Protein folding in the hydrophobic-hydrophilic (HP) model is NP-complete

One of the simplest and most popular biophysical models of protein folding is the hydrophobic-hydrophilic (HP) model. The HP model abstracts the hydrophobic interaction in protein folding by labeling the amino acids as hydrophobic (H for nonpolar) or hydrophilic (P for polar). Chains of amino acids are configured as self-avoiding walks on the 3D cubic lattice, where an optimal conformation maximizes the number of adjacencies between H's. In this paper, the protein folding problem under the HP model on the cubic lattice is shown to be NP-complete. This means that the protein folding problem belongs to a large set of problems that are believed to be computationally intractable.

The prevalence of diabetes in a Swedish population of 280,411 inhabitants. A report from the Skaraborg Diabetes Registry

OBJECTIVE

To estimate the prevalence of known diabetes in a Swedish county (Skaraborg) and to evaluate capture-recapture methods for validation of the diabetes prevalence.

RESEARCH DESIGN AND METHODS

Four sources were used to find known diabetic patients: 1) the Skaraborg Diabetes Registry (SDR), a case-finding inventory, 2) an administrative hospital registry, 3) a registry for the retinopathy screening program, and 4) a pharmacy prescription inventory. The capture-recapture method was applied to various combinations of sources to determine the prevalence of diabetes.

RESULTS

The completeness of the SDR was 88.4 +/- 1.3%, indicating a diabetes prevalence of 3.20 +/- 0.08%. When the SDR was not used as one of the sources, the estimated prevalence varied between 2.2 and 4.5%.

CONCLUSIONS

A case-finding registry is important in reliably estimating the prevalence of diabetes.

Computational learning reveals coiled coil-like motifs in histidine kinase linker domains

The recent rapid growth of protein sequence databases is outpacing the capacity of researchers to biochemically and structurally characterize new proteins. Accordingly, new methods for recognition of motifs and homologies in protein primary sequences may be useful in determining how these proteins might function. We have applied such a method, an iterative learning algorithm, to analyze possible coiled coil domains in histidine kinase receptors. The potential coiled coils have not yet been structurally characterized in any histidine kinase, and they appear outside previously noted kinase homology regions. The learning algorithm uses a combination of established sequence patterns in known coiled coil proteins and histidine kinase sequence data to learn to recognize efficiently this coiled coil-like motif in the histidine kinases. The common appearance of the structural motif in a functionally important part of the receptors suggests hypotheses for kinase regulation and signal transduction.

Primary structure of a copper-binding metallothionein from mantle tissue of the terrestrial gastropod Helix pomatia L

A novel copper-binding metallothionein (MT) has been purified from mantle tissue of the terrestrial snail Helix pomatia using gel-permeation chromatography, ion-exchange chromatography and reverse-phase HPLC. Copper was removed from the thionein by addition of ammonium tetrathiomolybdate. The resulting apothionein (molecular mass 6247 Da) was S-methylated and digested with trypsin, endoproteinase Arg-C and endoproteinase Lys-C. Amino acid sequences of the resulting peptides were determined by collision-induced dissociation tandem MS. The protein is acetylated at its N-terminus, and consists of 64 amino acids, 18 of which are cysteine residues. A comparison with the cadmium-binding MT isolated from the midgut gland of the same species shows an identical arrangement of the cysteines, but an unexpectedly high variability in the other amino acids. The two MT isoforms differ in total length and at 26 positions of their peptide chains. We suggest that the copper-binding MT isoform from the mantle of H. pomatia is responsible for regulatory functions in favour of copper, probably in connection with the metabolism of the copper-bearing protein, haemocyanin.

An iterative method for improved protein structural motif recognition

We present an iterative algorithm that uses randomness and statistical techniques to improve existing methods for recognizing protein structural motifs. Our algorithm is particularly effective in situations where large numbers of sufficiently diverse examples of the motif are not known. These are precisely the situations that pose significant difficulties for previously known methods. We have implemented our algorithm and we demonstrate its performance on the coiled coil motif. We test our program LearnCoil on the domain of 3-stranded coiled coils and subclasses of 2-stranded coiled coils. We show empirically that for these motifs, our method overcomes the problem of limited data.

Retrosplenial/presubicular continuum in primates: a developmental approach in fetal macaques using neurotensin and parvalbumin as markers

In spite of numerous hodological and neuropsychological studies emphasizing the multimodal connections and integrative functions of the retrosplenial cortex in primates, the precise fate of its caudoventral extent and the composition of the merging area with the hippocampal formation remain a matter of debate. We reported previously how the anlage of the retrosplenial cortex merges with the immature presubicular zone in the fetal rhesus monkey at the end of the first trimester of gestation. In the present study, this caudal area was further defined on a chemoarchitectonic basis, particularly during the late prenatal and perinatal stages, which correspond to the development of the cingulate sulcus and temporal gyri, and the differentiation of the retrosplenial/subicular complex. Neurotensin (NT), a pyramidal cell marker in the limbic cortex, and parvalbumin (PV), a marker of a subset of inhibitory local circuit neurons in the hippocampal formation, were used as immunocytochemical markers. According to distinct chemoarchitectural patterns, (1) areas 29 l and 29 m of the retrosplenial cortex formed a triangle-shaped ventral expansion which merged with a similar but dorsal expansion of the pre/parasubicular fields. A temporal extension of area 29 m down to area TH could not be detected. The pre/parasubiculum contributed with area 29 m to the lateral bank of the calcarine sulcus as far as the most caudal extent of the hippocampal formation. (2) The lamina principalis interna of the presubiculum was well individualized and did not appear as a simple horizontal shift of adjoining fields. (3) NT and PV displayed a distinct temporal profile of development. NT was already expressed in the pyramidal cells of the prospective retrosplenial cortex and ventral hippocampal formation at E47 (term 165 days). Major pathways of the hippocampal formation and retrosplenial cortex (fimbria, fornix, angular and cingulum bundles) were progressively labeled indicating early developing projections. A large set of NT-positive afferents reached the retrosplenial cortex between E114 and E120. Their laminar distribution was compatible with a thalamic or a subicular origin. (4) The development of PV expression was delayed until the last quarter of gestation, supporting its proposal as a signal of functional onset. The developmental fate and the particular connections of the presubiculum suggest that its functional importance should be further investigated during infancy and adulthood.

