Structure of tropomyosin at 9 angstroms resolution

We have used molecular replacement followed by a highly parameterized refinement to determine the structure of tropomyosin crystals to a resolution to 9 A. The shape, coiled-coil structure and interactions of the molecules in the crystals have been determined. These crystals have C2 symmetry with a = 259.7 A, b = 55.3 A, c = 135.6 A and beta = 97.2 degrees. Because of the unusual distribution of intensity in X-ray diffraction patterns from these crystals, it was possible to solve the rotation problem by inspection of qualitative aspects of the diffraction data and to define unequivocally the general alignment of the molecules along the (332) and (3-32) directions of the unit cell. The translation function was then solved by a direct search procedure, while electron microscopy of a related crystal form indicated the probable location of molecular ends in the asymmetric unit, as well as the anti-parallel arrangement. The structural model we have obtained is much clearer than that obtained previously with crystals of extraordinarily high solvent content and shows the two alpha-helices of the coiled coil over most of the length of the molecules and establishes the coiled-coil pitch at 140(+/- 10) A. Moreover, the precise value of the coiled-coil pitch varies along the molecule, probably in response to local variations in the amino acid sequence, which we have determined by sequencing the appropriate cDNA. The crystals are constructed from layers of tropomyosin filaments. There are two molecules in the crystallographic asymmetric unit and the molecules within a layer are bent into an approximately sinusoidal profile. Molecules in consecutive layers in the crystal lie at an angle relative to one another as found in crystalline arrays of actin and myosin rod. There are three classes of interactions between tropomyosin molecules in the spermine-induced crystals and these give some insights into the molecular interactions between coiled-coil molecules that may have implications for assemblies such as muscle thick filaments and intermediate filaments. In interactions within a layer, the geometry of coiled-coil contacts is retained, whereas in contacts between molecules in adjacent layers the coiled-coil geometry varies and these interactions instead appear to be dominated by the repeating pattern of charged zones along the molecule.

A calcineurin-like phosphatase is required for catch contraction

The ability of certain molluscan smooth muscles to maintain a prolonged state of contraction, termed 'catch', has been correlated with the activity of a calcineurin-like Ca(2+)-regulated phosphatase. The release of this phosphatase through extensive treatment of fibers with detergent, as shown by Western blots and a calmodulin-binding overlay assay, results in the loss of catch tension maintenance. This effect is reversed by perfusion of the fiber with brain calcineurin. These findings suggest that the activity of the calcineurin-like phosphatase, switched on during the onset of active contraction, plays a critical role in the maintenance of catch.

Comparison of cell proliferation in breast carcinoma using image analysis (Ki-67) and flow cytometric systems

Cellular proliferation has been implicated as an important predictor of biologic behavior in breast cancer. Cellular proliferation of 95 breast carcinomas was evaluated by comparing Ki-67 immunoreactivity in frozen sections quantitated by image analysis with S-phase and S + G2/M phase fraction determined by flow cytometry on nuclei extracted from fixed, paraffin-embedded sections (modified Hedley's technique). These parameters were correlated with traditional morphologic features of histologic grade, including mitotic count. Ki-67 immunoreactivity correlated with S-phase fraction determined by flow cytometry (r = .41, P = .001) and with S + G2/M phase fraction determined by flow cytometry (r = .29, P = .008). There was also a correlation between histologic grade and Ki-67 immunoreactivity (r = .30, P = .004) and between histologic grade and S-phase fraction (r = .42, P = .0001). Mitotic count correlated with Ki-67 immunoreactivity (r = .25, P = .015) and with S-phase fraction (r = .35, P = .001). Image and flow cytometric analysis systems provide comparable measurements of cellular proliferation; their measurements correlate with histologic grade and mitotic count in breast cancer.

The Test for Severe Impairment: an instrument for the assessment of patients with severe cognitive dysfunction

OBJECTIVE

To develop a reliable and valid test of cognitive function suitable for patients with severe cognitive impairment.

DESIGN

Administration of a test; test-retest reliability; comparison to traditional test.

SETTING

Chronic long-term-care facility.

PATIENTS OR OTHER PARTICIPANTS

The participants were 40 elderly residents with severe cognitive impairment.

MAIN OUTCOME MEASURES

Results of the Test for Severe Impairment (TSI) and its subsections (language, memory, executive function, and motor performance); correlation of test and retest scores; correlation of TSI with Mini-Mental State Exam.

