Consciousness transitions during epilepsy seizures through the lens of integrated information theory

Consciousness is one of the most complex aspects of human experience. Studying the mechanisms involved in the transitions among different levels of consciousness remains as one of the greatest challenges in neuroscience. In this study we use a measure of integrated information (ΦAR) to evaluate dynamic changes during consciousness transitions. We applied the measure to intracranial electroencephalography (SEEG) recordings collected from 6 patients that suffer from refractory epilepsy, taking into account inter-ictal, pre-ictal and ictal periods. We analyzed the dynamical evolution of ΦAR in groups of electrode contacts outside the epileptogenic region and compared it with the Consciousness Seizure Scale (CCS). We show that changes on ΦAR are significantly correlated with changes in the reported states of consciousness.

Comparison of the Two Types of Stimulating Electrodes in the Study of Motor Nerve Conduction in Dogs

In this research two kinds of stimulation electrodes were compared in motor nerve conduction study: needle electrodes used in human medicine and electrodes made of injection needles connected to the stimulator via alligator-type electrodes. A study was conducted in 22 mixed-breed dogs. The resulting values of the potential amplitudes of the stimulus, the parameters of the complex muscle potentials, and the motor nerve conduction velocity were statistically compared. There was no statistical difference between the parameters obtained with the two types of stimulation electrodes. The results of our research constitute a basis for improving present-day procedures, improving aseptic procedures, reducing tissue trauma during research and lowering research costs due to the introduction of injection-needle electrodes and their benefits into the study of motor nerve conduction in animals.

Forward and inverse effects of the complete electrode model in neonatal EEG

The effect of the complete electrode model on electroencephalography forward and inverse computations is explored. A realistic neonatal head model, including a skull structure with fontanels and sutures, is used. The electrode and skull modeling differences are analyzed and compared with each other. The results suggest that the complete electrode model can be considered as an integral part of the outer head model. To achieve optimal source localization results, accurate electrode modeling might be necessary.

This paper investigates finite element method-based modeling in the context of neonatal electroencephalography (EEG). In particular, the focus lies on electrode boundary conditions. We compare the complete electrode model (CEM) with the point electrode model (PEM), which is the current standard in EEG. In the CEM, the voltage experienced by an electrode is modeled more realistically as the integral average of the potential distribution over its contact surface, whereas the PEM relies on a point value. Consequently, the CEM takes into account the subelectrode shunting currents, which are absent in the PEM. In this study, we aim to find out how the electrode voltage predicted by these two models differ, if standard size electrodes are attached to a head of a neonate. Additionally, we study voltages and voltage variation on electrode surfaces with two source locations: 1) next to the C6 electrode and 2) directly under the Fz electrode and the frontal fontanel. A realistic model of a neonatal head, including a skull with fontanels and sutures, is used. Based on the results, the forward simulation differences between CEM and PEM are in general small, but significant outliers can occur in the vicinity of the electrodes. The CEM can be considered as an integral part of the outer head model. The outcome of this study helps understanding volume conduction of neonatal EEG, since it enlightens the role of advanced skull and electrode modeling in forward and inverse computations.

NEW & NOTEWORTHY The effect of the complete electrode model on electroencephalography forward and inverse computations is explored. A realistic neonatal head model, including a skull structure with fontanels and sutures, is used. The electrode and skull modeling differences are analyzed and compared with each other. The results suggest that the complete electrode model can be considered as an integral part of the outer head model. To achieve optimal source localization results, accurate electrode modeling might be necessary.

The influence of sulcus width on simulated electric fields induced by transcranial magnetic stimulation

Volume conduction models can help in acquiring knowledge about the distribution of the electric field induced by transcranial magnetic stimulation. One aspect of a detailed model is an accurate description of the cortical surface geometry. Since its estimation is difficult, it is important to know how accurate the geometry has to be represented. Previous studies only looked at the differences caused by neglecting the complete boundary between cerebrospinal fluid (CSF) and grey matter (Thielscher et al 2011 NeuroImage 54 234-43, Bijsterbosch et al 2012 Med. Biol. Eng. Comput. 50 671-81), or by resizing the whole brain (Wagner et al 2008 Exp. Brain Res. 186 539-50). However, due to the high conductive properties of the CSF, it can be expected that alterations in sulcus width can already have a significant effect on the distribution of the electric field. To answer this question, the sulcus width of a highly realistic head model, based on T1-, T2- and diffusion-weighted magnetic resonance images, was altered systematically. This study shows that alterations in the sulcus width do not cause large differences in the majority of the electric field values. However, considerable overestimation of sulcus width produces an overestimation of the calculated field strength, also at locations distant from the target location.

