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Neuroimaging of mitochondrial disorders.

Mitochondrial disease is frequently a multisystem disorder which often involves the central nervous system. Imaging finding although diverse are characterized by focal lesions with T2 hyperintensity, which may be most evident on FLAIR imaging and often progress to atrophy. Deep brain structures including brainstem and basal ganglia structures are particularly vulnerable though white matter and cortex may also be involved. In this paper we describe in detail the imaging features of the spectrum of mitochondrial diseases and suggest a scoring technique for recording severity and extent of brain involvement. Although there is overlap between the imaging features of disease phenotypes, magnetic resonance imaging may be useful in supporting the clinical diagnosis. There is little correlation between molecular defect and imaging findings with some noticeable exceptions such as the MELAS syndrome.

Journal Article↗

Evidence for the direct involvement of the rhinovirus canyon in receptor binding.

Evidence is presented that indicates a deep crevice located on the surface of human rhinovirus type 14 is involved in virion attachment to cellular receptors. By using mutagenesis of an infectious cDNA clone, 11 mutants were created by single amino acid substitutions or insertions at positions 103, 155, 220, 223, and 273 of the structural protein VP1. Seven of the recovered mutants had a small plaque phenotype and exhibited binding affinities significantly lower than wild-type virus. One mutant, in which glycine replaced proline at amino acid position 155, showed a greatly enhanced binding affinity. Single-cycle growth kinetics suggested that 5 of the mutants had delayed growth cycles due to intracellular deficiencies apart from receptor binding.

HeLa Cells↗

Differential modulation of myosin heavy chain phenotype in an inactive extensor and flexor muscle of adult rats.

The effects of chronic neuromuscular inactivity on the phenotype and size of muscle fibres in a fast ankle extensor (medial gastrocnemius, MG) and a fast ankle flexor (tibialis anterior, TA) muscle of the rat hindlimb were determined. Inactivity was produced by spinal cord isolation (SI), i.e. complete spinal cord transections at a mid-thoracic and high sacral level and bilateral deafferentation between the transection sites. After 90 days of SI, the MG and TA muscle weights were 53 and 45% lower than in age-matched controls. Overall mean fibre sizes in the deep (close to the bone) and superficial (away from the bone) regions were approximately 60 and 65% smaller in the MG and approximately 40 and 50% smaller in the TA of SI than control rats, respectively. The myosin heavy chain (MHC) composition shifted towards the faster isoforms after SI: the MG showed an increase in both types IIx (20%) and IIb (23%), whereas the TA showed a marked increase in type IIx (94%) and a decrease in type IIb (18%) MHC. Both muscles in SI rats showed no type IIa and only one MG muscle had approximately 5% type I MHC. These results show that prolonged inactivity has a stronger effect on a fast extensor compared with a fast flexor in the rat hindlimb. The larger decrease in mass and fibre size in the MG than the TA most probably reflects the larger impact of chronic inactivity on the normally more highly recruited extensor than flexor muscle. The primary shift to type IIb MHC in the MG and type IIx MHC in the TA indicate a different default mode for an inactive extensor vs. flexor muscle, and may reflect differing activity-independent neural influences, i.e. neurotrophic factors, on muscle fibre phenotype in extensors vs. flexors.

Animals↗

Prenatally detected trisomy 4 and 6 mosaicism--cytogenetic results and clinical phenotype.

We report on a live-born male with 46,XY/47,XY+4/47,XY,+6 mosaicism. Trisomy 4 mosaicism was detected by karyotyping chorionic villus samples (CVS) and was confirmed by the analysis of 16 metaphases obtained from cultured amniotic fluid cells. Eight metaphases were normal (46,XY), two had trisomy 4 (47,XY,+4), and two had trisomy 6 (47,XY,+6). Two postnatal chromosomal analyses of blood lymphocytes at birth and at the age of one week were normal. Chromosomal analysis of cultured skin fibroblasts from the right inguinal region at the age of 12 months revealed trisomy 4 (47,XY,+4) in 49 metaphases, trisomy 6 (47,XY,+6) in 2 metaphases, and a normal karyotype (46,XY) in 49 cells of the 100 analyzed metaphases, respectively. The main clinical findings consist of prenatal growth retardation, hypoplasia of the right side of the face, a dysplastic and posteriorly rotated right ear, a high vaulted palate, retrognathia, aplasia of the right thumb, hypoplasia of the fingernails, a deep sacral dimple, and patchy skin hypopigmentation of the right leg. When last seen at the age of 14 months, his development was nearly normal. Five patients with trisomy 4 mosaicism have been reported previously, but none with an additional trisomy 6 mosaicism.

Abnormalities, Multiple↗

In vivo confocal microscopic evaluation of Langerhans cell density and distribution in the normal human corneal epithelium.