MultiCoil: a program for predicting two- and three-stranded coiled coils

A new multidimensional scoring approach for identifying and distinguishing trimeric and dimeric coiled coils is implemented in the MultiCoil program. The program extends the two-stranded coiled-coil prediction program PairCoil to the identification of three-stranded coiled coils. The computations are based upon data gathered from a three-stranded coiled-coil database comprising 6,319 amino acid residues, as well as from the previously constructed two-stranded coiled-coil database. In addition to identifying coiled coils not predicted by the two-stranded database programs, MultiCoil accurately classifies the oligomerization states of known dimeric and trimeric coiled coils. Analysis of the MultiCoil scores provides insight into structural features of coiled coils, and yields estimates that 0.9% of all protein residues form three-stranded coiled coils and that 1.5% form two-stranded coiled coils. The MultiCoil program is available at http:/(/)theory.lcs.mit.edu/multicoil.

Simple method for simultaneous determination of halothane, enflurane, and isoflurane in Krebs solution using capillary gas chromatography

A simple gas chromatography (GC) method for the simultaneous determination of halothane, enflurane, and isoflurane in Krebs buffer solution has been developed. The method utilizes methylene chloride as the internal standard and liquid-liquid extraction using chloroform as the solvent. The method demonstrated excellent recovery (100%) of each component and a linear calibration range of 100-700, 100-800, and 300-1,400 micrograms/mL for halothane, isoflurane, and enflurane, respectively. Intra-day accuracy and precision had an error and coefficient of variation of less than 5.1% and 2.7%, respectively.

Pharmacological and toxicological aspects of new imidazoacridinone antitumor agents

Imidazoacridinones represent a new group of antitumor compounds developed by J. Konopa and coworkers in Gdansk, Poland (W.M. Cholody, J. Med. Chem., 33: 49-52, 1990). The compounds exert activity against a broad spectrum of human tumors in the National Cancer Institute in vitro screening scheme. In this work, the in vitro cytotoxicity, cellular pharmacology, and genotoxic/transforming potential of five selected imidazoacridinones were studied. The compounds were highly cytotoxic (0.01-0.40 microM) to dividing cells, such as Friend erythroleukemia cells (line F4-6), V79 Chinese hamster cells, and exponentially growing C3H/M2 mouse fibroblasts. In contrast, nondividing primary rat hepatocytes and C3H/M2 cells in confluency were less sensitive to the toxicity of the imidazoacridinones. Multidrug-resistant-overexpressing F4-6 cells, 200-fold resistant to doxorubicin, showed only partial resistance (4-10 fold) to the imidazoacridinones. The cellular transport of the fluorescent imidazoacridinones occurred rapidly, and most of the drug fluorescence was localized in the nucleus. Cellular accumulation and retention of two selected imidazoacridinones (C-1310 and C-1311) in sensitive as well as in resistant F4-6 cells were determined with laser-excited flow cytometry. After an incubation with C-1311 and C-1310 for 60 min at 37 degrees C, the cellular accumulation of the less cytotoxic compound C-1310 was greater than that of C-1311, and for both compounds, the fluorescence in the resistant F4-6 cells was one-half of that in the sensitive F4-6 cells. Lowered temperature (4 degrees C) reduced the cellular accumulation for both compounds in the sensitive and in the resistant F4-6 cells and was comparable to the uptake in resistant F4-6 cells. The treatment of the resistant F4-6 cells with the multidrug-resistant modulator verapamil led to an enhanced accumulation of C-1310 and C-1311 by the cells. All five compounds produced a dose-dependent inhibition of [3H]uridine and [14C]thymidine incorporation and, except for C-1336, preferentially inhibited DNA synthesis. The affinity of the imidazoacridinones to DNA is also indicated by an increase of the DNA melting point by 9-11 degrees C. The mutagenic potential of the imidazoacridinones was investigated in the hypoxanthine guanine phosphoribosyl transferase test; the compounds C-1310 and C-1311 were additionally tested in the Salmonella typhimurium-microsome assay. Limited mutagenicity was detected in the hypoxanthine guanine phosphoribosyl transferase test, and in Salmonella typhimurium, mutagenicity was observed only in the strain TA1537. Furthermore, no induction of DNA repair synthesis was observed after treatment of primary hepatocytes with the five imidazoacridinones. The compounds did not transform C3H/M2 fibroblasts. One derivative, C-1336, led to a significant induction of cell differentiation in Friend erythroleukemia cells. The results of this study show that the imidazoacridinones display a strong cytotoxic effect in rapidly dividing cells and only a partial resistance toward multidrug resistant cells; in addition, they showed a limited mutagenic potential in V79 fibroblasts and Salmonella typhimurium and no transforming potential in C3H/M2 cells. The imidazoacridinones are, therefore, an interesting group of new antitumor agents, and further in vivo studies are warranted to explore the usefulness of these compounds for the treatment of human cancer.

