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PubMed1987

The study of mammalian organogenesis by mosaic pattern analysis.

Chimeras are animals derived from more than one zygote and composed of two cell lineages which are distinguishable in some way at the cellular level. Spontaneous mosaic animals are also composed of distinguishable cell lineages but are monozygotic. The tissues of both mono- and multizygotic animals of this type are mosaic arrays in which aggregates of like cells form patches, the size and distribution of which can be useful in the analysis of diverse problems in developmental biology. Both biochemical and in situ methods have been applied to the elucidation of mosaic pattern. Both forms of mosaicism have proven useful in establishing theoretic constructs of the formation and maintenance of mammalian organs. A number of these constructs are discussed: cell fusion as related to myotube formation; mechanisms of coat pigmentation and the cellular origin of melanocytes; and pattern analyses of the retinal pigmented epithelium, the intestine, liver, adrenal cortex and thymus. Pathologic alterations in such animals have also been studied utilizing mosaic pattern analysis. In particular, neoplastic tumors and their associated preneoplastic lesions have been shown to be clonal.

Animals↗
PubMed1995

Altered (copy-up) forms of initiator protein pi suppress the point mutations inactivating the gamma origin of plasmid R6K.

The R6K gamma origin core contains the P2 promoter, whose -10 and -35 hexamers overlap two of the seven binding sites for the R6K-encoded pi protein. Two mutations, P2-201 and P2-203, which lie within the -35 region of P2, are shown to confer a promoter-down phenotype. We demonstrate here that these mutations prevent replication of a gamma origin core plasmid. To determine whether or not the reduced promoter activity caused by these mutations is responsible for their effect on replication, we generated two new mutations (P2-245-6-7 and P2-246) in the -10 hexamer of the P2 promoter. Although these new mutations inhibit P2 activity as much as the P2-201 and P2-203 mutations, they do not prevent replication of the gamma origin core. Therefore, activity of the P2 promoter does not appear to be required for replication. We also show that the inability of the gamma origin to function in the presence of the P2-201 and P2-203 mutations is reversed by the hyperactive variants of pi protein called copy-up pi. This suppression occurs despite the fact that in vivo dimethyl sulfate methylation protection patterns of the gamma origin iterons are identical in cells producing wild-type pi and those producing copy-up pi variants. We discuss how the P2-201 and P2-203 mutations could inhibit replication of the gamma origin core and what mechanisms might allow the copy-up pi mutants to suppress this deficiency.

Bacterial Proteins↗
PubMed1999

Separate memory-related processing for auditory frequency and patterns.

Detecting deviant, and potentially meaningful, auditory events depends on transient representations of preceding stimuli. Here, we examined whether the neural circuitry underlying deviance detection system varied as a function of deviance type. In different blocks of trials, participants were presented with a sequence that included standard and deviant tones differing in frequency or a sequence of tones that alternated regularly in frequency with occasional deviant repetitions. Both frequency- and pattern-deviant stimuli elicited a mismatch negativity (MMN) peaking between 120 and 175 ms poststimulus. The MMN amplitude distribution was more frontal for frequency-deviant than for pattern-deviant stimuli. There are two possible explanations for these results. Both frequency- and pattern-deviation MMNs might arise in the same set of generators whose relative strength of activation varies. Alternatively, frequency- and pattern-deviation MMNs could originate in different generators. These alternatives were investigated using principal component analysis and signal identification methods. These methods revealed that no common signal space could account for both of the MMNs, indicating different generator sources for the analysis of frequency and pattern deviance. The results suggest separate memory-related processing for auditory frequency and patterns and indicate that the neural circuit of deviance detection varies as a function of the perceptual context.

Adult↗
PubMed1990

[Simulated epileptiform discharges during the replay of a lengthy EEG recording].

Reviewing a longterm-EEG magnet-recording on the video system of the play-back unit "Mobile Oxford Medilog 9000" EEG patterns appeared, which imposed as epileptiform discharges. They seemed to correlate with the paroxysmal clinical disturbances the patient had experienced and noted in a diary, and could be printed out on a normal EEG-apparatus. Following investigations demonstrated the artificial origin of this EEG patterns: They appeared in fact only using the switches of the play-back unit for the fast back- and forward winding. The time-correlation between clinical and electroencephalographic episodes was simulated by the search of selected EEG-sequences based on the clinical episodes noted from the patient.

Diagnostic Errors↗
PubMed2006

Anomalous origin of the left coronary artery from the right side of the aortic valve in Syrian hamsters (Mesocricetus auratus).

