Helicase inhibition by anthracycline anticancer agents

Helicases are essential to both DNA replication and transcription because they separate double-stranded DNA, preparing the single strands for replication or transcription. Because the anti-cancer anthracycline antibiotics stabilize double-stranded DNA primarily by their intercalative binding, we expected the intercalated antibiotics to interfere with helicase action. We examined anthracycline antibiotic effects on SV40 large T antigen helicase activity, using a duplex DNA helicase substrate of 32P-labeled 17-mer annealed to complementary M13mp19(+) circular single-stranded DNA. The T antigen helicase activity was potently inhibited by the anthracycline antibiotics. The T antigen helicase IC50 values for the anthracycline antibiotics were as follows: nogalamycin, 2 x 10(-7) M; daunorubicin, 4 x 10(-7) M; doxorubicin, 4 x 10(-7) M; idarubicin, 1.8 x 10(-6) M; 4'-epidoxorubicin, 2 x 10(-6) M; aclacinomycin, 4 x 10(-6) M; and menogaril, 6 x 10(-6) M. Partially purified helicases from HeLa cells and murine mammary carcinoma FM3A cells also were potently inhibited by doxorubicin, with IC50 values of 4 x 10(-7) M and 9 x 10(-7) M, respectively. Because the abundance, specificities, and types of helicases vary in the cell, this site of action for anthracycline antibiotics may help explain anthracycline potency, drug specificity for DNA or RNA inhibition, and some types of cellular resistance to these drugs.

Biocompatibility of retrograde filling materials in the ferret canine. Amalgam and IRM

Periapical tissue response to retrograde fillings of amalgam and IRM were compared in the mandibular canine of the adult male ferret. Teeth were cleaned and shaped with a standard technique and obturated with gutta-percha. The root apex was then exposed and retrofillings were placed. The animals were grouped according to observation periods of 5, 10, and 15 weeks. At the proper time the animals were killed and the lower canine tooth along with the surrounding bone was removed. The tissue blocks were examined clinically, radiographed, and prepared for histologic examination. The clinical and radiographic examination indicated both materials to be well tolerated by periapical tissues. Microscopic examination of amalgam specimens showed a decrease in inflammation and the formation of a fibrous capsule over the 15-week period. IRM specimens showed persistent inflammation and slower healing potential.

Effect of musculoskeletal development on the prediction of body density in females

The purpose of this study was to determine if musculoskeletal development had a significant effect on the prediction of body density in females. Subjects consisted of 156 females aged 17 to 44 years. Subjects were divided into three groups on the basis of musculoskeletal development as determined by the Heath-Carter Anthropometric Somatotype mesomorphy rating. Anthropometric measurements included eight skinfold measures (tricep, subscapula, chest, midaxillary, abdomen, suprailiac, thigh, and calf), body diameters of the humerus and femur, and circumferences at five locations (waist, forearm, upper arm, calf, and gluteal). Residual lung volume was determined by the closed circuit oxygen dilution method prior to the measurement of body density by hydrostatic weighing. A regression equation was developed to predict body density from the sum of seven skinfolds, sum of seven skinfolds squared, age, and mesomorphy rating. A similar regression equation was developed using the sum of three skinfolds, sum of three skinfolds squared, and the other variables. Results indicated that mesomorphy rating did not contribute significantly to the prediction of body density in females. It was concluded that musculoskeletal development did not have a significant effect on the prediction of body density in females.

Who Plays? Who Sits?

In brief Allowing a player to return to competition too soon after a concussion may result in further injury or even death. By carefully evaluating and monitoring an athlete who sustains a concussion, then classifying the concussion by severity, the physician can determine whether the athlete can safely return to play.

Comparing Health Status: Native peoples of Canada, Aborigines of Australia, and Maoris of New Zealand

European settlers in Canada, Australia, and New Zealand each developed similar policies in dealing with the indigenous peoples of the land they colonized. As a result of contact with the Europeans, these peoples experinced dispossession, deprivation, and demographic decline. Their morbidity and mortality retes are consistently higher than those of the nonindigenous population. To achieve further improvement in their health status, indigenous peoples must begin to play a dominant role in the planning and delivery of health care services.