Motility of spermatozoa ofAlburnus alburnus (Cyprinidae) and its relationship to seminal plasma composition and sperm metabolism

The composition of seminal plasma and metabolism of sperm of the cyprinid fishAlburnus alburnus were investigated. Statistically significant correlations were found between motility parameters and seminal fluid osmolality, pH, Na(+), K(+) and protein levels (negative correlations: % immotile spermatozoa-Na(+), K(+); positive correlations: % motile spermatozoa-osmolality, pH, Na(+), K(+), protein; % linear motile spermatozoa-pH protein; swimming velocity of spermatozoa-pH, Na(+), protein). Spermatozoan motility and ATP metabolism and glycolysis were correlated as indicated by measurement of ATPase, pyruvate kinase, adenylate kinase and lactate dehydrogenase activity. The physiological meanings of these correlations and their possible significance for quality control of semen are discussed.

Neurochemical development of the hippocampal region in the fetal rhesus monkey, III: calbindin-D28K, calretinin and parvalbumin with special mention of cajal-retzius cells and the retrosplenial cortex

In spite of continuing controversy on the precise function of the calcium-binding proteins expressed in the hippocampal formation, nothing is known about their prenatal development in primates. In this study, calbindin-D28K, calretinin, and parvalbumin were localized in the hippocampal formation of seven rhesus monkey fetuses aged E47 to E90 (term 165 days). All of the three markers were expressed during the first half of gestation in distinct subsets of nonpyramidal neurons: calretinin-containing cells were the most numerous and relatively differentiated contrasting with a more restricted, less mature, parvalbumin-labeled population and a poor calbindin-positive nonpyramidal contingent. The granule cells and pyramidal neurons were calbindin-positive, including the pyramids of CA3 and the subicular complex, in contrast to the situation found in the adult monkey. The presubiculum and retrosplenial cortex, whose merging formed the caudal pole of the hippocampal formation, also expressed precociously the three calcium-binding proteins. A heterogeneous population of Cajal-Retzius-like cells was demonstrated in the marginal zone of the ventral hippocampal formation. The majority co-expressed calbindin-D28K and calretinin and displayed acetylcholinesterase activity but no GABA-like immunoreactivity. Major intrinsic and extrinsic pathways of the hippocampal system (mossy fiber system, alveus, fimbria, angular, and cingular bundles) were immunoreactive for calretinin and/or calbindin. The distinct developmental time course and regional pattern of distribution of calbindin-D28K, calretinin, and parvalbumin in the nonprincipal neurons suggests a precocious but asynchronous prenatal development of different inhibitory circuits in the hippocampal formation of primates. The labeling of several fiber systems in keeping with comparable early events in the entorhinal cortex (Berger et al.: Hippocampus 3:279-305, 1993), suggests the possibility of earlier functional circuits than hitherto inferred from the observations available in rodents, a hypothesis that deserves further investigation.

Evidence for more extensive deposits of epitopes of oxidized low density lipoprotein in aortas of young people with elevated serum thiocyanate levels. PDAY Research Group

Elevated levels of low density lipoprotein (LDL) and smoking have long been recognized as risk factors for atherosclerosis and coronary heart disease (CHD). However, the mechanisms by which these factors contribute to the disease have not been fully elucidated. It has been postulated from in vitro studies using serum and LDL from smokers that smoking increases the oxidation of LDL, which in turn contributes to atherogenesis. We know of no direct evidence linking oxidized LDL (oxLDL) in human arteries to increased atherosclerosis in individuals who show elevated serum thiocyanate levels (HST) as an indicator of recent smoking. We have studied arterial samples from smokers micromorphometrically and found that 'smokers' have a greater area in which oxLDL can be identified in the early stages of the disease than do "nonsmokers', i.e., individuals with low serum thiocyanate levels (LST). This study demonstrates a positive correlation between the extent of oxLDL in the fatty streaks as well as the fatty plaques of standardized core sample areas of the thoracic and abdominal aortas of a sample group of young people, aged 15-34, who have evidence of recent smoking based on their postmortem serum thiocyanate levels.

An impedance index in normal subjects and in subarachnoid hemorrhage

The impedance of a hemodynamic system is defined as the ratio of each harmonic component of blood pressure to that of flow. Calculation of impedance cures has been extensively performed in the systemic circulation, leading to the recognition of reflected pressure and flow waves and clarifying the shape of ultrasound waveforms. Impedance in the human cerebral circulation has not been measured primarily because of the relative inaccessibility of simultaneous flow and pressure data in the human cerebral circulation. We defined an impedance index using the transcranial Doppler waveform for that of flow and a noninvasive applanation measure of the carotid artery pressure waveform. Middle cerebral artery velocities and carotid artery pressure waveforms were simultaneously recorded in 16 vessels from 10 normal volunteers, 42 vessels in 14 patients with aneurysmal subarachnoid hemorrhage, and 14 vessels in 7 subjects during conditions of hypocapnia, normocapnia and hypercapnia. Impedance was calculated by dividing the harmonic associated with pressure divided by that of flow, and averaging 10 to 20 such calculations. Relative impedance curves were calculated by dividing by the impedance at the first harmonic. Impedance was also studied in an electrical model consisting of a Windkessel element containing inductance in series with a second Windkessel to model the large vessel and vascular bed, respectively. Model parameters were taken from the literature for these calculations. For the normal subjects, the shape of the impedance index curve was similar to those found in the systemic circulation. The impedance index curves for patients in vasospasm (middle cerebral velocity was greater than 180) showed a peak at the second or third harmonic, which appeared more frequently than the nonspasm group (p < 0.01). Furthermore, the ratio of the second harmonic to the first harmonic was significantly > 1.0 in the spasm group but significantly < 1.0 in the normal group (p < 0.05). Calculations from the electrical model replicated the appearance of these peaks at the second or third harmonic for vasospasm parameters. A statistically significant peak appeared at the second or third harmonic in the impedance index curves for patients in vasospasm, which was replicated quantitatively by our electrical model. Although such peaks can be explained in the systemic circulation by the presence of reflected waves, the distance to the reflection site is larger than expected for the cerebral circulation. This suggests the importance of the inertia of blood as a stenosis worsens and as the origin for the observed changes in the impedance index curves.