This study describes the coronary artery distribution patterns associated with the anomalous origin of the left coronary artery from the right side of the aortic valve in Syrian hamsters. The hearts of 15 affected animals were examined by means of a corrosion-cast technique, histology and scanning electron microscopy. The hamsters belonged to a laboratory inbred colony with a high incidence of coronary artery anomalies and bicuspid aortic valves. The aortic valve was tricuspid in eight hamsters and bicuspid in the other seven. In all cases, the right coronary artery was normal, whereas the left main coronary artery trunk arose from the right aortic sinus or from the right side of the ventral aortic sinus when the aortic valve was bicuspid. In 12 specimens, the left main trunk crossed the infundibular septum and then divided into the left circumflex branch and the obtuse marginal branch. In another specimen, the course of the left main trunk was ventral to the right ventricular outflow tract; in the remaining two, it surrounded the aorta dorsally. In man, some of these distribution patterns may cause myocardial ischaemia and sudden death. The present findings prove that the origin of the left coronary artery from the right aortic sinus occurs in primitive mammals such as the Syrian hamster, suggesting that the defect may occur in other mammalian species. Its possible occurrence should be borne in mind in domestic animals, especially in those with signs of myocardial ischaemia after strenuous activity.

Animals↗
PubMed2003

Pronuclear and morphological features as a cumulative score to select embryos in ICSI (intracytoplasmic sperm injection) cycles according to sperm origin.

PURPOSE: To analyze best parameter to select embryos according to sperm origin in ICSI cycles. METHODS: One hundred seventy-two ICSI cycles were divided among three different groups: A (ejaculated spermatozoa from nonmale factor infertility), B (ejaculated spermatozoa from oligospermia), and C (spermatozoa from azoospermia). Embryos were divided on Day 1 into two patterns: S0 (pronuclei (PN) aligned and close with normal arrangement of nucleoli) and S1 (when these characteristics were absent) and also on transfer day according to morphological features. RESULTS: Relationships of PN patterns related to sperm origin were noted. More S0 embryos were detected with better sperm quality. Higher number of good quality embryos was obtained when male factor was absent. Ejaculated and epididymal spermatozoa provide better quality embryos than do testicular spermatozoa. CONCLUSIONS: PN classification associated with transfer day morphology is valuable additional noninvasive criterion for elective embryo transfer, mainly in the cases with severe male factor.

Abortion, Spontaneous↗
PubMed1994

Consensus viewpoint on management of urinary infections.

Twenty-four general practitioners completed a questionnaire on behalf of their partners in the practices before attending the symposium. The main points that emerged were that trimethoprim was the most popular antibiotic for treatment of acute urinary infection and that the most common duration of treatment was 5 to 7 days. A panel discussion, with audience participation, covered duration of treatment, antibiotic resistance, specimen collection, management of different patient groups and availability of information concerning resistance patterns. Nineteen of the original 24 general practitioners returned the post-meeting questionnaire, and stated that, as a result of what they had heard at the symposium, they were contemplating changing the way in which they managed urinary infections. Information concerning bacteriuria in pregnancy and changing patterns of bacterial resistance to antibiotics were of particular interest.

Anti-Infective Agents, Urinary↗
PubMed1985

Origin binding by a 100,000-dalton super-T antigen from SVT2 cells.

The SVT2 line of simian virus 40-transformed mouse cells expresses little or no wild-type-size A protein (T antigen). Instead, a variant form is produced in these cells that is larger than normal-size A protein. This variant form has an Mr of 100,000 (100K super-T antigen) and is found primarily in complexes with the host-cell-coded p53 protein. Binding of the 100K super-T antigen to simian virus 40 origin region DNA was assayed by immunoprecipitation of super-T antigen-DNA complexes and then digestion with DNase I. DNA sequences associated with super-T antigen were protected from digestion and retained in the immune complex, while unprotected sequences were digested and released. The 100K super-T antigen efficiently protects DNA sequences in the previously defined regions I and II (P. Tegtmeyer, B. A. Lewton, A. L. DeLucia, V. G. Wilson, and K. Ryder, J. Virol. 46:151-161, 1983). Within region II (the origin of replication), the pattern and size of protected fragments are identical for super-T antigen and purified wild-type A protein. Thus, even though super-T antigen is larger than wild-type A protein, both must bind with the same alignment on origin DNA. Furthermore, complexes between the host-cell-coded p53 protein and the 100K super-T antigen also retain the ability to bind in regions I and II.