Health and psychosocial issues of individuals with incomplete and resolving spinal cord injuries

Longitudinal data and clinical experience indicate that a greater proportion of spinal cord injuries result in incomplete or resolving neurological lesions. Although it has been reported that persons with incomplete injuries enjoy better functional outcomes, routine contacts with these individuals indicate that many experience problems and complications strikingly similar to those with complete spinal cord injuries. Thus, to document the issues and needs of these individuals, data from Colorado's population-based spinal cord injury surveillance program were analyzed. Of 330 persons registered since January 1, 1986, 121 (37%) were found to be minimally disabled (Frankel class D or E). Review of medical records and follow up documentation for these individuals indicated that although over 75% were ambulatory and virtually all were physically independent, more than 80% did report problems in one or more areas: 21% had orthopedic issues and 17% faced additional spinal surgery; 16% reported neurological deterioration or increased spasticity; 25% had pain problems; and 16% had bladder difficulties. Other issues included bowel problems, blood pressure abnormalities, skin breakdown, sexual difficulties, depression, and unemployability. Implications for rehabilitation are discussed in the light of these and other findings.

The cyclic nucleotide specificity of three cAMP receptors in Dictyostelium

cAMP receptors mediate signal transduction pathways during development in Dictyostelium. A cAMP receptor (cAR1) has been cloned and sequenced (Klein, P., Sun, T. J., Saxe, C. L., Kimmel, A. R., Johnson, R. L., and Devreotes, P. N. (1988) Science 241, 1467-1472) and recently several other cAR genes have been identified (Saxe, C. L., Johnson, R., Devreotes, P. N., and Kimmel, A. R. (1991a) Dev. Genet. 12, 6-13; Saxe, C. L., Johnson, R. L., Devreotes, P. N., and Kimmel, A. R. (1991b) Genes Dev. 5, 1-8). We have expressed three receptor subtypes, cAR1, cAR2, and cAR3, in growing cells and have investigated their affinity and pharmacological specificity in a series of [3H]cAMP binding studies. In phosphate buffer, there were two affinity states of about 30 and 300 nM for cAR1 and 20 and 500 nM for cAR3 but no detectable affinity for cAR2. In the presence of 3 M ammonium sulfate, there was one affinity state of 4 nM for cAR1 and 11 nM for cAR2 and two affinity states of approximately 4 and 200 nM for cAR3. The relative affinities of 14 cyclic nucleotide derivatives were tested for each cAR in ammonium sulfate. These studies suggest a model (Van Haastert, P. J. M., and Kien, E. (1983) J. Biol. Chem. 258, 9636-9642) in which cAMP binds to all three receptor subtypes by maintaining hydrogen bond interactions at the N6 and O3' positions. Interactions at the exocyclic oxygens of cAMP varied between the receptors; cAR2 and cAR3 lacked a stereoselective interaction at the axial oxygen which was present in cAR1. The cleft, which binds the adenine ring of cAMP, was hydrophobic in cAR1 and cAR3 but relatively polar in cAR2. The analog specificity of cAR1 and cAR3 in phosphate buffer was similar to that measured in ammonium sulfate though the derivatives' relative affinity to cAMP was reduced. We conclude that these cAMP receptor subtypes can be distinguished by distinct pharmacological properties which will allow selective activation of each cAR during development.

Vasculitic and encephalitic complications associated with Coccidioides immitis infection of the central nervous system in humans: report of 10 cases and review

Six cases of apparent and four cases of histopathologically confirmed vasculitis of the central nervous system (CNS), including one case of histopathologically documented vasculitis with encephalitis associated with coccidioidal meningitis (CM), are presented. Vasculitic complications included changes in mental status as well as stroke-like findings of aphasia, hemianopsia, and hemiparesis. Seven patients died. Vasculitic complications were unanticipated and often abrupt in onset, and delayed therapeutic intervention was characteristic. The diagnosis of vasculitis/encephalitis due to Coccidioides immitis infection must be based on clinical judgment, since serum antibody titers, cerebrospinal fluid findings, and initial radiological studies are not always helpful. Institution of both intravenous and intracisternal administration of amphotericin B and possibly concomitant intravenous administration of dexamethasone may be warranted in situations in which the association of C. immitis with CNS vasculitis or encephalitis appears likely before serologic or cultural confirmation of C. immitis infection involving the CNS is available.