Impact of pesticide contamination on aquatic microorganism populations in the littoral zone

The effect of pesticide contamination of the littoral zone on the population of bacteria and fungi was analyzed using the example of a eutrophic water reservoir exposed for >30 years to the influence of expired crop-protection chemicals, mainly DDT. For three consecutive years, quantity analyses of bacteria and fungi were conducted and the composition of the microorganism population analyzed against seasonal dynamics. Mold and yeast-like fungi were also isolated and identified. Within the Bacteria domain, in addition to the large groups of microorganisms (Alphaprotobacteria, Betaprobacteria, and Gammaproteobacteria, Actinobacteria, and Cytophaga-Flavobacterium), the analysis also involved the presence of bacteria predisposed to degraded pesticides in natural environments: Pseudomonas spp. and Alcaligenes spp. The quantity dynamics of aquatic microorganisms indicated that bacteria and fungi under the influence of long-term exposure to DDT can adapt to the presence of this pesticide in water. No modifying effect of DDT was observed on the quantity of microorganisms or the pattern of seasonal relationships in the eutrophic lake. Changes were shown in the percentage share of large groups of bacteria in the community of microorganisms as was an effect of contamination on the species diversity of fungi. The data show the effectiveness of aquatic microorganism-community analyses as a tool for indicating changes in the water environment caused by pesticide contamination.

The clinical significance of class III (suspicious) urine cytology

BACKGROUND

Urine cytology, combined with cystoscopy, is the mainstay of the diagnosis and surveillance of urothelial carcinoma (UC). While classes I and II urine cytology are considered benign and classes IV and V are considered malignant the clinical significance of class III urine cytology is unclear. We evaluated the positive predictive value of class III urine cytology for concurrent and subsequent UC.

METHODS

The records of all class III urine cytology cases during a 3-year period were retrospectively reviewed for the presence of concurrent and subsequent UC, determined by cystoscopy and histological confirmation.

RESULTS

Of 111 cases, 54 (48.7%) were associated with concurrent UC and 14 (12.6%) with subsequent UC after an initial evaluation negative for malignancy, with a mean time to diagnosis of 10.8 months. Of 27 cases of class III urine cytology with no prior history of UC, 13 (48.1%) had concomitant UC and none had subsequent UC. Of 84 cases of class III urine cytology with a prior history of UC, 41 (48.8%) had a concomitant diagnosis of UC and 14 (16.7%) developed UC during their follow-up, leading to a total of 55 (65.5%) cases of UC.

CONCLUSIONS

Patients with class III urine cytology and a prior history of UC should undergo a full initial evaluation of their urinary tract, and should be followed vigorously if this evaluation is negative for malignancy. Patients without a prior diagnosis of UC and class III urine cytology should also undergo a full initial evaluation, while further larger studies are needed to elucidate the need for further follow-up in such patients.

Accuracy and run-time comparison for different potential approaches and iterative solvers in finite element method based EEG source analysis

Accuracy and run-time play an important role in medical diagnostics and research as well as in the field of neuroscience. In Electroencephalography (EEG) source reconstruction, a current distribution in the human brain is reconstructed noninvasively from measured potentials at the head surface (the EEG inverse problem). Numerical modeling techniques are used to simulate head surface potentials for dipolar current sources in the human cortex, the so-called EEG forward problem.In this paper, the efficiency of algebraic multigrid (AMG), incomplete Cholesky (IC) and Jacobi preconditioners for the conjugate gradient (CG) method are compared for iteratively solving the finite element (FE) method based EEG forward problem. The interplay of the three solvers with a full subtraction approach and two direct potential approaches, the Venant and the partial integration method for the treatment of the dipole singularity is examined. The examination is performed in a four-compartment sphere model with anisotropic skull layer, where quasi-analytical solutions allow for an exact quantification of computational speed versus numerical error. Specifically-tuned constrained Delaunay tetrahedralization (CDT) FE meshes lead to high accuracies for both the full subtraction and the direct potential approaches. Best accuracies are achieved by the full subtraction approach if the homogeneity condition is fulfilled. It is shown that the AMG-CG achieves an order of magnitude higher computational speed than the CG with the standard preconditioners with an increasing gain factor when decreasing mesh size. Our results should broaden the application of accurate and fast high-resolution FE volume conductor modeling in source analysis routine.

Subject-specific, multiscale simulation of electrophysiology: a software pipeline for image-based models and application examples

Many simulation studies in biomedicine are based on a similar sequence of processing steps, starting from images and running through geometric model generation, assignment of tissue properties, numerical simulation and visualization of the results--a process known as image-based geometric modelling and simulation. We present an overview of software systems for implementing such a sequence both within highly integrated problem-solving environments and in the form of loosely integrated pipelines. Loose integration in this case indicates that individual programs function largely independently but communicate through files of a common format and support simple scripting, so as to automate multiple executions wherever possible. We then describe three specific applications of such pipelines to translational biomedical research in electrophysiology.

Short-term results of Ahmed glaucoma valve implantation in the surgical treatment of angle-recession glaucoma in dog

Angle-recession glaucoma, being a consequence of blunt injury of an eyeball, is likely to develop in both a short or very distant period. The likelihood of the incidence of that condition in the clinical form is determined by the extent of injuries of ciliary cleft structures, especially of a trabecular meshwork. The manuscript reports a case of an early glaucoma secondary to a blunt injury of an eyeball with symptoms of angle recession to 300 degrees of periphery and intraocular pressure (IOP) at a level of 62 mmHg. The basic diagnostic examination that enables the evaluation of an angle, iris root and an opening to the ciliary cleft is gonioscopy. In case of a lack of response to the pharmacological reduction of IOP, a method of choice still remains a surgical procedure. In the reported case, a drainage procedure was applied in the form of implantation of the Ahmed valve prosthesis. Control tonometric examinations of the operated eye, performed over a 20-week period of postoperative management, demonstrated IOP at a level of 19 mmHg.