RESULTS

The TSI was significantly correlated with the Mini-Mental State Exam (r = 0.83, P less than or equal to 0.0001). Test-retest reliability was high (r = 0.96, P less than 0.0001). The internal reliability of the test was also good (alpha = 0.90). Preliminary result of a factor-analysis suggests that factor scores may be derived that relate to memory, language production, and knowledge of body parts.

CONCLUSIONS

The TSI is a valid and reliable test of cognitive function in patients with severe cognitive impairment. It is appropriate to use it as a unified scale.

Multisite association by recombinant proteins can enhance binding selectivity. Preferential removal of immune complexes from serum by immobilized truncated FB analogues of the B domain from staphylococcal protein A

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DNA ploidy and cell cycle analysis in ear malignant melanoma by flow and image cytometry

Sixteen ear malignant melanomas (MM) were studied for ploidy and cell cycle analysis by flow and image cytometry. The results were compared with clinical (age, sex, stage), histologic (depth of invasion, level, type) and prognostic (recurrence, death) parameters. Single nuclear suspensions were obtained from fixed, paraffin-embedded tumor and adjacent normal tissue processed separately according to Hedley's technique. These, a "spiked" specimen of normal tissue and tumor, and a spleen diploid control were analyzed on a FACScan flow cytometer (Becton Dickinson, Mountain View, California, U.S.A.). Feulgen-stained Cytocentrifuge preparations of nuclear suspensions of normal, MM and diploid spleen were analyzed with the CAS 200 Image Analyzer (Cell Analysis Systems, Inc., Elmhurst, Illinois, U.S.A.) against commercial calibration rat hepatocytes defined as diploid. Six (37.5%) MM were diploid, and 10 (62.5%) were aneuploid; 8 (90%) were hypodiploid, for a high frequency. There were no statistically significant correlations between clinical, pathologic, prognostic or cell cycle analysis parameters and ploidy, although poor prognostic features tended to be in aneuploid lesions.

Analysis of the three-alpha-helix motif in the spectrin superfamily of proteins

Members of the spectrin superfamily of proteins contain different numbers of homologous repeats arranged in tandem. Each of these consists of a three-alpha-helix motif, comprising two similarly and one oppositely directed alpha-helical segment joined by nonhelical linkers of characteristic length. The right-handed alpha-helices each display a heptad repeat in their amino acid sequences indicative of left-handed coiled-coil-like packing. We have calculated the potential number of inter-helix ionic interactions that specify the spatial arrangement of the helices in the motif in terms of both the handedness of helix connectivity (left or right) and the relative axial stagger between the three alpha-helices. All of the models examined were constrained to have optimal coiled-coil packing. For alpha-spectrin and alpha-actinin the results provide strong support for a left-handed connectivity of the three helices and axial repeat lengths of 5.05 and 6.24 nm, respectively. Furthermore, the axial staggers between homologous segments in the preferred models are identical. The insights provided into the topography of this widespread tertiary fold may prove of value to those concerned with the problem of de novo protein design.

Expanding access to investigational new therapies

One important role for the primary care provider is to be familiar with all available treatment options for HIV disease. Because only a few treatments are approved, unapproved therapy becomes important for many patients. As a result, clinicians have had systems developed that create access to promising investigational drugs. In addition, because of the urgent need to increase the number of proven treatments, some clinicians have chosen to become more directly involved in the evaluation of new treatments for HIV disease by becoming community based "clinician-researchers."

Paramyosin inhibits complement C1

We report here the results of studies showing that inhibition of C is a property of several invertebrate paramyosins. Paramyosins from Taenia solium, Schistosoma mansoni, and the mussel Mytilus edulis bind polymeric collagen and can be isolated from crude extracts of tissues by collagen affinity. These paramyosins inhibit C1 function whether the C1 is isolated or present in C2-deficient serum. Because T. solium paramyosin was the best inhibitor, we concentrated further studies on this molecule. T. solium paramyosin binds purified C1q in solution with a dose/response similar to C1r2S2. Further studies of the C1-paramyosin interaction indicate that: 1) C4 is not activated, 2) C4b2a decay is not affected, and 3) there is no effect on the efficiency of C3-9, as provided in EDTA-chelated guinea pig serum, in lysing SRBC. Thus, paramyosin inhibition is directed at the initiation of the classical pathway. The results suggest that paramyosins of helminthic parasites may have a role as modulators of the host immune response through C inhibition at C1.