Mass spectrometry and amino acid sequencing of two cadmium-binding metallothionein isoforms from the terrestrial gastropod Arianta arbustorum

1. Two cadmium-binding metallothionein (Mt) isoforms, called Mta and Mtb, were isolated from terrestrial snails (Arianta arbustorum), using various chromatographic techniques, such as gel-permeation chromatography and reversed-phase HPLC. The purified proteins were S-methylated and cleaved by means of different enzymes (trypsin, endoproteinase Glu-C, and endoproteinase Asp-N). Amino acid sequences were determined by automated Edman degradation and collision-induced dissociation (CID) tandem MS. According to their primary structures, both isoforms should be attributed to class-I Mts. 2. The two forms are structurally identical, differing only by one amino acid exchange in position 60 of the peptide chain. Both isoproteins consist of 66 amino acids, 18 of which are cysteine residues. Most of the cysteine residues are arranged in seven Cys-Xaa-Cys motifs. Mta and Mtb possess an N-terminal acetylated-serine residue and contain a short N-terminal motif which shows a high degree of similarity with the N-termini of histones H4 and H2A. 3. A comparison of Mta and Mtb with other invertebrate Mts shows a very high degree of sequence similarity with a cadmium-binding Mt from Helix pomatia, a species that is closely related to Arianta arbustorum. Moreover, Mta and Mtb, as expected, also exhibit structural similarities with Mts from other molluscan species, such as mussels and oysters. It is suggested that Mta and Mtb represent two allelic isoforms, reflecting the genetic polymorphism of Mt in Arianta arbustorum.

Predicting coiled coils by use of pairwise residue correlations

A method is presented that predicts coiled-coil domains in protein sequences by using pairwise residue correlations obtained from a (two-stranded) coiled-coil database of 58,217 amino acid residues. A program called PAIRCOIL implements this method and is significantly better than existing methods at distinguishing coiled coils from alpha-helices that are not coiled coils. The database of pairwise residue correlations suggests structural features that stabilize or destabilize coiled coils.

Validity of three clinical performance assessments of internal medicine clerks

PURPOSE

To analyze the construct validity of three methods to assess the clinical performances of internal medicine clerks.

METHOD

A multitrait-multimethod (MTMM) study was conducted at the Case Western Reserve University School of Medicine to determine the convergent and divergent validity of a clinical evaluation form (CEF) completed by faculty and residents, an objective structured clinical examination (OSCE), and the medicine subject test of the National Board of Medical Examiners. Three traits were involved in the analysis: clinical skills, knowledge, and personal characteristics. A correlation matrix was computed for 410 third-year students who completed the clerkship between August 1988 and July 1991.

RESULTS

There was a significant (p < .01) convergence of the four correlations that assessed the same traits by using different methods. However, the four convergent correlations were of moderate magnitude (ranging from .29 to .47). Divergent validity was assessed by comparing the magnitudes of the convergence correlations with the magnitudes of correlations among unrelated assessments (i.e., different traits by different methods). Seven of nine possible coefficients were smaller than the convergent coefficients, suggesting evidence of divergent validity. A significant CEF method effect was identified.

CONCLUSION

There was convergent validity and some evidence of divergent validity with a significant method effect. The findings were similar for correlations corrected for attenuation. Four conclusions were reached: (1) the reliability of the OSCE must be improved, (2) the CEF ratings must be redesigned to further discriminate among the specific traits assessed, (3) additional methods to assess personal characteristics must be instituted, and (4) several assessment methods should be used to evaluate individual student performances.

Algorithms for protein structural motif recognition

The identification of protein sequences that fold into certain known three-dimensional (3D) structures, or motifs, is evaluated through a probabilistic analysis of their one-dimensional (1D) sequences. We present a correlation method that runs in linear time and incorporates pairwise dependencies between amino acid residues at multiple distances to assess the conditional probability that a given residue is part of a given 3D structure. This method is generalized to multiple motifs, where a dynamic programming approach leads to an efficient algorithm that runs in linear time for practical problems. By this approach, we were able to distinguish (2-stranded) coiled-coil from non-coiled-coil domains and globins from nonglobins. When tested on the Brookhaven X-ray crystal structure database, the method does not produce any false-positive or false-negative predictions of coiled coils.

Using lod-score differences to determine mode of inheritance: a simple, robust method even in the presence of heterogeneity and reduced penetrance

Determining the mode of inheritance is often difficult under the best of circumstances, but when segregation analysis is used, the problems of ambiguous ascertainment procedures, reduced penetrance, heterogeneity, and misdiagnosis make mode-of-inheritance determinations even more unreliable. The mode of inheritance can also be determined using a linkage-based method (maximized maximum lod score or mod score) and association-based methods, which can overcome many of these problems. In this work, we determined how much information is necessary to reliably determine the mode of inheritance from linkage data when heterogeneity and reduced penetrance are present in the data set. We generated data sets under both dominant and recessive inheritance with reduced penetrance and with varying fractions of linked and unlinked families. We then analyzed those data sets, assuming reduced penetrance, both dominant and recessive inheritance, and no heterogeneity. We investigated the reliability of two methods for determining the mode of inheritance from the linkage data. The first method examined the difference (delta) between the maximum lod scores calculated under the two mode-of-inheritance assumptions. We found that if delta was > 1.5, then the higher of the two maximum lod scores reflected the correct mode of inheritance with high reliability and that a delta of 2.5 appeared to practically guarantee a correct mode-of-inheritance inference. Furthermore, this reliability appeared to be virtually independent of alpha, the fraction of linked families in the data set, although the reliability decreased slightly as alpha fell below .50.(ABSTRACT TRUNCATED AT 250 WORDS)