Cyclodialysis in the treatment of nonhealing secondary glaucoma

In cases of glaucoma with elevated intra ocular pressure, the first objective of treatment is its reduction and normalization. In cases when excessive pressure has resulted in a loss of vision, the aim of treatment is to attenuate the pain and to improve the comfort of the patient. This paper presents a case of glaucoma secondary to anterior uveitis, resistant to pharmacological treatment. A gonioscopic examination in both eyes revealed a narrowed filtration angle. An ophthalmoscopic examination of the fundus showed partial retinal detachment. The cyclodialysis procedure was performed in both eyes. In the post-surgery period, intraocular pressure (IOP) in both eyes showed a downward tendency. The treatment of glaucoma secondary to anterior uveitis, particularly in its advanced state, often requires the combination of pharmacological treatment with a surgical procedure. Positive results in maintaining the patency of the fistula were observed after the application of a steroid therapy and a regular massage of filtration bleb, which significantly contributed to maintaining IOP at a desired level.

Peritoneal dialysis in dogs and cats

The peritoneal dialysis was carried out in dogs for the fist time in 1946. Since then, this method of therapy has been applied more and more frequently in veterinary medicine. The dialysis therapy is mainly recommended in the acute renal failure. Accordingly to the time period over which dialysis is performed and the flow pattern of the dialysate, different types of the peritoneal dialysis are distinguished. In carnivores, intermittent peritoneal dialysis is the most commonly applied method of dialysotherapy. However, despite a considerable effectiveness of this method, complications including uncontrolled transportation of elements and proteins or problems with catheter occur quite often. This article describes indications and contraindications which enable to qualify animal patients for dialysotherapy, and detailed principles of peritoneal dialysis procedure.

The effect of propofol on acid-base balance and ionic composition of venous and arterial blood in goats

The aim of the present study was to determine the effect of propofol on acid-base balance and ionic composition of arterial and venous blood in clinically healthy goats. The experiment was performed on ten adult goats. Propofol was administered intravenously at bolus dose of 6 mg/kg bw. The heart and breath rate, acid-base balance (pH, pCO2, pO2, HCO3-, BE, O2SAT, ctCO2) and ionic composition (Na+, K+, Cl-) of arterial and venous blood were measured before injection and 3, 6 and 15 min. after. The propofol infusion induced increase of heart rate, decrease of breath rate and compensated respiratory acidosis in venous and arterial blood. It was found that changes of acid-base balance parameters in arterial blood arose faster than in venous blood. The levels of sodium and chloride ions in both types of blood were similar, whereas the level of potassium ions was higher in venous blood during entire experiment.

Intravenous administration of an AAV-2 vector for the expression of factor IX in mice and a dog model of hemophilia B

Previous experiments have demonstrated the stable expression of factor IX (FIX) protein in mice and canine models of hemophilia B following portal vein gene transfer with a recombinant adeno-associated virus (rAAV) vector encoding FIX. Here, we present the results of studies that further optimized the rAAV vector transgene cassette used to express FIX and explored the use of the less-invasive intravenous (i.v.) route of vector administration for the treatment of hemophilia B. First, a liver-specific promoter was evaluated in conjunction with cis-acting regulatory elements in mice. Constructs that included both the beta-globin intron and the woodchuck hepatitis virus post-transcriptional regulatory element resulted in the highest level of FIX expression in vivo. Using this optimized vector, we demonstrate that i.v. injection was feasible for hepatic gene transfer in mice, achieving 70-80% of portal vein expression levels of FIX. In further studies using the Chapel Hill strain of hemophilia B dogs, we demonstrate for the first time FIX expression and partial correction of the bleeding disorder following i.v. administration of an AAV vector.

The relationship between competence and performance: implications for assessing practice performance

OBJECTIVE

This paper aims to describe current views of the relationship between competence and performance and to delineate some of the implications of the distinctions between the two areas for the purpose of assessing doctors in practice.

METHODS

During a 2-day closed session, the authors, using their wide experiences in this domain, defined the problem and the context, discussed the content and set up a new model. This was developed further by e-mail correspondence over a 6-month period.

RESULTS

Competency-based assessments were defined as measures of what doctors do in testing situations, while performance-based assessments were defined as measures of what doctors do in practice. The distinction between competency-based and performance-based methods leads to a three-stage model for assessing doctors in practice. The first component of the model proposed is a screening test that would identify doctors at risk. Practitioners who 'pass' the screen would move on to a continuous quality improvement process aimed at raising the general level of performance. Practitioners deemed to be at risk would undergo a more detailed assessment process focused on rigorous testing, with poor performers targeted for remediation or removal from practice.