Paramyosin inhibits complement C1

We report here the results of studies showing that inhibition of C is a property of several invertebrate paramyosins. Paramyosins from Taenia solium, Schistosoma mansoni, and the mussel Mytilus edulis bind polymeric collagen and can be isolated from crude extracts of tissues by collagen affinity. These paramyosins inhibit C1 function whether the C1 is isolated or present in C2-deficient serum. Because T. solium paramyosin was the best inhibitor, we concentrated further studies on this molecule. T. solium paramyosin binds purified C1q in solution with a dose/response similar to C1r2S2. Further studies of the C1-paramyosin interaction indicate that: 1) C4 is not activated, 2) C4b2a decay is not affected, and 3) there is no effect on the efficiency of C3-9, as provided in EDTA-chelated guinea pig serum, in lysing SRBC. Thus, paramyosin inhibition is directed at the initiation of the classical pathway. The results suggest that paramyosins of helminthic parasites may have a role as modulators of the host immune response through C inhibition at C1.

Immunohistochemical progesterone receptor assay. Measurement by image analysis

To determine the efficiency of image analysis in immunohistochemical progesterone receptor (PgR) measurement, 94 primary breast carcinoma tissue samples were evaluated for PgR by biochemical dextran-coated charcoal assay (DCC) and an immunohistochemical method. Frozen sections immunostained for PgR with a monoclonal antibody (Abbott PgR-ICA, Chicago, IL) and the peroxidase-antiperoxidase technique were scored semiquantitatively histologic score by microscopy and quantitatively (percentage nuclear area immunopositivity [PNA] using the CAS 200 image analyzer (Cell Analysis Systems, Elmhurst, IL). There was a positive correlation between dextran-coated charcoal assay and both histologic score (r = 0.82) and PNA (r = 0.69). Selected cutoff points of 60 histologic score and 6.5% PNA based on sensitivity/specificity calculations yielded a predictive value of a negative test of 73% and 80%, respectively, and a positive predictive value of 100% for both; ranges of fmol/mg protein PgR correspond to ranges of histologic score and PNA. The use of an image analyzer to measure PNA in PgR-immunostained sections is a viable alternative to dextran-coated charcoal assay, especially when insufficient fresh tissue is available.

Drug self-administration methods in abuse liability evaluation

The human drug self-administration paradigm is an extension of the animal model developed in the 1960s. The paradigm can be used to investigate the determinants and correlates of drug-seeking and drug-taking behavior and has proven useful in the development of medications for treating drug dependence. This paper describes the basic components of the human self-administration model and discusses studies that illustrate some of its applications, including assessment of the reinforcing effects of drugs, analysis of behavioral and pharmacological mechanisms of drug self-administration and measurement of the abuse liability, behavioral toxicity, and aversive effects of drugs. Some of the strengths and limitations of using the paradigm with human research subjects are also presented. It is concluded that the drug self-administration model should not replace other measures of abuse liability testing in humans, but should be incorporated into comprehensive programs of drug abuse assessment wherever possible.

Cigarette smoking and addiction

Tobacco use is a form of drug addiction, as shown by studies assessing the abuse liability of tobacco and nicotine in humans and animals. Tobacco experimentation frequently leads to daily use, which is characterized by a highly consistent pattern of drug intake. Such a pattern is controlled by the biologic concentrations of nicotine, a psychoactive constituent of tobacco smoke. Nicotine is a euphoriant, self-administered by humans as well as by animals in laboratory settings. Nicotine controls smokers' behavior in such a way that reducing or suppressing tobacco consumption produces a withdrawal syndrome characterized by irritability, difficulty concentrating, cognitive impairments, and weight gain. Nonpharmacologic factors are also important determinants of tobacco addiction that interfere with successful cessation. Strategies to treat tobacco addiction are comparable to those developed for other drug addictions. For example, therapy may include the use of alternate forms of nicotine and possibly also nicotine antagonists and medications targeted to alleviate specific withdrawal symptoms, if such therapies become available. As in all drug addiction treatment strategies, behavioral intervention is important whether or not a medication is used.

