ozonized peptides.

Infectious keratoconjunctivitis in free-ranging mule deer (Odocoileus hemionus) from Zion National Park, Utah

An epizootic of infectious keratoconjunctivitis (IK) was studied opportunistically in free-ranging mule deer (Odocoileus hemionus) from Zion National Park, Utah (USA), from November 1992 to March 1994. Moraxella sp. and Chlamydia sp. were isolated from the conjunctiva of two of seven deer. In addition, Thelazia californiensis occurred on the conjunctivas of six of seven deer. Based on field observations, adults appeared to be affected clinically at a higher incidence during both years as opposed to juveniles. Corneal opacity was the most apparent clinical sign from 1992 to 1993. However, in the following year, blepharospasm and epiphora were noted more often. We were also able to document the clinical recovery of three affected deer. In addition, Moraxella sp. was recovered from the eyes of a clinically unaffected deer 1 year after the epizootic occurred.

Preclinical anticancer activity of cryptophycin-8

Cryptophycin-8 was prepared by the conversion of the epoxide group on cryptophycin-1 to a chlorohydrin. In the studies reported here, cryptophycin-8 was evaluated for preclinical activity against subcutaneous tumors of both mouse and human origin. At the highest non-toxic single course treatment, the following results were obtained (Table A). Cryptophycin-8 was less potent than cryptophycin-1 by approximately 4-fold; however, it was both more water soluble and had greater therapeutic efficacy, as demonstrated by % T/C, tumor cell log kill values, range of dose effectiveness and host cures.

Cyclic peptides and depsipeptides from cyanobacteria: a review

An elaborate array of structurally-novel and biologically-active cyclic peptides and depsipeptides are found in blue-green algae (cyanobacteria). Several of these compounds possess structures that are similar to those of natural products from marine invertebrates. Most of these cyclic peptides and depsipeptides, such as the microcystins and the lyngbyatoxins, will probably only be useful as biochemical research tools. A few, however, have the potential for development into useful commercial products. For example, cryptophycin-1, a novel inhibitor of microtubule assembly from Nostoc sp GSV 224, shows impressive activity against a broad spectrum of solid tumors implanted in mice, including multidrug-resistant ones, and majusculamide C, a microfilament-depolymerizing agent from Lyngbya majuscula, shows potent fungicidal activity and may have use in the treatment of resistant fungal-induced diseases of domestic plants and agricultural crops.

Gossypol toxicity in preruminant calves

Twenty-four of 57 calves fed a diet containing 33% cotton seed meal (CSM) died between 7 and 15 weeks of age. Initial deaths were not accompanied by premonitory signs, but after CSM withdrawal most calves developed rough coats, anorexia, weakness, ascites and subcutaneous oedema. Those that died had large volumes of serous fluid in the body cavities, hard livers of 'nutmeg' appearance, and pulmonary congestion. Histopathologically the livers showed periacinar necrosis in acute cases and periacinar fibrosis in chronic cases. Lungs from several calves had oedema, haemosiderosis and fibrosis in some pulmonary vessels. Atrophy of myocardial fibres was present in most cases. The concentration of free gossypol in the diet was 100 to 220 mg/kg. Ante-mortem and post-mortem findings supported a diagnosis of gossypol poisoning. The deaths continued for 4 weeks after withdrawal of CSM from the diet.

Tubercidin stabilizes microtubules against vinblastine-induced depolymerization, a taxol-like effect

A sensitive assay for the detection of microtubule-stabilizing agents [1] was used to screen an extensive collection of cyanobacterial and microalgal extracts. The hydrophilic extract of the cyanobacterium, Plectonema radiosum (UH isolate IC-70-1), exhibited microtubule-stabilizing activity. Bioassay-directed purification of the active compound yielded tubercidin (7-deazaadenosine), a potent cytotoxic nucleoside analog. Further studies revealed that tubercidin protected a population of cellular microtubules against vinblastine-induced depolymerization, a microtubule-stabilizing, taxol-like effect. The microtubule-stabilizing effect of tubercidin is dose dependent and limited by the cytotoxicity of the agent. Tubercidin represents another natural product that interacts with microtubules and is one of the few to cause microtubule stabilization.

Gastrointestinal problems in patients who have type-III osteogenesis imperfecta

We performed a study of forty-three patients who had type-III osteogenesis imperfecta. Our purpose was to determine the frequency and severity of abdominal problems and the relationship between these problems and pelvic deformity. Twelve patients had had recurrent episodes of abdominal pain. Eleven of them had a history of chronic constipation, and five had been treated for fecal impaction. Radiographs had been made for ten of these patients, and eight of them had radiographic evidence of pelvic deformity with severe acetabular protrusion. Chronic constipation and recurrent abdominal pain are more frequent in patients who have osteogenesis imperfecta and acetabular protrusion than in those who do not have protrusion. These patients may benefit from early attention to a bowel program and referral to a gastrointestinal specialist.