CONCLUSION

We propose a new model, designated the Cambridge Model, which extends and refines Miller's pyramid. It inverts his pyramid, focuses exclusively on the top two tiers, and identifies performance as a product of competence, the influences of the individual (e.g. health, relationships), and the influences of the system (e.g. facilities, practice time). The model provides a basis for understanding and designing assessments of practice performance.

Changes in the distribution of anionic constituents in secretory granules of mouse pancreatic acinar cells after pilocarpine-induced degranulation

We used cationized colloidal gold (CCG) to investigate the distribution of anionic sites in different secretory granules of mouse pancreatic acinar cell regranulation. Localization of anionic sites with CCG was carried out on ultrathin sections of a mouse pancreas, fixed in Karnovsky's fixative and OsO4 and embedded in Araldite. After pilocarpine-stimulated degranulation, there was a marked diminution in the anionic charge density of immature and mature granules of the 4-hr group (approximately 43.0 gold particles/microm2) compared to the 8-hr mature granules group (approximately 64.6 gold particles/microm2). Scattergram analysis to investigate the correlation between section profile size and cationized gold labeling density revealed a reverse correlation, the small granule profiles demonstrated a higher density compared to the larger profiles of the same group. On the basis of these observations, it appears that a post-translational processing of secretory content influences the granule anionic charge and thus may affect the intragranular buffer capacity.

The scid recombination-inducible cell line: a model to study DNA-PK-independent V(D)J recombination

To investigate the molecular mechanisms of the variable (diversity) joining (V(D)J) recombination process at an endogenous gene locus, recombination-inducible cell lines were made from both bcl-2-bearing severe combined immune deficiency (scid) homozygous and scid heterozyous (s/ + ) mice by transforming pre-B cells with the temperature-sensitive Abelson murine leukemia virus (ts-Ab-MLV). These transformants can be induced to undergo immunoglobulin light-chain gene rearrangements by incubating them at the non-permissive temperature. In the case of transformed scid cells, a significant amount of hairpin coding ends are accumulated during recombination induction, but few coding joints are generated. After being shifted to the permissive temperature. however, these cells are capable of opening hairpin ends and forming coding joints. Thus, ts-Ab-MLV transformed scid cells can be readily manipulated for both recombination cleavage and end resolution. However, unlike the rapid coding joint formation in s/ + cells that have the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), the process for resolving coding ends in scid cells is slow and error prone, and also appears to be correlated with a reduction in the RAG1/2 expression. Apparently, this process is mediated by a DNA-PK-independent pathway. The fact that the activity of this pathway can be manipulated in vitro makes it possible to delineate the mechanisms in end opening, processing and joining. Therefore, these ts-Ab-MLV transformed scid cell lines offer a model to study the molecular nature as well as the regulation of the DNA-PK-independent pathway in coding end resolution.

Activation of V(D)J recombination induces the formation of interlocus joints and hybrid joints in scid pre-B-cell lines

V(D)J recombination is the mechanism by which antigen receptor genes are assembled. The site-specific cleavage mediated by RAG1 and RAG2 proteins generates two types of double-strand DNA breaks: blunt signal ends and covalently sealed hairpin coding ends. Although these DNA breaks are mainly resolved into coding joints and signal joints, they can participate in a nonstandard joining process, forming hybrid and open/shut joints that link coding ends to signal ends. In addition, the broken DNA molecules excised from different receptor gene loci could potentially be joined to generate interlocus joints. The interlocus recombination process may contribute to the translocation between antigen receptor genes and oncogenes, leading to malignant transformation of lymphocytes. To investigate the underlying mechanisms of these nonstandard recombination events, we took advantage of recombination-inducible cell lines derived from scid homozygous (s/s) and scid heterozygous (s/+) mice by transforming B-cell precursors with a temperature-sensitive Abelson murine leukemia virus mutant (ts-Ab-MLV). We can manipulate the level of recombination cleavage and end resolution by altering the cell culture temperature. By analyzing various recombination products in scid and s/+ ts-Ab-MLV transformants, we report in this study that scid cells make higher levels of interlocus and hybrid joints than their normal counterparts. These joints arise concurrently with the formation of intralocus joints, as well as with the appearance of opened coding ends. The junctions of these joining products exhibit excessive nucleotide deletions, a characteristic of scid coding joints. These data suggest that an inability of scid cells to promptly resolve their recombination ends exposes the ends to a random joining process, which can conceivably lead to chromosomal translocations.