Local rule-based theory of virus shell assembly

A local rule-based theory is developed which shows that the self-assembly of icosahedral virus shells may depend on only the lower-level interactions of a protein subunit with its neighbors--i.e., on local rules rather than on larger structural building blocks. The local rule theory provides a framework for understanding the assembly of icosahedral viruses. These include both viruses that fall in the quasiequivalence theory of Caspar and Klug and the polyoma virus structure, which violates quasi-equivalence and has puzzled researchers since it was first observed. Local rules are essentially templates for energetically favorable arrangements. The tolerance margins for these rules are investigated through computer simulations. When these tolerance margins are exceeded in a particular way, the result is a "spiraling" malformation that has been observed in nature.

Neurochemical development of the hippocampal region in the fetal rhesus monkey. II. Immunocytochemistry of peptides, calcium-binding proteins, DARPP-32, and monoamine innervation in the entorhinal cortex by the end of gestation

Material for the study came from one 126 day-old rhesus monkey fetus and two 3 day-old neonates. The immunocytochemical detection of somatostatin, neurotensin (NT), parvalbumin, calbindin D-28K, DARPP-32 as well as tyrosine hydroxylase (TH), dopamine-beta-hydroxylase and serotonin (5-HT), was carried out on serial cryostat sections of the entorhinal cortex. The authors reported in a previous paper the precocious differentiation of the entorhinal cortex in rhesus monkey fetuses and featured the conspicuous expression of calbindin D-28K, somatostatin, neurotensin, and the monoaminergic innervation during the first half of gestation. The present study shows distinct temporal profiles of neurochemical development during the second half of gestation: the dense neuropeptidergic innervation remained a constant feature; the three aminergic systems gradually increased in density; parvalbumin, unlike calbindin D-28K, was primarily expressed during the last quarter of gestation. Three other prominent features of the last quarter of gestation are illustrated: the refinement of the modular neurochemical organization of the lamina principalis externa, the delayed chemoanatomical development of the rhinal sulcus area, and the establishment of a distinct rostrocaudal pattern of neurochemical distribution. In correspondence with the cluster-like organization of the lamina principalis externa, the authors observed in the olfactory, rostral, and intermediate fields of the neonate monkey entorhinal cortex, a particular subset of pyramidal-shaped neurons: located in layer III, they were characterized by fasciculated apical dendrites ascending between the cellular islands of the discontinuous layer II and the coexpression of calbindin D-28K and DARPP-32. Besides, most of the other chemical systems displayed a distinct, area-specific, patchy distribution, except for the homogeneously distributed noradrenergic innervation. In the olfactory and rostral fields, TH positive dopaminergic fibers accumulated on the neuronal islands of layers II-III, and parvalbumin labeled fibers on those of layer III, whereas patches of 5-HT and NT-like reactive terminals were segregated between the cellular islands, overlapping the DARPP-32/calbindin D-28 K labeled dendritic bundles. At the opposite, in the intermediate field, 5-HT positive terminals overlapped the cellular islands of layer II and thin fascicles of dopaminergic fibers ran in the inter island spaces. The somatostatin-LIR innervation was apparently too dense to reveal a patchy distribution that existed at earlier developmental stages. In the caudal field, the patchy pattern was replaced by a predominant bilaminar type of distribution of NT, 5-HT, and TH-like positive afferents.(ABSTRACT TRUNCATED AT 400 WORDS)

Glucocorticoid-mediated inhibition of interleukin-2 receptor alpha and -beta subunit expression by human T cells

To determine the mechanism of glucocorticoid (GC)-mediated inhibition of T cell functions, the effect of dexamethasone (DM) on T cell proliferation and interleukin-2 receptor (IL-2R) generation were studied. Dexamethasone inhibited IL-2-induced T cell proliferation by 30%-88%, relative to its concentration within the cultures. The effect of DM on expression of IL-2R alpha (Tac, p55, CD25) and beta (p75) genes in activated T cells was examined next. In T cells stimulated with purified phytohemagglutinin (PHA-p) and 4 beta-phorbol 12-myristate 13-acetate (PMA) addition of DM to the cultures resulted in a 60% reduction in IL-2R alpha and a 30% reduction in IL-2R beta membrane expression compared to T cells cultured in the absence of DM (p < 0.01). Inhibition of membrane IL-2R alpha and IL-2R beta expression by 10(-6) M DM was partially reversible by recombinant human IL-2 (rhIL-2). By Northern blot analysis, DM caused a comparable decrease in IL-2R alpha and in IL-2R beta mRNA levels to membrane receptor expression in mitogen-stimulated T cells. By in vitro transcription assays, DM regulated IL-2R alpha gene expression at a transcriptional level while transcription of IL-2R beta gene was unaffected by DM. The mechanism of action of DM on IL-2R alpha transcription was examined by determining the mRNA levels of the p50 subunit of nuclear factor kappa B (NF-kappa B), a transcription factor that stimulates IL-2R alpha gene expression. The data indicate that 10(-6) M DM increased T cell p50 NF-kappa B mRNA levels by four-fold compared to the levels obtained in the absence of DM. Further, the level of nuclear proteins capable of binding to the NF-kappa B sites in activated T cells increased in response to DM. In sum, DM regulates T cell membrane expression of IL-2R by more than one molecular mechanism.