Antigens, Polyomavirus Transforming↗
PubMed1992

Plasticity of the sympathetic nervous system innervating the cerebral arteries in rats.

In order to investigate the neuroplasticity of the peripheral sympathetic nervous system innervating the cerebral blood vessels, we observed and traced the sprouting nerve fibers originating in the contralateral superior cervical ganglion (SCG) into the previously denervated cerebral arteries following unilateral excision of the SCG and/or decentralization of the contralateral SCG in young rats (4 weeks old). These nerve fibers were labeled anterogradely with wheat germ agglutinin-horseradish peroxidase or stained immunohistochemically with anti-tyrosine hydroxylase antibody. Eight weeks after the right SCG excision, reinnervating nerve fibers originating in the contralateral ganglion formed a circular pattern of nerve plexus only on the wall of the main cerebral arteries of the circle of Willis in the ganglionectomized side. However, the decentralization of the contralateral SCG, which was performed simultaneously with a unilateral SCG excision, prevented the nerve sprouting into the denervated regions. Unilateral decentralization of SCG itself failed to affect their distribution pattern or their density of nerve fibers originating in the ganglion. It is concluded that in the young rat the outgrowth of the sympathetic nerve fibers into the denervated cerebral arteries was strongly impeded by the disconnection of ganglion cells from the central nervous system, while the decentralization alone could not affect the innervation pattern of the postganglionic fibers which have been already built-up in the cerebral arterial system.

Animals↗
PubMed1985

Recurrence after surgery in Crohn's disease. Relationship to location of disease (clinical pattern) and surgical indication.

Among 615 patients with Crohn's disease originally diagnosed at the Cleveland Clinic Foundation from 1966 to 1969, 592 have been followed (96%) for a mean of 13 yr. Of these, 438 had undergone operation. The purpose of this study was to determine how many of these patients had developed recurrences requiring another operation and to relate recurrences to the original anatomic location of disease (the clinical pattern) and surgical indication. Those patients with ileocolic disease had the highest recurrence: 53% compared with 45% for colonic and 44% for small intestinal patterns. Second recurrences were ileocolic pattern 35%, colon 34%, small intestine 38%. The estimated median time of recurrence was similar among these three groups. The presence of internal fistula or perianal disease as an indicator for surgery were associated with a higher likelihood of recurrence and a shortened estimated median time to recurrence. This study supports the concept of conservatism with regard to the management of these two complications for patients with Crohn's disease.

Adult↗
PubMed1991

Morphological differentiation and changes in polypeptide synthesis pattern during regeneration of human epidermal tissue developed in vitro.

By incubating multilayered primary cultures of human keratinocytes in low-calcium medium the suprabasal cell layers can be stripped off leaving a basal cell monolayer. When this monolayer is re-fed normal calcium medium a reproducible series of cell kinetic, morphological, and biochemical changes takes place resulting in the reestablishment of a multilayered tissue. Analysis of cell-cycle-specific proteins indicated that, during regeneration, a large cohort of cells became synchronized undergoing DNA replication after 3 days. Examination of culture morphology at the ultrastructural level confirmed the capacity of the basal cell monolayer to gradually reestablish a multilayered, differentiated epithelium. The ultrastructural appearance at 7 days poststripping was similar to that of unstripped cultures and was indicative of a tissue in steady state. Quantitation of cornified envelope formation at different times during regeneration showed that an increasing proportion of the cells were able to undergo terminal differentiation. In general, the pattern of keratin synthesis in the original epidermal explant labelled in vitro was similar to the pattern observed in human epidermis in vivo; however, in contrast to epidermis in vivo the explant also synthesized the hyperproliferative keratins 6 and 16. The in vitro differentiated keratinocytes showed underexpression of several proteins identified as differentiation markers, whereas several basal cell markers were overexpressed compared to the original explant. In addition, the in vitro differentiated keratinocytes synthesized some new proteins, notably keratins 7, 15 and 19. The basal layer remaining after stripping mainly expressed basal cell markers; however, during recovery, some of the differentiation-specific markers (e.g. keratin 10 and 15) were again expressed together with keratin no. 19, which is also expressed during wound healing in vivo. It is suggested that the present system of regenerating epidermal tissue cultures may serve as an experimental model to investigate certain aspects of the regulation of epidermal tissue homeostasis.