The effects of polar and/or ionizable residues in the core and flanking regions of hydrophobic helices on transmembrane conformation and oligomerization

To explore the influence of amino acid composition on the behavior of membrane-inserted alpha-helices, we examined the behavior of Lys-flanked polyleucyl (pLeu) helices containing a single polar/ionizable residue within their hydrophobic core. To evaluate the location of the helices within the membrane by fluorescence, each contained a Trp residue at the center of the sequence. When incorporated into dioleoylphosphatidylcholine (DOPC) model membrane vesicles, pLeu helices with or without a single Ser, Asn, Lys, or Asp residue in the hydrophobic core maintained a transmembrane state (named the N state) at neutral and acidic pH. In this state, the central Trp exhibited highly blue-shifted fluorescence, and fluorescence quenching by nitroxide-labeled lipids showed it located at the bilayer center. A state in which Trp fluorescence red-shifted by several nanometers (named the B state) was observed above pH 10-11. B state formation appears to result from deprotonation of the flanking Lys residues. Despite the red shift in Trp emission, fluorescence quenching showed that in the B state the Trp at most is only slightly shallower than in the N state, suggesting the B state also is a transmembrane or near-transmembrane structure. The B state is characterized by increased helix oligomerization, as shown by the dependence of Trp lambda(max) on the concentration of the peptide within the bilayer at high pH. The pLeu peptide with a Asp residue in the core underwent a pH-dependent transition at a lower pH than the other peptides (pH 8-9). At high pH, it exhibited both a more highly red-shifted fluorescence and shallower Trp location than the other peptides. This state (named the S state) did not exhibit a concentration-dependent Trp lambda(max). We attribute S state behavior to the formation of a charged Asp residue at high pH, and a consequent movement of the Asp toward the membrane surface, resulting in the formation of a nontransmembrane state. We conclude that a polar or ionizable residue can readily be tolerated in a single transmembrane helix, but that the charges on ionizable residues in the core and regions flanking the helix significantly modulate the stability of transmembrane insertion and/or helix-helix association.

Brain tumor invasion rate measured in vitro does not correlate with Ki-67 expression

The need for more accurate prediction of the biological behavior of brain tumors has lead to the use of immunohistochemical methods for assessment of proliferating cell nuclear antigens such as Ki-67. There is a variable association of glioma Ki-67 labeling index with patient survival. Brain invasion by individual tumor cells also defines biological aggressiveness, and can be assessed in vitro. Further, proliferation and migration seem to be mutually exclusive behaviors for a given cell at a point in time. We studied the relationship between Ki-67 labeling index and invasion rate in a group of 10 gliomas, and 2 meningiomas. Human tumor spheroids obtained from operative specimen were co-cultured with fetal rat brain aggregates, and invasion rate was measured by confocal microscopic observation. There was no correlation between two measures of invasion and Ki-67 labeling. This finding supports the dichotomous nature of glioma proliferation and invasion, and may in part explain the limited usefulness of proliferation marker labeling.

The value of sonohysterography combined with cytological analysis of the fluid retrieved from the endometrial cavity in predicting histological diagnosis

OBJECTIVE

The purpose of the study was to assess the efficacy of sonohysterography combined with cytological analysis of the fluid retrieved from the endometrial cavity in predicting histological diagnosis.

STUDY DESIGN

A prospective study was conducted comparing sonohysterography combined with endometrial washings for cytology with histological evaluation after surgical procedures. Of 152 patients referred for sonohysterography, 87 were premenopausal and 65 were postmenopausal. Some of the injected fluid was aspirated for cytological analysis. Sixty-one patients (40%) underwent surgical hysteroscopy and eight (5%) had dilatation and curettage as a result of the sonohysterographic findings. Histological diagnoses were compared with the sonohysterographic and cytological findings.

RESULTS

In 99 (65%) patients, sonohysterography demonstrated endometrial polypoid lesions. Only 54 endometrial cavitary lesions were confirmed pathologically. Epithelial cells with atypia were more often found in patients without (five of 53) than in those with (two of 99) an endometrial polyp (p < 0.05). Only one out of nine cases of histological diagnosis of hyperplasia was predicted cytologically.

CONCLUSIONS

The addition of cytological analysis of the fluid retrieved from the endometrial cavity during sonohysterography did not contribute to the prediction of benign histological diagnosis of endometrial hyperplasia.

Control of the transmembrane orientation and interhelical interactions within membranes by hydrophobic helix length

We examined the effect of the length of the hydrophobic core of Lys-flanked poly(Leu) peptides on their behavior when inserted into model membranes. Peptide structure and membrane location were assessed by the fluorescence emission lambdamax of a Trp residue in the center of the peptide sequence, the quenching of Trp fluorescence by nitroxide-labeled lipids (parallax analysis), and circular dichroism. Peptides in which the hydrophobic core varied in length from 11 to 23 residues were found to be largely alpha-helical when inserted into the bilayer. In dioleoylphosphatidylcholine (diC18:1PC) bilayers, a peptide with a 19-residue hydrophobic core exhibited highly blue-shifted fluorescence, an indication of Trp location in a nonpolar environment, and quenching localized the Trp to the bilayer center, an indication of transmembrane structure. A peptide with an 11-residue hydrophobic core exhibited emission that was red-shifted, suggesting a more polar Trp environment, and quenching showed the Trp was significantly displaced from the bilayer center, indicating that this peptide formed a nontransmembranous structure. A peptide with a 23-residue hydrophobic core gave somewhat red-shifted fluorescence, but quenching demonstrated the Trp was still close to the bilayer center, consistent with a transmembrane structure. Analogous behavior was observed when the behavior of individual peptides was examined in model membranes with various bilayer widths. Other experiments demonstrated that in diC18:1PC bilayers the dilution of the membrane concentration of the peptide with a 23-residue hydrophobic core resulted in a blue shift of fluorescence, suggesting the red-shifted fluorescence at higher peptide concentrations was due to helix oligomerization. The intermolecular self-quenching of rhodamine observed when the peptide was rhodamine-labeled, and the concentration dependence of self-quenching, supported this conclusion. These studies indicate that the mismatch between helix length and bilayer width can control membrane location, orientation, and helix-helix interactions, and thus may mismatch control both membrane protein folding and the interactions between membrane proteins.