Glomerular epithelial cells secrete a glomerular basement membrane-degrading metalloproteinase

Cultured rat glomerular epithelial cells (GEC) were examined for their ability to release extracellular matrix-degrading proteinases with [3H]gelatin as substrate. GEC-conditioned media, under serum-free conditions, contained modest amounts of gelatinase activity (1 to 10 U/mg of protein); the activity was maximal at neutral pH, was inhibited by zinc chelators, was not inhibited by tissue inhibitor of metalloproteinase-2, and could not be further activated by trypsin or organomercurials. Gelatin substrate sodium dodecyl sulfate-polyacrylamide gels of GEC-conditioned medium revealed several zones of lysis, with molecular sizes of 150 kd (major band), and 220, 86 to 93, and 52 to 54 kd (minor bands). Northern blot analysis demonstrated that the GEC metalloproteinase(s) were distinct from the 68- to 72-kd type IV collagenase/gelatinase present in mesangial cells or the 92-kd type IV collagenase present in neutrophils. The GEC gelatinolytic activity also degraded insoluble type IV collagen in glomerular basement membrane in a dose-dependent manner. The major metalloproteinase activity responsible for the type IV collagen degradation has a molecular size of 150 kd with a type IV collagen substrate gel. Thus, GEC produce several neutral metalloproteinases, which, by virtue of their substrate specificity, may play an important role in glomerular basement membrane remodeling and in glomerular diseases characterized by alterations in basement membrane permeability.

How to Manage Skier's Thumb

In brief Injury to the ulnar collateral ligament of the thumb is relatively common among skiers. Because the injury has a propensity for causing long-term complications, patients require meticulous follow-up and-if the ligament is unstable, or if the stability of the injured ligament is unknown-early referral. X-rays are imperative for ruling out fractures, and they sometimes show the extent of injury. Stress examination will also help delineate management. Primary care physicians can treat most incomplete sprains successfully with a thumb cast followed by hand or occupational therapy; patients with complete ruptures should be referred to an orthopedist.

Guidelines for reducing the risk of disease transmission in the psychophysiology laboratory. SPR Ad Hoc Committee on the Prevention of Disease Transmission

The acquired immunodeficiency syndrome (AIDS) pandemic has highlighted the need for safeguards against the inadvertent transmission of infectious disease in the psychophysiology laboratory. These Guidelines identify factors contributing to the risk of bloodborne disease transmission to subjects or technicians, and recommend procedures to minimize such risk, given current knowledge and techniques. The lowest risk is associated with the application of devices, such as surface electrodes, to nonabraded, intact skin. Such devices should be clean, but do not require disinfection. The potential risk of infection is higher when surface electrodes are applied to non-intact skin. Abrasion, or other breaks in the skin, can allow seepage of blood products carrying such pathogens as hepatitis B virus and the human immunodeficiency virus that causes AIDS. Thus electrodes require high-level disinfection before reuse on non-intact skin. In addition, technicians should wear gloves during skin preparation and should abrade the skin no more than necessary, using only sterile, preferably non-sharp materials. The highest risk is that associated with items that enter sterile tissue, such as subdermal electrodes and the needles and lancets sometimes used in skin preparation. Such items must be sterile at the time of use and must be handled with extreme caution.

Function of the quadriceps and hamstrings muscles in knees with chronic partial deficiency of the anterior cruciate ligament. Isometric and isokinetic evaluation

We assessed the isokinetic and isometric strength and power profile of the knees of 37 patients who had a previous grade II sprain (partial tear) of the anterior cruciate ligament. Of the 37 knees, 11 had an isolated partial anterior cruciate ligament rupture and 26 had a partial anterior cruciate ligament rupture combined with a partial medial collateral ligament rupture. The Cybex II isokinetic dynamometer was used in the measurements. Eight years after the injury, the mean strength deficit of the injured knees was minimal when compared with the uninjured side. In the hamstrings of both groups, the relative strength deficit increased significantly with a higher speed of isokinetic movement (P less than 0.05). Compared with the strength parameters (peak torques), the other functional parameters (total work, average power, and peak angular impulse) of the injured knees showed some, but not significantly greater, deficits (hamstrings, 7% to 10%; quadriceps, 4% to 10%). We found that the general thigh muscle function in knees with old grade II sprains of the anterior cruciate ligament appears adequate except in flexion where the strength deficits are significantly greater in higher speeds of isokinetic movement. Therefore, rehabilitation using high-speed flexion (and extension) exercises is recommended.