Cell Differentiation↗
PubMed1988

Experimental study of acute coronary sinus thrombosis--clinical references to coronary sinus thrombosis and coronary venography.

The study was carried out to ascertain the effects caused by thrombosis in the coronary venous system. The coronary sinus (CS) of 21 adult mongrel dogs was abruptly obstructed to produce acute CS thrombosis. These dogs were then tested for serial changes of ECG, coronary arterial blood flow (CBF), left ventricular pressure (LVP), serum enzymes originating from the injured myocardium and histological changes of myocardium. Furthermore, the clinical application of a new coronary venography procedure was investigated. The results obtained in these experiments were as follows; (1) When the CS thrombosis was produced by the abrupt obstruction of the sinus, ECG patterns and serum enzymes originating from the myocardium showed changes similar to those of acute myocardial infarction. (2) The histological examinations showed that the changes in myocardial infarction were characteristically similar to those of hemorrhagic infarction. (3) Despite the complete obstruction of the coronary-venous system by thrombosis, the development of thrombosis or obstruction was not observed on the coronary-arterial side. This phenomenon is probably due to the recirculation of blood flow through the Thebesian vessels. (4) The experiment confirmed that the clear coronary venograms were easily obtained, without any risk, by the fixation of a balloon-tipped catheter inside the CS.

Animals↗
PubMed2005

Emergent patterns of growth controlled by multicellular form and mechanics.

Spatial patterns of cellular growth generate mechanical stresses that help to push, fold, expand, and deform tissues into their specific forms. Genetic factors are thought to specify patterns of growth and other behaviors to drive morphogenesis. Here, we show that tissue form itself can feed back to regulate patterns of proliferation. Using micro-fabrication to control the organization of sheets of cells, we demonstrated the emergence of stable patterns of proliferative foci. Regions of concentrated growth corresponded to regions of high tractional stress generated within the sheet, as predicted by a finite-element model of multicellular mechanics and measured directly by using a micromechanical force sensor array. Inhibiting actomyosin-based tension or cadherin-mediated connections between cells disrupted the spatial pattern of proliferation. These findings demonstrate the existence of patterns of mechanical forces that originate from the contraction of cells, emerge from their multicellular organization, and result in patterns of growth. Thus, tissue form is not only a consequence but also an active regulator of tissue growth.

Animals↗
PubMed2002

Multidrug resistance among Enterobacteriaceae is strongly associated with the presence of integrons and is independent of species or isolate origin.

This study investigated the extent to which multidrug resistance (MDR) among Enterobacteriaceae is related to DNA elements called "integrons," whether the relationship is species dependent or origin dependent, and which resistance patterns are associated with integrons. Analysis of 867 nonrepeat isolates comprising 8 species and originating from the community and 23 European hospitals showed a significant relation between MDR and integrons, independent of species or origin. Although resistance to each tested antimicrobial agent was significantly associated with integrons, only resistance to sulfamethoxazole, cotrimoxazole, gentamicin, tobramycin, ampicillin, piperacillin, and cefuroxime predicted the presence of integrons. Combined resistance to both ampicillin and sulfamethoxazole-trimethoprim was the starting point for the development of resistance to additional beta-lactams, aminoglycosides, cephalosporins, and ciprofloxacin, a development paralleled by an increasing prevalence of integrons. The acquisition of resistance genes is not random, and the transfer of integron-carrying elements plays a dominant role in the development of MDR by Enterobacteriaceae.

Anti-Bacterial Agents↗
PubMed1992

A clinicopathologic study on the diffuse malignant lymphoma--a morphologic and immunophenotypic analysis in 62 patients at Harbor-UCLA Medical Center.

In order to compare the prognoses of patients with diffuse malignant lymphomas on the basis of histology and immunophenotypes, we retrospectively studied 62 cases of diffuse lymphoma arising in lymph nodes. We also evaluated the reactivity patterns of monoclonal antibodies (MoAb) LN1, LN2 and LN3 to determine the criteria for making a differential diagnosis in B cell lymphomas. The immunologic phenotypes were determined by the avidin biotin peroxidase complex method, using frozen or paraffin fixed tissues. The majority (66.3%) were B cell with the remaining 20.9% being T cell and 12.9% were non-B, non-T cell lineage. Immunological heterogeneity was found especially in the mixed small and large cell and the immunoblastic lymphomas. There was no significant difference between B- and T-cell lymphomas with respect to survival and death (P > 0.05). Histologically 79% (49/62) of the lymphoma was large cell and 21% (13/62), small cell lymphoma. There was a difference in prognosis between low, intermediate and high-grade of lymphomas. However there were no significant differences among the subtypes of the diffuse aggressive lymphomas. Factors associated with poor prognosis were advanced stages (P < 0.025) and histology of the malignant lymphomas. MoAb LN1, LN2 and LN3 gave positive staining in 83.3%, 91.7% and 60% of B cell lymphomas, respectively. The most common phenotypic pattern in B cell lymphomas was LN1+, LN2+, LN3+/-, suggestive of follicular center cell origin. As a panel, phenotypic patterns of MoAb LN1, LN2 and LN3 may be useful in differentiation of follicular center cell lymphoma from others.