Morphometric studies of secretory granule formation in mouse pancreatic acinar cells. Dissecting the early structural changes following pilocarpine injection

Secretory granule formation in pancreatic acinar cells is known to involve massive membrane flow. In previous studies we have undertaken morphometry of the regranulation mechanism in these cells and in mast cells as a model for cellular membrane movement. In our current work, electron micrographs of pancreatic acinar cells from ICR mice were taken at several time points after extensive degranulation induced by pilocarpine injection in order to investigate the volume changes of rough endoplasmic reticulum (RER), nucleus, mitochondria and autophagosomes. At 2-4 h after stimulation, when the pancreatic cells demonstrated a complete loss of granules, this was accompanied by an increased proportion of autophagosomal activity. This change primarily reflected a greatly increased proportion of profiles retaining autophagic vacuoles containing recognisable cytoplasmic structures such as mitochondria, granule profiles and fragments of RER. The mitochondrial structures reached a significant maximal size 4 h following injection (before degranulation 0.178 +/- 0.028 microm3; at 4 h peak value, 0.535 +/- 0.109 microm3). Nucleus size showed an early volume increase approaching a maximum value 2 h following degranulation. The regranulation span was thus divided into 3 stages. The first was the membrane remodelling stage (0-2 h). During this period the volume of the RER and secretory granules was greatly decreased. At the intermediate stage (2-4 h) a significant increase of the synthesis zone was observed within the nucleus. The volume of the mitochondria was increasing. At the last step, the major finding was a significant granule accumulation in parallel with an active Golgi zone.

A 30s PAS stain for frozen section analysis of surgical margins of vulvectomy in Paget's disease

Application of a modified periodic-acid Schiff's procedure (PAS) technique in frozen section analysis of surgical margins of vulvectomy specimen in Paget's disease is described. The reaction obtained using a microwave procedure takes only 30 seconds. This method was found to be useful in identifying Paget cells on the margins thought to be free of disease by conventional histological evaluation.

Transmembrane orientation of hydrophobic alpha-helices is regulated both by the relationship of helix length to bilayer thickness and by the cholesterol concentration

A fluorescence-based approach to evaluate the regulation of transmembrane orientation of alpha-helices has been developed to examine the behavior of a membrane-inserted alpha-helical peptide with a 19 residue hydrophobic sequence. The emission lambdamax of a Trp residue in the helix was used to determine its location in the bilayer. To calibrate this method, Trp lambdamax and depth (determined by parallax analysis of fluorescence quenching) were measured for transmembrane peptides with Trp at different positions. Transmembrane orientation of the alpha-helix was found to be destabilized by differences between the width of the bilayer and the length of the hydrophobic sequence (i.e., hydrophobic mismatch). When bilayer width exceeded the length of the hydrophobic segment, mismatch induced formation of a nontransmembraneous orientation close to the polar/hydrocarbon interface. By manipulation of bilayer width in situ, it was found that the transmembrane and nontransmembrane orientations could interconvert. Cholesterol altered the transmembrane/nontransmembrane equilibrium to a degree consistent with its tendency to increase bilayer thickness. Evaluation of the energetics of transmembrane vs nontransmembrane insertion showed increased mismatch of a helix with bilayer width by the equivalent of just one hydrophobic residue can destabilize transmembrane orientation by roughly 0.5 kcal/mol. Inclusion of 30 mol % cholesterol in a bilayer can alter transmembrane insertion stability by 3-5 kcal/mol. Thus, physiologically relevant variations in both the hydrophobic helix length/membrane thickness ratio and the cholesterol levels influence transmembrane insertion significantly.

Mucosal addressin cell adhesion molecule-1: a structural and functional analysis demarcates the integrin binding motif

The leukocyte integrin receptor, alpha 4 beta 7, and the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are postulated to be important in regulating lymphocyte trafficking to normal intestine. Here we provide the first description of MAdCAM-1 expression in inflamed intestine. Using mouse models of experimentally induced colitis, we show a concordant increase in MAdCAM-1 expression associated with increased cellular infiltrates in areas of intestinal inflammation. To understand more of the molecular nature of the interactions between MAdCAM-1 and its leukocyte ligand, the alpha 4 beta 7 integrin receptor, we have analyzed the structural and functional properties of chimeric recombinant MAdCAM-1 proteins in vitro. Using site-directed mutagenesis and molecular modeling, we demarcate the alpha 4 beta 7 binding motif as three linear residues within the C-D loop in the first domain of MAdCAM-1. Mutation of residue L40, D41, or T42 in the first domain completely abrogates alpha 4 beta 7+ cell binding and cellular activation. Mutagenesis of other residues in the first domain do not impact these functions. We have modeled peptides based on the predicted structure of the alpha 4 beta 7 integrin binding motif on MAdCAM-1 and are able to show specific and selective blocking of cell binding. These observations suggest that the amino acid residues LDT on MAdCAM-1 play a role in the interaction with alpha 4 beta 7 in cell adherence and cell activation.