Orofacial pain: diagnosis and treatment

Orofacial pain can have an inflammatory, neurologic or musculoskeletal cause. Inflammatory diseases include dental abscess, sinusitis, temporal arteritis, sialolithiasis and infections of the parotid gland. Common neurologic diseases that cause facial pain are trigeminal neuralgia, glossopharyngeal neuralgia, paratrigeminal neuralgia and cluster headaches. Musculoskeletal causes include temporomandibular joint syndrome and myofascial pain dysfunction syndrome. A clear understanding of pertinent anatomy and an organized approach to diagnosis will facilitate the evaluation of patients with orofacial pain.

The internal cardioverter defibrillator: patient-family teaching

The ICD has proved to be a valuable therapeutic adjunct for patients at risk for sudden cardiac death. Careful attention to details associated with patient and family teaching assures a smooth adaptation to what may seem an overwhelming circumstance for patients and family members.

Activity of the conformationally rigid 2-amino-4-phosphonobutanoic acid (AP4) analogue (RS)-1-amino-3-(phosphonomethylene)cyclobutane-1-carboxylic acid (cyclobutylene AP5) on evoked responses in the perforant pathway of rat hippocampus

The highly rigid and conformationally extended 2-amino-4-phosphonobutanoic acid (AP4) analogue (RS)-1-amino-3-(phosphonomethylene)-cyclobutane-1-carboxylic acid (cyclobutylene AP5) was synthesized and found to inhibit evoked responses in the rat lateral perforant path (LPP) with an IC50 of 41 (+/- 1.5 S.E.M.) microM and the medial perforant pathway with an IC50 of 218 (+/- 3.7 S.E.M.) microM. Furthermore, paired pulse potentiation experiments suggest that cyclobutylene AP5 acts, in part, at a presynaptic site in the LPP. Thus, cyclobutylene AP5 appears to act in a similar manner to L-AP4 in the perforant pathway. These data support the hypothesis that L-AP4 assumes an extended conformation at the L-AP4 receptor of the LPP.

The entrepreneurial physician

This article draws on the experience of interviews of hundreds of physicians in the last few years. Those at mid-career have deep concerns about what lies ahead for them. A character, Dr. Charles Evans, has been created to describe some of the major possibilities being thought about and explored by physicians who believe their profession is now changing in ways they never had anticipated.

The role of NAD(P)H:quinone oxidoreductase in mitomycin C- and porfiromycin-resistant HCT 116 human colon-cancer cells

A mitomycin C (MMC)- and porfiromycin (PFM)-resistant subline of the HCT 116 human colon-cancer cell line was isolated after repeated exposure of HCT 116 cells to increasing concentrations of MMC under aerobic conditions. The MMC-resistant subline (designated HCT 116-R30A) was 5 times more resistant than the parent cells to MMC and PFM under aerobic conditions. Both the MMC-resistant cells and the parent HCT 116 cells accumulated similar amounts of PFM by passive diffusion, but levels of macromolecule-bound PFM were about 50% lower in the resistant cell line, implying a decrease in PFM reductive activation in the resistant cells. The finding that microsomes from either sensitive or resistant cells showed an equal ability to reduce MMC and PFM indicated that the activity of NADPH cytochrome P-450 reductase (EC 1.6.2.4) was not changed in the resistant subline. Soluble extracts of HCT 116 cells reduced MMC and PFM more effectively at pH 6.1, and NADH and NADPH were utilized equally well as electron donors under both aerobic and anaerobic conditions. These data suggest that quinone reductase (EC 1.6.99.2; DT-diaphorase) in soluble extracts is responsible for the reduction of MMC. Quinone reductase activities in soluble extracts of HCT 116-R30A cells for the reduction of dichlorophenol indophenol (DCPIP) and menadione-cytochrome c at optimal pHs were decreased by 95% as compared with those obtained in parent cells. However, the MMC-reducing activity of HCT 116-R30A soluble extracts was only 50% lower than that of the parent cell extracts. The kinetic constants (Km, Vmax) found for quinone reductase in the two cell lines with respect to the substrates DCPIP and menadione differed. Two species of mRNA for quinone reductase (2.7 and 1.2 kb) were detected in both cell lines, and there was no detectable difference between parent and resistant cells in the steady-state level of either of these mRNA species. Furthermore, incubation with the quinone reductase inhibitor dicoumarol rendered HCT 116 cells more resistant to MMC. Alteration of the quinone reductase activity in HCT 116-R30A cells appears to be the mechanism responsible for their resistance to MMC and PFM.