Immunocytochemical evidence of well-developed dopaminergic and noradrenergic innervations in the frontal cerebral cortex of human fetuses at midgestation

The catecholaminergic (CA) innervation of the frontal lobe was visualized in 20- to 24-week-old human fetuses with immunocytochemical techniques, by use of antibodies raised against three synthetic enzymes of the CA pathway, tyrosine-hydroxylase (TH), dopamine-beta-hydroxylase (DBH), and phenylethanolamine-N-methyltransferase (PNMT). DBH-like immunoreactivity (IR) was probably labeling the noradrenergic (NA) fibers and terminals in the cerebral cortex since no PNMT-IR fibers were detected. In double-labeling TH-DBH experiments, 92-95% of the DBH-IR afferents were not labeled with TH antibodies, indicating that TH-like immunoreactivity (TH-IR) was found primarily in dopaminergic (DA) fibers. Although cortical layering had not yet occurred at this stage, the widespread CA innervation observed in the different areas and layers of the fetal frontal cortex was comparable to that previously described in the adult (Gaspar, Berger, Febvret, Vigny, and Henry: J. Comp. Neurol. 279:249-271, '89). At midgestation, the distribution of CA innervation was region and laminar specific: 1) The densest dopaminergic innervation in the cerebral cortex was located caudal to the genu of the corpus callosum: TH-IR fibers were abundant throughout all layers, from the medial telencephalon (future cingulate) to the dorsal areas (presumed motor cortices) and the lateral insular areas; 2) TH-IR fibers were less dense in the rostral prefrontal cortical anlage; 3) DBH-IR noradrenergic afferents were less numerous than the dopaminergic ones in all the cortical areas studied; 4) in all areas, the highest amount of TH and DBH-IR terminals was found in the upper subplate and in the lower part of the cortical plate, followed by the molecular layer and the intermediate zone. The deep subplate exhibited a lower number of positive fibers but contained TH-IR cell bodies. The presence of dense CA innervation in the immature cortical anlage of the human frontal lobe does not exclude a reorganization of DA and NA innervations within the different cortical layers and areas during the protracted pre- and postnatal period of development.

[Evaluation of platelet function during treatment with recombinant human erythropoietin (r-HuEPO) in patients hemodialyzed and dialyzed peritoneally]

In eight patients with terminal renal insufficiency treated with repeated haemodialyses (group I) and six patients treated with intermittent peritoneal dialysis (group II), the effect was studied of treatment with r-HuEPO on the platelet count and activity. In the studied patients the following was determined: platelet count, ADP-induced aggregation, circulating aggregates, and the third (PF3) and fourth (PF4) platelet factors. The studies were performed before the introduction of r-HuEPO and during the treatment--after achieving of haematocrit increase in the patients to 30%. No significant increase was observed of platelet count or activity. In none of the studied patients the development of thrombotic complications was observed with haematocrit increase to 30%. In both studied groups during the treatment with r-HuEPO a significant increase was found of haemoglobin concentration, red blood cell count, and haematocrit value in relation to the values before starting the treatment.

Purification and primary structure of snail metallothionein. Similarity of the N-terminal sequence with histones H4 and H2A

A cadmium-binding metallothionein has been purified from metal-exposed Roman snails (Helix pomatia) using gel-permeation, ion-exchange and reverse-phase high-performance liquid chromatography. The S-methylated protein was digested with trypsin and the endoproteinases Asp-N, Glu-C and Arg-C. While most of the resulting peptides could be sequenced by Edman degradation, the intact protein, as well as the N-terminal peptide, proved to be blocked. Analysis by mass spectrometry showed that the N-terminal amino acid was an acetylated serine residue. Snail metallothionein, which is suggested to be involved in the detoxification of cadmium, contains 66 amino acid residues, 18 of which are cysteine residues arranged in seven Cys-Xaa-Cys motifs. The calculated molecular mass of the protein is 6.62 kDa. The primary structure of snail metallothionein reveals a clear relationship with molluscan and vertebrate metallothioneins, but lower similarity with metallothioneins of other invertebrate species. The N-terminal region of the isolated protein proved to be unique among the metallothionein sequences determined so far, showing high degrees of similarity with the N-terminal sequences of histones H2A and H4 which may be important for regulatory functions.

Neurochemical development of the hippocampal region in the fetal rhesus monkey. I. Early appearance of peptides, calcium-binding proteins, DARPP-32, and monoamine innervation in the entorhinal cortex during the first half of gestation (E47 to E90)

Although the entorhinal cortex is a key structure connecting the hippocampal formation with the rest of the cerebral cortex, little is known about its early chemoanatomical development in primates. In the present study, a cytoarchitectonic analysis and immunocytochemical detection of somatostatin, neurotensin, parvalbumin, calbindin-D 28K, DARPP-32, as well as tyrosine hydroxylase, dopamine-beta-hydroxylase, and serotonin, were carried out on serial sections of the entorhinal cortex of six rhesus monkey fetuses aged E47 to E90 (gestation period 165 days). At E56 the cortical plate of the entorhinal cortex already exhibited a sublamination; at E64 the lamina dissecans was partly formed, allowing the emergence of the lamina principalis externa and interna, and at E83 most of the regional and laminar subdivisions characteristic of the adult cortex could be identified, except for the rhinal sulcus restricted to a small dimple. The neurochemical development paralleled the early cytoarchitectonic differentiation, both largely preceding that of the neighboring cortical areas. The somatostatin-like immunoreactive innervation, first detected at E56, was very dense as early as E64 and displayed by E83 a laminar distribution similar to that found in the adult. Labeled neurons indicated an intrinsic origin for this innervation but an extrinsic connection might be present as labeled fibers in the subplate of the entorhinal cortex were in continuity with positive fibers in the intermediate zone of the hippocampal formation. A faint neurotensin-like immunoreactivity first detected at E64 became prominent at E83 in the entorhinal cortex but stopped abruptly at the anlage of the rhinal sulcus. The lack of neurotensin-labeled neurons contrasted with their presence in other parts of the hippocampal region and suggested a precocious extrinsic connection. Only rare parvalbumin-LIR neurons were detected at midgestation, whereas calbindin-D 28K was expressed from E47 on in Cajal-Retzius cells and from E56 on in various types of neurons in the cortical plate and subplate. Most characteristic was a category of medium-sized, deeply stained calbindin-LIR neurons, present only in the lamina principalis externa and possibly corresponding to the population of large neurons described by Kostovic et al. (1990, Soc Neurosci Abstr 16:846) in early developing entorhinal cortex of human fetuses. These and probably other neurons were also DARPP-32-positive, suggesting the possibility of an early dopaminergic regulation. Indeed, the monoaminergic innervation of the entorhinal cortex was detected from E56 on and gradually increased in density, displaying areal and laminar differences in the distribution of the dopaminergic, noradrenergic, and serotoninergic afferents.(ABSTRACT TRUNCATED AT 400 WORDS)