Mucosal addressin cell adhesion molecule-1: a structural and functional analysis demarcates the integrin binding motif

The leukocyte integrin receptor, alpha 4 beta 7, and the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are postulated to be important in regulating lymphocyte trafficking to normal intestine. Here we provide the first description of MAdCAM-1 expression in inflamed intestine. Using mouse models of experimentally induced colitis, we show a concordant increase in MAdCAM-1 expression associated with increased cellular infiltrates in areas of intestinal inflammation. To understand more of the molecular nature of the interactions between MAdCAM-1 and its leukocyte ligand, the alpha 4 beta 7 integrin receptor, we have analyzed the structural and functional properties of chimeric recombinant MAdCAM-1 proteins in vitro. Using site-directed mutagenesis and molecular modeling, we demarcate the alpha 4 beta 7 binding motif as three linear residues within the C-D loop in the first domain of MAdCAM-1. Mutation of residue L40, D41, or T42 in the first domain completely abrogates alpha 4 beta 7+ cell binding and cellular activation. Mutagenesis of other residues in the first domain do not impact these functions. We have modeled peptides based on the predicted structure of the alpha 4 beta 7 integrin binding motif on MAdCAM-1 and are able to show specific and selective blocking of cell binding. These observations suggest that the amino acid residues LDT on MAdCAM-1 play a role in the interaction with alpha 4 beta 7 in cell adherence and cell activation.

The efficacy of brief group counseling in HIV risk reduction among homosexual Asian and Pacific Islander men

OBJECTIVES

The incidence of AIDS is increasing at a higher rate among homosexual Asian and Pacific Islanders (API) than white homosexual men in the United States. The number of homosexual API men engaging in unsafe sex is increasing at an alarming rate. HIV risk reduction is urgently needed in this population.

SUBJECTS AND METHODS

We developed and evaluated culturally appropriate brief group counseling with 329 self-identified homosexual API recruited in San Francisco between 1992 and 1994. Participants were randomized into a single, 3-h skills training group or a wait-list control group. The intervention consisted of four components: (1) development of positive self-identity and social support, (2) safer sex education, (3) eroticizing safer sex, and (4) negotiating safer sex. Data were collected at baseline and 3 months after the intervention.

RESULTS

Significant reductions in number of sexual partners were observed among all treatment subjects, regardless of ethnicity (P = 0.003). Treatment decreased the number of partners reported at 3-month follow-up by 46% [95% confidence interval (CI), 28-77]. Chinese and Filipino men further benefited from the intervention: treatment subjects from these two ethnic groups reduced unprotected anal intercourse at follow-up by more than half when compared to their counterparts (odds ratio = 0.41; 95% CI, 0.19-0.89; P = 0.024).

CONCLUSIONS

We demonstrated the efficacy of brief group counseling in reducing HIV risk among homosexual API. Cities with significant API populations should adopt culturally tailored skills training as part of HIV prevention strategies for this group of homosexual men.

Prostaglandin E2 production by chronic graft-versus-host disease dermal fibroblasts

Chronic graft versus host disease (cGVHD) across minor histocompatibility barriers is associated with the development of cutaneous fibrosis, disappearance of mast cells and immunosuppression. The idea, which has been the basis of our previous and present studies, is that fibroblasts are not only a target for modulation in cGVHD, but also have effector roles in this condition. In the present study we investigated the production of prostaglandin E2 (PGE2) and of collagen by cultured dermal fibroblasts obtained from cGVHD and control mice. Early in the development of the disease (Day 8) cGVHD fibroblasts generated constitutively more PGE2 (3-fold) than did control fibroblasts. Thereafter, PGE2 production declined to near normal levels by Day 20 post cGVHD induction. On the other hand, at this time point cGVHD fibroblasts displayed an enhanced synthesis of collagen as compared to the control fibroblasts and to earlier time points. Therefore, PGE2 synthesis appears to inversely correlate with collagen synthesis by cGVHD fibroblasts. We propose that fibroblasts may contribute to the development of immunosuppression, which characterizes the early phase of cGVHD.

Ovarian endometrioid carcinoma and endometriosis developing in a postmenopausal breast cancer patient during tamoxifen therapy: a case report and review of the literature

We present the first case of ovarian endometrioid carcinoma and endometriosis in a postmenopausal patient who was treated with tamoxifen for breast cancer. The association with prolonged unopposed estrogen-like stimulation with tamoxifen as a possible factor in the development of ovarian endometrioid carcinoma is discussed.