An enzyme-linked immunosorbent assay for urinary screening of fentanyl citrate abuse

An enzyme-linked immunosorbent assay (ELISA) for quantitation of urinary fentanyl was evaluated as a screening tool for detecting abuse of this potent narcotic. The assay was found to have reproducible calibration curves from 0.5 to 10 ng/mL and a limit of detection of 0.5 ng/mL. Interference by proteins, glucose, or pH was negligible. The assay was specific for fentanyl with little cross-reactivity against despropionyl fentanyl and norfentanyl metabolites, other analgesics and common drugs of abuse. To evaluate its use in humans, urines were collected from 57 normal individuals, 48 patients seen in the Emergency Department, and 18 surgical patients receiving either low (50 micrograms) or moderate fentanyl dosage (200 and 250 micrograms) for routine anesthesia. In patients receiving 50 micrograms (a dose consistent with early abuse), urinary fentanyl was detectable for 3 to 10 h post administration. In patients receiving 200 or 250 micrograms (a dose more consistent with addiction), urinary fentanyl was detectable for longer time periods (> 24 h). These results indicate that the ELISA is sensitive for the detection of recent fentanyl exposure under conditions likely to mimic those in abuse and addiction. The assay is simple to perform, reliable, and can be used to screen urine specimens prior to gas chromatography/mass spectrometry (GC/MS) confirmation.

Welwitindolinone analogues that reverse P-glycoprotein-mediated multiple drug resistance

Welwitindolinones are a family of novel alkaloids recently isolated from the blue-green alga Hapalosiphon welwitschii as a part of our effort to identify new compounds that overcome multiple drug resistance. The abilities of three structurally similar members of this family to interact with P-glycoprotein have been compared. Similarly to the effects of verapamil, N-methylwelwitindolinone C isothiocyanate (compound 1) attenuated the resistance of MCF-7/ADR cells to natural product anticancer drugs, including vinblastine, taxol, actinomycin D, daunomycin, and colchicine, without affecting the cytotoxicity of cisplatin. These effects of compound 1 were apparent at doses as low as 0.1 microM, indicating that it is considerably more potent than verapamil for reversal of resistance. Welwitindolinone C isothiocyanate (compound 3) demonstrated weaker reversing activity, whereas an analogue of compound 1 in which the isothiocyanate group is replaced by an isonitrile group (compound 2) was inactive. The accumulation of [3H]vinblastine in SK-VLB-1 cells was increased by compound 1 > compound 3 > verapamil >> compound 2. Interestingly, only compound 1 and verapamil enhanced [3H]taxol accumulation by these cells. Photoaffinity labeling of P-glycoprotein with [3H]azidopine in membranes from SK-VLB-1 cells was inhibited by compounds 1 and 3, but not by compound 2. Therefore, the differences in the size and/or the electronegativity of the isothiocyanate and isonitrile moieties appear to dramatically affect the abilities of the compounds to interact with P-glycoprotein.

Lifetime and five-year prevalence of homelessness in the United States

OBJECTIVE

Intense debate exists concerning the number of homeless people in the United States. Previous studies, counting currently homeless people, have provided point-prevalence estimates of homelessness but have been criticized on methodological grounds. This study reports lifetime and 5-year prevalence estimates of homelessness using a different methodological approach.

METHODS

Random-digit dialing was used to interview 1507 adults living in households with telephones in the 48 contiguous states in the fall of 1990. Respondents were asked whether they had ever been homeless and if so, where they had slept while homeless.

RESULTS

Lifetime and 5-year prevalence of all types of homelessness combined were 14.0% (26 million people) and 4.6% (8.5 million people), respectively. Lifetime "literal homelessness" (sleeping in shelters, abandoned buildings, bus and train stations, etc.) was 7.4% (13.5 million people). Five-year (1985 through 1990) prevalence of self-reported homelessness among those who had ever been literally homeless was 3.1% (5.7 million people).

CONCLUSIONS

The magnitude of the problem of homelessness is much greater than most previous attempts to enumerate homeless people have led us to believe. This finding requires reconsideration of inferences about the causes of homelessness that were derived from point-prevalence studies of currently homeless people.

Cryptophycin: a new antimicrotubule agent active against drug-resistant cells

Cryptophycin is a cytotoxic dioxadiazacyclohexadecenetetrone isolated from cyanobacteria of the genus Nostoc. Incubation of L1210 leukemia cells with cryptophycin resulted in dose-dependent inhibition of cell proliferation in parallel with increases in the percentage of cells in mitosis (half-maximal effects at < 10 pM). Indirect immunofluorescence studies demonstrated that treatment of A-10 vascular smooth muscle cells with cryptophycin results in marked depletion of cellular microtubules and reorganization of vimentin intermediate filaments, similar to the effects of vinblastine. Cytochalasin B caused the depolymerization of microfilaments in these cells, while neither vinblastine nor cryptophycin affected this cytoskeletal component. Pretreatment of cells with taxol prevented microtubule depolymerization in response to either vinblastine or cryptophycin. While microtubule depolymerization in response to vinblastine was rapidly reversed by removal of the drug, cells treated with cryptophycin remained microtubule depleted for at least 24 h after removal of the compound. Combinational treatments with vinblastine and cryptophycin resulted in additive cytotoxicity. Ovarian carcinoma and breast carcinoma cells which are multiply drug resistant due to overexpression of P-glycoprotein are markedly less resistant to cryptophycin than they are to vinblastine, colchicine, and taxol. Therefore, cryptophycin is a new antimicrotubule compound which appears to be a poorer substrate for P-glycoprotein than are the Vinca alkaloids. This property may confer an advantage to cryptophycin in the chemotherapy of drug-resistant tumors.