Terrestrial snails as quantitative indicators of environmental metal pollution

Concentrations of cadmium, lead, copper and zinc were measured in individuals of Arianta arbustorum from different urban sampling sites. In comparison to snails from a reference site, the animals collected in the city showed higher concentrations of cadmium, lead, and copper, indicating elevated levels of metal pollution. The most pronounced difference in tissue concentrations between control animals and contaminated snails was observed for lead. Within the city, metal levels in snails differed significantly, even between adjacent populations. Arianta arbustorum is a suitable species for biomonitoring, because it is widespread, resident and easy to collect; it has a high capacity for metal accumulation and shows different concentrations depending on metal contamination of the sampling area. An interspecific comparison of metal concentrations in terrestrial gastropods was conducted to define background levels and classes of burden. Three pollution levels are distinguished on the basis of the snails' metal burden: no pollution (class 1: reference sites), moderate (class 2: traffic and other human activities in urban areas), and high pollution (class 3: mining and heavy industry).

A new look at cervical cytology. ThinPrep multicenter trial results

The objective of this study was to compare the sensitivity of a new test method with the smear method for detection of neoplasia of the uterine cervix. The new procedure, the ThinPrep process, is an automated, fluid-based technique for the collection and preparation of exfoliated and aspirated cytologic specimens. A single sample from each patient was split and prepared both with the smear and test methods. The diagnostic results from the two slides were compared in this blind study. Among a total of 2,655 patients, diagnoses concurred in 92% of cases and were within one diagnostic level of each other 98% of the time. The ThinPrep method facilitated the detection of more low-grade lesions (P less than .001, McNemar's test). In addition, the test method decreased the number of ambiguous interpretations. The ThinPrep method appears to improve the cervical cytologic smear quality by the harvest of a random and reproducible sample, with a reduction in artifacts. The new method improves the sensitivity of the cervical cytologic screening test.

Shedding of a rhinovirus minor group binding protein: evidence for a Ca(2+)-dependent process

Soluble rhinovirus minor group binding activity was found to be shed into the medium upon incubation of HeLa cells at 37 degrees C. Although substantial amounts of this protein were released, no decrease of virus binding to the cell surface was seen. When the membrane-associated receptor was stripped from the cells with trypsin, virus binding was rapidly restored from an intracellular pool even in the absence of de novo protein synthesis. The release of this 85K virus-binding activity was inhibited by metal chelators such as EDTA, EGTA or 1,10-phenanthroline. The potential involvement of a Ca(2+)-dependent protease and/or a phospholipase in this process is discussed.

Superior orbicularis oris muscle activity in children with and without cleft lip and palate

An analysis of integrated electromyographic (IEMG) activity of the superior orbicularis oris muscle was undertaken in 15 children with cleft lip and palate who have undergone surgery compared to 10 children without clefts (control group). Bipolar surface electrodes were used for IEMG recordings of resting level activity and during the swallowing of saliva. Similar resting level activity was observed in both groups. During the swallowing of saliva, activity in children with cleft lip and palate was higher than in children without clefts (noncleft children). Moreover, in the cleft lip and palate group, children with abnormal lip seal showed the highest values for IEMG activity during the swallowing of saliva. This fact suggests that with each swallow of saliva, a greater counteracting effect of the superior orbicularis oris muscle could be produced on the growing maxilla. This may result in a significant long-term effect on the growth of the stomatognathic system, since the process of swallowing is a 24-hour function repeated between 600 and 2400 times each day.

Placental mosaicism in a case of 46,XY,-22,+t(22;22)(p11;q11) or i(22q) diagnosed at amniocentesis

46,XY,-22,+t(22;22)(p11;q11) or i(22q) was diagnosed in 15/15 cells from two cultures from the amniotic fluid culture of a 31-year-old patient whose fetus demonstrated cystic hygroma on ultrasound. Cytogenetic studies performed on fetal skin from the abortus revealed the same karyotype as that seen on amniocentesis, but the placenta demonstrated a 46,XY/46,XY,-22,+t(22;22) or i(22q) mosaicism, with 65 per cent of the cells being 46,XY. This case provides an example of placental mosaicism for a normal male karyotype, while the fetus demonstrated non-mosaic trisomy 22.