Fibrinogen structure in projection at 18 A resolution. Electron density by co-ordinated cryo-electron microscopy and X-ray crystallography

Electron microscope images of frozen-hydrated crystals of a proteolytically modified fibrinogen show excellent preservation of the structure. An electron density map of the key centric projection of the crystal at 18 A resolution has been obtained by combining the phases derived from cryo-electron microscopy with X-ray amplitudes. Simulation methods developed in earlier studies have been used to interpret the map. In contrast to the earlier images, the map allows us to visualize the coiled-coil region of the molecule and possible substructure in the beta domains. The map also shows that there is a marked difference in density in the two regions corresponding to the molecular ends where the gamma domains interact. A possible interpretation of this finding is provided by assuming substructure in the gamma domains and the breaking of molecular symmetry where these domains interact. Some additional constraints useful for the determination of the three-dimensional structure were obtained from cryo-electron micrographs of a perpendicular view at 25 A resolution. Implications of this working model for the molecular length and contacts in the filaments in both the crystal and fibrin are described. The data used here will be valuable as a starting point for obtaining the three-dimensional structure.

Serotonin immunoreactivity in pancreatic endocrine neoplasms (carcinoid tumors)

Primary serotonin secreting pancreatic endocrine neoplasms (carcinoid tumors) are extremely rare and may be associated with manifestations of the carcinoid syndrome. Two cases of primary carcinoid tumor of the pancreas with liver metastases showed clinical and biochemical features of the carcinoid syndrome. Both cases demonstrated strong positive immunoreactivity for serotonin within the tumor cells. In an attempt to determine the relationship between pancreatic carcinoid tumors and other pancreatic endocrine neoplasms, immunostains for serotonin were performed on 11 additional islet cell tumors and on non-neoplastic pancreatic tissues. These cases showed serotonin immunoreactivity within islet cell tumors (36%). In addition, focal staining for serotonin was present in non-neoplastic ducts and ductules (88%), acini (22%), and islets of Langerhans (33%). Based on these observations, specific criteria are suggested for the diagnosis of primary pancreatic carcinoid tumor.

DNA ploidy studies of benign and malignant tumours: comparison of flow cytometry and image analysis techniques using two types of cytological specimen

DNA ploidy studies were carried out on Feulgen stained smears and cytocentrifuge preparations from 35 malignant tumours and four benign neoplasms using the CAS image analyser. The smears were prepared from scrapings from fresh tumour tissue whereas the cytocentrifuge preparations were prepared from single nuclear suspensions from paraffin-embedded cell blocks from the same tumour. Histograms obtained by image analysis of the tumour scrapes were compared with those obtained on the cytocentrifuge preparations. Concordant results were obtained in four benign tumours (100%) and 32 malignant tumours (91%). The results obtained by image analysis were also compared with results obtained by flow cytometry of the tumour tissue. Discordant results were obtained for three malignant tumours. Possible reasons for the discrepancy include sampling error, tumour heterogeneity and selective loss of cell populations during processing.

Pulmonary blastoma with germ cell (yolk sac) differentiation: report of two cases

Pulmonary blastoma is a rare lung neoplasm of disputed histogenesis and variable biologic behavior. Typical cases contain both epithelial and mesenchymal tissues, and a variety of patterns of differentiation have been described. While expression of oncofetal antigens in these tumors has been noted rarely, a coexisting component of germ cell tumor has not been reported previously. We describe the clinical and pathologic features of two cases of pulmonary blastoma having alpha-fetoprotein production and histologic areas of yolk sac tumor. We also report the finding of immunohistochemical staining of fetal lung tissue for alpha-fetoprotein.

Effects of nicotine, caffeine, and their combination on locomotor activity in rats

The interactive effect of caffeine and nicotine on spontaneous locomotor activity in a tunnel maze was determined in nicotine-naive and nicotine-tolerant rats. Rats were daily injected subcutaneously for 12 days with nicotine (0.4 mg/kg) to induce nicotine tolerance. Nicotine-naive rats were injected with saline. During the next two days, they were exposed to a tunnel maze for two 6-min trials. On the third day, locomotor activity was measured (30-min trial) in the tunnel maze 15 minutes after subcutaneous injection of saline, nicotine (0.2 mg/kg), caffeine (8 mg/kg), or nicotine (0.2 mg/kg) and caffeine (8 mg/kg) in combination. Acute exposure to nicotine decreased locomotor activity in nicotine-naive rats. This decrease was antagonized by simultaneous injection of caffeine. Chronic nicotine exposure induced the development of tolerance to the acute behavioral depressive effects of nicotine. In nicotine-tolerant rats, caffeine and nicotine in combination significantly increased locomotor activity above saline level, whereas given alone they had no significant stimulant effect. Neither chronic nicotine treatment nor acute drug treatments affected exploratory efficiency of rats.