Cytoplasmic granule formation in mouse pancreatic acinar cells. Evidence for formation of immature granules (condensing vacuoles) by aggregation and fusion of progranules of unit size, and for reductions in membrane surface area and immature granule volume during granule maturation

We used a computer-assisted morphometry approach to analyze quantitatively the process of cytoplasmic granule formation in mouse pancreatic acinar cells stimulated with pilocarpine to induce secretion. Our findings suggest that each condensing vacuole/immature granule of pancreatic acinar cells is formed by the progressive aggregation of 106 to 128 "unit progranules" of narrowly fixed volume, define a range of 7.7 to 9.2 for the factor of volume condensation between the largest immature granules and the mature unit granule, and predict that the formation of a single mature unit granule by the aggregation and fusion of unit progranules involves a net reduction of at least 95% in the amount of membrane surface area associated with these structures.

Triple approach in the diagnosis of dominant breast masses: combined physical examination, mammography, and fine-needle aspiration

In an attempt to reduce the number of breast biopsies done for benign breast disease in patients with breast lumps, we evaluated prospectively the sensitivity and specificity of the combination of three diagnostic modalities: clinical examination, mammography, and fine-needle aspiration cytologic examination (FNA). A total of 234 patients with a breast mass had a physical examination, a mammogram, and FNA, and were listed as malignant/suspicious or benign. All patients underwent a subsequent biopsy: 110 were found to have breast cancer, and 124 had a benign lesion. The sensitivity and specificity of the individual tests were as follows: 89% and 73%, respectively, for mammographic examination; 93% and 97% for FNA cytologic examination; and 89% and 60% for physical examination. For the combined triad of tests, the sensitivity was 100% and specificity 57%. All patients who had breast cancer had positive findings for malignancy in one or more of the diagnostic tests, i.e., 100% sensitively. All patients who had negative findings for malignancy in all three diagnostic tests had benign lesions, i.e., a negative predictive value of 100%. We conclude that breast masses can be diagnosed with a high degree of accuracy by combined physical, mammographic, and fine-needle aspiration cytologic examination. Patients in whom physical examination, mammography, and FNA were negative for malignancy can be safely observed, obviating the need for an open biopsy.

Measurement of kinetic parameters for urea in end-stage renal disease patients using a two-compartment model

Urea kinetic modeling depends critically on the parameters of the model used. When urea is removed during hemodialysis, the kinetic model is quite complex. This experiment describes for the first time the use of injected stable isotope-labeled urea to define kinetics in ESRD patients and compares the magnitude of the two urea compartments in these patients with those of control subjects. Such an experimental approach provides the kinetic data in the most direct manner. A gas chromatograph/mass spectrometer-based assay provided quantitation to as little as 0.2 mol% excess urea. The rapidly equilibrating fraction of the two urea compartments is quantified as 41.2% in ESRD patients and 33.4% in controls (P = 0.24). The rest is in a more slowly equilibrating pool. The urea clearances between these two compartments were near 1 L/min for both sets of subjects. The elimination of urea was due to the metabolic removal of the 15N label in both groups of subjects as well as renal elimination in the controls. The nearly threefold larger clearance (Cl) of labeled urea removal in controls (Cl = 74.6 mL/min) than in ESRD patients (Cl = 25.4 mL/min; P = 0.015) shows the extent to which renal clearance is more important than metabolism. These direct analyses of the fractional volumes and intercompartmental clearances for urea agree closely with previous measurements during high-efficiency hemodialysis and indicate that ESRD patients do not differ significantly from control subjects in these parameters.

Preoperative chemotherapy in the management of intracaval extension of Wilms' tumor

Extension of Wilms' tumor into the renal vein and vena cava complicates the operative treatment of a small but significant number of patients. Two children presented with Wilms' tumor and intracaval tumor extension. After biopsy, both children were given chemotherapy. In one case the tumor completely disappeared from the vena cava, and in the other the tumor regressed substantially, and proximal control became possible at the level of the infrahepatic vena cava. Both children then had an uneventful nephrectomy that was greatly simplified. We conclude that preoperative chemotherapy can induce resolution of intravascular tumor, and may be a useful option in cases of extension of Wilms' tumor into the vena cava.

Normal pregnancy complicated by vaginal ectopic trophoblastic implantation; a case report

We describe a rare case of ectopic placental tissue, presenting as a vaginal tumor during normal intra-uterine pregnancy. Its clinicopathological features, and its possible relation to placental site trophoblastic tumors are discussed. To the best of our knowledge, this is the first case to be reported in the English literature of such a lesion occurring at this site.

A blue naevus of the prostate: a light microscopic study including an investigation of S-100 protein positive cells in the normal and in the diseased gland

A blue naevus of the prostate in an 80-year-old patient is presented, including electronmicroscopical examination and the demonstration of S-100 protein positivity. Cells expressing S-100 protein were sought in prostates of infants, young adults and elderly patients with hyperplasia and carcinoma. Positive staining was found in stromal cells, but the number diminished with age and disease. These findings could explain the rarity of blue naevus and the virtual absence of primary malignant melanoma in the prostate.