Early evidence of catecholaminergic cell groups in 5- and 6-week-old human embryos using tyrosine hydroxylase and dopamine-beta-hydroxylase immunocytochemistry

Catecholaminergic systems were visualized in the CNS of human embryos from stage 15-16 (5 gestational week, g.w.) to 18 (6 g.w.) using tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) as immunocytochemical markers. At 5 g.w., several TH-like immunoreactive (TH-IR) cell groups were identified in the medulla oblongata, pons, mesencephalon and the anlage of the hypothalamic area. DBH immunoreactivity was restricted to the locus coeruleus and to rare neurons in the medulla oblongata. At 6 g.w., the density of TH-IR neurons was strikingly increased in these different areas--especially in the prospective substantia nigra and ventral tegmental area--and two main bundles of catecholaminergic axons extended from the medulla oblongata until the basal forebrain and from the mesencephalic tegmentum to the anlage of the striatum. These pathways were mainly TH-IR but DBH-IR was also observed in the former. No TH-IR fibers reached the telencephalon at 6 g.w.

Alterations of dopaminergic and noradrenergic innervations in motor cortex in Parkinson's disease

The motor areas of the cerebral cortex contain dense dopaminergic and noradrenergic innervation in humans. We looked for changes of these innervations in cases with Parkinson's disease (PD). The density of fibers immunolabeled with tyrosine hydroxylase or dopamine-beta-hydroxylase was evaluated in the primary motor, premotor, and prefrontal cortical regions in 6 cases with PD and 7 control cases. Reductions of both noradrenergic and dopaminergic cortical innervations were observed, with similar magnitudes of reduction found in the motor and prefrontal regions of the cortex. Depletion of noradrenergic innervation was diffuse, involving all cortical laminae. Depletion of dopaminergic innervation was laminar specific, with the most significant reductions in layers I and II; reductions in layers V and VI were either less marked (prefrontal cortex) or not detectable (primary motor). The results suggest the existence of two separate mesocortical dopaminergic systems in humans, with the one distributing to upper cortical layers being preferentially involved in PD.

Further indication that distinct dopaminergic subsets project to the rat cerebral cortex: lack of colocalization with neurotensin in the superficial dopaminergic fields of the anterior cingulate, motor, retrosplenial and visual cortices

The extent of neurotensin (NT) colocalization in the different dopamine (DA) terminal fields of the rat cerebral cortex has been investigated and compared to previous data obtained in man (Gaspar et al., J. Comp. Neurol., 279 (1989) 249-271). Both innervations were revealed with single- or double-labeling immunocytochemical methods. Tyrosine hydroxylase (TH) was used as a specific marker of DA fibers after lesioning the noradrenergic system either with 6-hydroxydopamine (6-OHDA) at birth or DSP4 in adulthood. Three classes of afferents were observed which had a different regional and laminar distribution. First, a dense meshwork of finely dotted NT-positive varicosities occupied restricted areas of the limbic system: the granular retrosplenial and the deep entorhinal cortices and the subicular complex. These NT projections contained no double-labeled fibers and did not correspond to a mixed NT/TH pathway. Secondly, the mixed NT/DA projections identified previously in the prefrontal cortex (Studler et al., Neuropeptides, 11 (1988) 95-100), extended in fact rostrocaudally in layer VI of the whole cerebral cortex and formed small cluster-like groupings in layers II-III of the medial and lateral entorhinal cortex. In all these areas, the mixed NT/TH projections constituted approximately half of the DA terminals. Finally, the DA projections to the superficial layers of the anterior cingulate, motor, retrosplenial and visual cortices, were not colocalized with NT. The DA innervation of layers I-III of the rat anterior cingulate cortex displays striking similarities with that observed in the cingulate, primary motor, premotor and supplementary motor cortices in man: highest regional and laminar density of DA afferents and lack of colocalization with NT. It might thus represent a valuable model for understanding the pharmacology of the DA system besides the mixed DA/NT pathway which does not seem to have a counterpart in the human cerebral cortex. By contrast, that part of the NT innervation of the limbic system which is not colocalized with DA in rat, appears to represent the major fraction of the cortical NT innervation in man.

Brefeldin A induces endoplasmic reticulum-associated O-glycosylation of galactosyltransferase

Recent data from several laboratories show that Brefeldin A (BFA) induces a microtubule-dependent back-flow of Golgi components to the endoplasmic reticulum (ER) thereby causing disassembly of the Golgi apparatus and its fusion with ER membranes. In order to delineate the effect of BFA on resident Golgi proteins, we investigated its effect on biosynthesis, maturation and intracellular transport of galactosyltransferase (gal-T), an established trans-Golgi enzyme. Using a protocol of metabolic labeling/immunoprecipitation followed by electrophoretic/fluorographic analysis, we show that in the presence of BFA, gal-T matures to a molecular form of 48.5 kD, a size intermediate between the 2 precursor forms of 44 and 47 and the mature form of 54 kD (Strous and Berger: J. Biol. Chem., 257:7623-28, 1982). Little mature form was detectable in the presence of BFA even after prolonged chase times of up to 28 hr. The intermediate form was sensitive to O-glycanase and endoglycosidase H, indicating early O-glycosylation without sialylation and lack of complex N-glycosylation, respectively. In order to define the compartment responsible for O-glycosylation in the presence of BFA, a temperature block of 25 degrees C was applied which inhibited recovery of Golgi elements from BFA-induced fusion with ER. At this temperature and in absence of BFA, biosynthesis of gal-T was not appreciably affected, while maturation was completely inhibited as indicated by the presence of unmodified precursor forms of gal-T. After 60 min preincubation with BFA, a time period sufficient to demonstrate complete fusion of Golgi with ER, subsequent biosynthesis of gal-T at 25 degrees C in absence of BFA led to the intermediate form, while precursor forms were not detectable. These data provide direct evidence for BFA-induced redistribution to the EF of Golgi enzymes involved in O-glycosylation and their early functional involvement in biosynthesis of newly synthesized gal-T.