Perception of affect in patients with dementia of the Alzheimer type

The ability to perceive affect was examined in 19 patients with Alzheimer's disease and in 19 control subjects. Nine tasks were given. All participants were asked to recognize facial emotion, to provide verbal labels of facial emotion, and to identify emotion portrayed in drawings or in verbal descriptions of emotional situations. The results indicate that there are significant differences between patients with Alzheimer's disease and control subjects on all of the tasks. However, when test scores were adjusted for the cognitive abilities of the subjects, few of the tests continue to differentiate the groups. These results suggest that the deficits of patients with Alzheimer's disease on perception of affect tasks are likely to be the result of their cognitive defects and not the result of a primary impairment in the perception of emotion.

[Sex crimes and forensic sexology: analytic study]

Most victims of sexual violence tended to at the IML (Forensic Medicine Institute) are female (94.14%) and predominantly under 18 years of age (72.39%). 60.67% filed a complaint for rape. Out of these cases, 44.63% presented a complete hymen and only in 13.30% of the cases a characterized rape was attested to. 21.38% filed a complaint for seduction. Out of these, 78.05% were between 14 and 18 years of age, and 67.18% of them presented their hymens with non-recent ruptures. In only 9.37% of the complaints for seduction the hymen presented recent ruptures. The cases with complaints of libidinous acts other than carnal conjunction represented 17.95%, predominantly male (56.65%) and under 14 years of age (83.33%). The complaints could be confirmed in only 30% of the cases. 91.83% were anal coitus. As for the time elapsed between the assault and the examination, 11.20% showed up within the first 24 hours; 44.79% within 1 to 7 days; 8.07% within 7 to 15 days and 30.21% after 15 days. In short, just about half of the cases showed up for examination in the first week. Therefore, the authors conclude that there is a low positiveness in the examinations, related to several aspects such as the small percentage of victims that seek the IML in time, the lack of traces, the lack of concepts and the difficulty of conforming the cases to the law.

Semiautomation of preparation of fixed paraffin-embedded tissue for DNA analysis

The usual manual preparation of single-cell suspensions from fixed paraffin-embedded tissue sections for flow cytometric (FCM) DNA ploidy analysis is a time-consuming, labor-intensive technique that requires 70 minutes to deparaffinize and rehydrate 50 microns sections as the initial step. Manual deparaffinization was compared with two semiautomated methods using an automatic slide stainer with either a 70-minute or 35-minute schedule. Samples from 6 normal tissues and 21 tumors (13 diploid and 8 aneuploid) were prepared using all three methods and analyzed by FCM. The mean cell counts in all samples were over 10(6). The DNA indices for the three samples prepared from a given tissue showed no significant differences. Using the 70-minute automation schedule, no aneuploid peaks were lost, and the ratio of G0G1 normal cells to aneuploid tumor cells was maintained. The automation of deparaffinization can thus provide a significant reduction in the labor need to produce single-cell suspensions for FCM; it can be especially helpful when handling large numbers of tumors. At the same time, the automated procedure decreases the exposure to hazardous chemicals and lowers the chance of losing tissue.

Immunohistochemical estrogen receptor assay: quantitation by image analysis

The immunohistochemical estrogen receptor (ER) assay quantitated by image analysis was compared with the biochemical dextran-coated charcoal (DCC) assay in 97 primary breast carcinomas. Frozen sections immunostained for ER with a monoclonal antibody (ER-ICA; Abbott Laboratories, Chicago, IL) and the peroxidase-antiperoxidase technique were scored semiquantitatively by microscopy (HSCORE) and quantitatively [percentage of nuclear area immunopositivity (PNA)] using the CAS 200 image analyzer (Elmhurst, IL). There was a significant and identical correlation between DCC and both HSCORE and PNA. According to sensitivity/specificity calculations, the cut-off points of 10 for HSCORE and 1% for PNA were chosen with positive and negative predictive values of 97.7% and 74.5%, respectively. Low DCC-positive cases between 10 and 50 fmol of ER/mg of protein were immunohistochemically ER positive only in 61.5%. Immunohistochemical results of greater than 150 HSCORE and greater than 15% PNA corresponded to high DCC results of greater than 150 fmol/mg of protein. Immunohistochemical assay quantitated by image analyzer (PNA) is a comparable alternative to biochemical ER, especially when insufficient fresh tissue is available.