The natural history of medical and psychiatric disorders in an American Indian community

In 1969, a Pacific Northwest American Indian community cohort (n = 100) was interviewed for the presence of physical and psychiatric illnesses. The same community was studied again in 1988. This study describes the outcome among the original 100 subjects. The schedule for Affective Disorders and Schizophrenia Lifetime Version (SADS-L) served as the basic interview instrument, supplemented by data from medical records, death certificates, and medical and community informants. Twenty-five subjects had died, 13 from cardiovascular disorders and seven from alcohol-related illnesses. Among the 46 subjects re-interviewed, hypertension, heart disease, and diabetes had become significant sources of medical morbidity. Alcoholism was the most significant cause of psychiatric morbidity, particularly among males. This study indicates that greater attention should be focused upon prevention and treatment of alcoholism, cardiovascular disorders, and diabetes in this community and in other American Indian populations.

Psychiatric epidemiology of an Indian village. A 19-year replication study

This 1988 study reports the point and lifetime prevalence of psychiatric disorders, using DSM-III-R criteria, of a sample (approximately 25%) of adult members of an Indian village previously studied in 1969. The basic instrument was the Schedule for Affective Disorders and Schizophrenia, augmented by available medical information and administered by experienced psychiatrists. Subjects were interviewed and results were weighed for the age- and sex-distributed population. The results indicated a high point prevalence of alcohol dependence (32.8%), with a lifetime prevalence of 72.8%, among males. The lifetime prevalence of affective disorders among women was also high (36.8%), but less so among men (19.3%). When compared with the DSM-III-R diagnoses of the 1969 study, the point prevalence rates of alcohol dependence and abuse disorders fell from 39% to 21%. Also, fewer subjects were judged to be psychiatrically impaired. Even though the prevalence of psychiatric disorders was lower in the current study, the rates for alcohol disorders and affective disorders were still far higher than those reported in Epidemiologic Catchment Area studies. Alcohol dependence (especially among young men) and affective disorder (among women) were major problems.

Characterization of retinal and hippocampal L-AP4 receptors using conformationally constrained AP4 analogues

In the past, the absence of useful 2-amino-4-phosphonobutanoic acid (AP4) analogues has hampered the pharmacological study and comparison of different systems which are sensitive to L-AP4. Several conformationally constrained AP4 analogues have now been synthesized: (E)- and (Z)-1-amino-3-phosphonocyclopentanecarboxylic acid [(E)- and (Z)-cyclopentyl AP4], and (E)- and (Z)-1-amino-3-phosphonocyclohexanecarboxylic acid [(E)- and (Z)-cyclohexyl AP4], and the recently synthesized cyclopropyl analogues (E)- and (Z)-2-amino-2,3-methano-4-phosphonobutanoic acid [(E)- and (Z)-cyclopropyl AP4]. Therefore, we have examined and report here the pharmacology of two retinal and two hippocampal L-AP4 sensitive systems using these analogues. In addition, the pharmacology of two kainic acid/alpha-amino-3-hydroxy-5-methylisoxazole-4- propionic acid (KAIN/AMPA) pathways and one N-methyl-D-aspartate (NMDA) hippocampal pathway was examined. We found that the rank order potency of the L-AP4 sensitive systems were similar though not identical. The KAIN/AMPA and NMDA systems had a quite different rank order of potencies than the L-AP4 systems. These data suggest that the L-AP4 receptors in these different systems are structurally similar to each other and differ from both KAIN/AMPA and NMDA receptors.