Adolescent↗
PubMed2000

Multiple Beam Interference Confocal Microscopy: Tool for Morphological Investigation of a Living Spermatozoon.

The interference pattern obtained from a multiple internal reflection of a spermatozoon, sandwiched between the glass plate and the cover plate, was focused on the objective of a scanning confocal microscope. According to optical path differences, morphological details were revealed. The combined features, namely improved resolution in z axis, originating from the interference pattern and the optical sectioning of the confocal scanning system, enhanced the resolution and contrast in an impressive manner. These features permitted unprecedented images of the spermatozoon to be obtained at 0.1 µm optical sectioning and reconstruction of three-dimensional (3-D) images. With the help of optical sectioning, it was possible to estimate the thickness and the morphological details of the spermatozoon.

Journal Article↗
PubMed2002

Geometric Clutch model version 3: the role of the inner and outer arm dyneins in the ciliary beat.

The Geometric Clutch model of ciliary and flagellar beating uses the transverse force (t-force) that develops between the outer doublets of the axoneme as the regulator for activating and deactivating the dynein motors and organizing the flagellar beat. The version of the model described here adds detail to the formulations used in the two previous versions as follows: (1) In place of two opposing sets of dyneins, the new model has four sets of dyneins, corresponding to two sets on each side of the axoneme acting in series. (2) The four sets of dyneins are each subdivided into two ranks representing inner and outer arm dyneins. (3) The force produced by each dynein is governed by a force-velocity relationship that is independently specified for the inner and outer arms. Consistent with the original model, the new version of the Geometric Clutch model can simulate both the effective and recovery stroke phases of the ciliary beat using a single uniform algorithm. In addition, the new version can operate with the outer arms disabled. Under this condition, the simulation exhibits a beat pattern similar to the original but the beat frequency is reduced to approximately one third. These results are contingent on using force-velocity relationships for the inner and outer arms similar to those described by Brokaw [1999: Cell Motil. Cytoskeleton 42:134-148], where the inner arms contribute most of the driving force at low shear velocities. This constitutes the first examination of the effects of the force-velocity characteristics of dynein on a cilia-like beat in a theoretical framework.

Algorithms↗
PubMed2002

Characterization and tissue-specific expression of human GSK-3-binding proteins FRAT1 and FRAT2.

We have isolated the entire coding sequence of human FRAT2 (frequently rearranged in advanced T-cell lymphomas-2). It exhibits appreciable amino acid identity to FRAT1 (77%) which was initially isolated as frequently being overexpressed in a murine leukemia virus insertion model in murine tumors. FRAT proteins are thought to play a role in Wnt signaling. They can bind to glycogen synthase kinase-3 (GSK-3) and Dishevelled, two proteins involved in Wnt signal transduction. Both hFRAT1 and hFRAT2 are intronless genes localized to the same portion of chromosome 10q24.1 and separated by only 10.7 kb. In a broad range of human tissues FRAT1 and FRAT2 are readily detected and expressed in a near identical pattern. Both species are repressed when the human embryonal carcinoma cell line, NT2/D1, is induced to differentiate with all-trans retinoic acid (RA). This treatment had no appreciable effect on FRAT levels in two other RA-sensitive cell lines that were not of germ cell tumor origin. The overlapping expression patterns suggest these two genes share a regulatory region. Both FRAT genes exhibited three species of mRNA, which varied in representation between tissues. When transiently overexpressed in COS-1 cells, the FRAT proteins were detected in the cytosol and concentrated in the nucleus. Both hFRAT1 and hFRAT2 are implicated in the selective modulation of GSK-3 activity via the Wnt signaling pathway. This study provides a foundation from which to examine the role these proteins play in Wnt-dependent and -independent processes.

Adaptor Proteins, Signal Transducing↗