In vivo expression of P-glycoprotein in a human colon carcinoma xenograft is modulated by therapy with free and monoclonal antibody-conjugated vinca alkaloids

Well established UCLA-P3 human lung tumor xenografts were significantly regressed by treatment with a monoclonal antibody-vinca immunoconjugate whereas no regressions were observed for the LS174T and SW948 human colon carcinoma xenografts by this therapy. Antibody and complementary DNA probes utilized for detection of the MDR1 gene product and mRNA levels, respectively, revealed that prior to drug treatment the lung tumor had virtually no detectable P-glycoprotein while both colon carcinomas displayed low and heterogeneous expression of this resistance-related protein. It was subsequently determined, however, that the low level of P-glyocoprotein expression observed for one of the colon tumors could be rapidly modulated following therapy with free or MoAb-conjugated vinca. These data indicated that elevated P-glycoprotein levels resulting from drug therapy may play a role in the lack of regression of the human colon xenografts. Most significantly, our results also indicated that the time interval between drug treatment and tissue sampling may be a critical factor to be considered in studies which attempt to correlate P-glycoprotein expression with chemotherapy.

beta-Carbolines from the blue-green alga Dichothrix baueriana

Three new chlorine-containing beta-carbolines, bauerines A-C (1-3), have been isolted from the terrestrial blue-green alga Dichothrix baueriana GO-25-2, and identifying mass and nmr spectral analysis. The alkaloids show activity against herpes simplex virus type 2.

Nemesis revisited: tuberculosis infection in a New York City men's shelter

In November 1990, a screening was conducted to determine the point prevalence of tuberculosis infection in a volunteer sample of homeless men (n = 161) living in a congregate shelter in New York City. Of those for whom we have results (n = 134), 79% were positive for tuberculosis. The mean length of shelter stay from date of shelter entry was 31.8 months and was significantly associated with the tuberculosis infection rate. The findings suggest that crowded living conditions and the presence of a stable resident pool in crowded congregate shelters may be associated with transmission of tuberculosis infection.

Characterization of beta-adrenergic receptors on rat and human osteoblast-like cells and demonstration that beta-receptor agonists can stimulate bone resorption in organ culture

We have shown by receptor-binding analyses that the beta-2 adrenergic receptor is present on rat ROS 17/2.8 osteoblast-like cells. This was confirmed by PCR amplification of cDNA copied from the mRNA. The beta-1 adrenoreceptor subtype was absent and its mRNA was not detectable, even at the level of sensitivity afforded by PCR analysis. The beta-adrenergic receptors present on ROS 17/2.8 cells were functional as measured by ligand-induced enhancement of cAMP production. We investigated whether adrenergic agonists could mimic the action of PTH to stimulate bone resorption in neonatal mouse calvariae in organ culture. PTH induced a large increase in cAMP while norepinephrine and isoproterenol induced a small but significant increase. In the presence of a phosphodiesterase inhibitor and an antioxidant, norepinephrine consistently stimulated bone resorption. In order to determine whether functional beta-adrenergic receptors were unique to ROS 17/2.8 cells, human SaOS-2 osteoblast-like cells were also examined for enhancement of cAMP production by norepinephrine, and essentially the same results were obtained. Thus, adrenergic agonists efficiently activate beta-receptors on two osteoblast-like cells and can stimulate bone resorption in intact mouse calvariae.

Inhibition of reverse transcriptase activity by extracts of cultured blue-green algae (cyanophyta)

Lipophilic and hydrophilic extracts of over 900 strains of cultured blue-green algae (cyanophyta) were examined in vitro for their ability to inhibit the reverse transcriptases (RT) of avian myeloblastosis virus (AMV) and human immunodeficiency virus, type 1 (HIV-1). Eighteen (2.0%) aqueous extracts showed activity against AMV and HIV RTs. The maximal level of RT inhibition achieved by some of the active extracts was equivalent to that measured for 3'-azido-2',3'-di-deoxythymidine (AZT) at 668 ng/ml. Examination of partially purified fractions prepared by C18 column chromatography demonstrated that the RT inhibition observed could not be attributed entirely to the degradation of transcript DNA, template RNA, or enzyme protein in the reaction mixture. Thus, these results indicate that cultured blue-green algae may represent a novel source of compounds that inhibit RT activity, including that of HIV-1.