PURPOSE: To examine the density and distribution of Langerhans cells (LCs) in the corneal epithelium of healthy volunteers. METHODS: Two hundred eyes of 112 healthy volunteers (age 21-81 years) without history of ocular inflammation or surgery were examined in vivo with the combination of the Heidelberg Retina Tomograph II and the Rostock Cornea Module. For statistical analysis data of one eye per volunteer were used, with random selection of one eye in those volunteers in whom both eyes were studied. RESULTS: As studied by in vivo confocal microscopy, 31.3% of all volunteers presented with LCs (24 volunteers with both eyes studied and 11 volunteers with only one eye studied). In 30 of these 35 volunteers, LCs were found in both the central and peripheral corneal epithelium. More than 50% of male volunteers with LCs were younger than 30 years; in contrast, almost two thirds of females with LCs were above 50 years in age. The density of LCs in the periphery of the cornea (98+/-8 cells/mm2; range 0-208 cells/mm2) was significantly (p<0.001) greater than in the central part (34+/-3 cells/mm2; range 0-64 cells/mm2). LCs were located at depths of 35-60 microm, with different frequency. While LCs were sparse at the level of deep intermedial cells (5.7% of the volunteers), 11.4% of the volunteers presented with LCs within the level of basal epithelial cells and most of the eyes (82.9%) had LCs at the level of basal epithelial cells and subbasal nerve plexus. Moreover, LCs presented as either large cells bearing long processes or smaller cells lacking cell dendrites, presumably indicating mature and immature phenotype, respectively. CONCLUSION: The Heidelberg Retina Tomograph II in combination with the Rostock Cornea Module enables in vivo assessment of density and distribution of LCs in the corneal epithelium, providing insight into human eye immunology. These data may now provide a suitable basis for further investigations in ocular pathology.

Adult↗

The presence of fluconazole-resistant Candida dubliniensis strains among Candida albicans isolates from immunocompromised or otherwise debilitated HIV-negative Turkish patients.

The newly described species Candida dubliniensis phenotipically resembles Candida albicans in many respects and so it could be easily misidentified. The present study aimed at determining the frequency at which this new Candida species was not recognized in the authors' university hospital clinical laboratory and to assess antifungal susceptibility. In this study, six identification methods based on significant phenotypic characteristics each proposed as reliable tests applicable in mycology laboratories for the differentiation of the two species were performed together to assess the clinical strains that were initially identified as C. albicans. Only the isolates which have had the parallel results in all methods were assessed as C. dubliniensis. One hundred and twenty-nine C. albicans strains isolated from deep mycosis suspected patients were further examined. Three of 129 C. albicans (2 from oral cavity, 1 from sputum) were reidentified as C. dubliniensis. One of the strains isolated from oral cavity and that from the sputum were obtained at two months intervals from the same patient with acute myeloid leukemia, while the other oral cavity strain was obtained from a patient who had previously been irradiated for a laryngeal malignancy. Isolates were all susceptible in vitro to amphotericin B, with the MIC range 0.125 to 0.5 &mgr;g/ml, resistant to fluconazole, with MICs >/=64 &mgr;g/ml, and resistant to ketoconazole, with MICs >/=16 &mgr;g/ml, dose-dependent to itraconazole with a MIC range 0.25-0.5 &mgr;g/ml, and susceptible to flucytosine, with a MIC range 1-4 &mgr;g/ml.

Journal Article↗

An overview of the heparin-induced thrombocytopenia syndrome.

Heparin-induced thrombocytopenia (HIT) is caused by heparin-dependent, platelet-activating IgG antibodies that increase thrombin generation in vivo, producing a prothrombotic phenotype. In addition to platelet activation, there is in vitro evidence that activation of endothelium and monocytes occurs, perhaps directly by HIT antibodies, but more likely through activated platelet (or microparticle)-endothelial-leukocyte interactions. Patients with cardiac disease receiving heparin present important diagnostic and therapeutic issues when unexpected thrombocytopenia arises. Concomitant vascular disease burden and intravascular catheter use further increase risk of HIT-associated arterial thrombosis in this patient population. Whether arterial thrombosis simply reflects the "hypercoagulability state" of HIT interacting with diseased or injured arteries, or whether arterial "white clots" reflect additional prothrombotic effects of HIT via endothelial and monocyte activation, remains uncertain. Patients with HIT can also develop deep-vein thrombosis, which can progress to limb loss if coumarin (warfarin) leads to severe protein C depletion (coumarin-induced venous limb gangrene). Therapy for patients strongly suspected to have HIT should focus on inhibiting thrombin (or its generation) pharmacologically. Two direct thrombin inhibitors (lepirudin, argatroban) are approved for treating HIT. When using these agents, coumarin anticoagulation should be delayed pending substantial resolution of thrombocytopenia, before cautiously introducing overlapping coumarin therapy.

Antibodies↗

Chromosome 1p36 deletions: the clinical phenotype and molecular characterization of a common newly delineated syndrome.

Deletions of the distal short arm of chromosome 1 (1p36) represent a common, newly delineated deletion syndrome, characterized by moderate to severe psychomotor retardation, seizures, growth delay, and dysmorphic features. Previous cytogenetic underascertainment of this chromosomal deletion has made it difficult to characterize the clinical and molecular aspects of the syndrome. Recent advances in cytogenetic technology, particularly FISH, have greatly improved the ability to identify 1p36 deletions and have allowed a clearer definition of the clinical phenotype and molecular characteristics of this syndrome. We have identified 14 patients with chromosome 1p36 deletions and have assessed the frequency of each phenotypic feature and clinical manifestation in the 13 patients with pure 1p36 deletions. The physical extent and parental origin of each deletion were determined by use of FISH probes on cytogenetic preparations and by analysis of polymorphic DNA markers in the patients and their available parents. Clinical examinations revealed that the most common features and medical problems in patients with this deletion syndrome include large anterior fontanelle (100%), motor delay/hypotonia (92%), moderate to severe mental retardation (92%), growth delay (85%), pointed chin (80%), eye/vision problems (75%), seizures (72%), flat nasal bridge (65%), clinodactyly and/or short fifth finger(s) (64%), low-set ear(s) (59%), ear asymmetry (57%), hearing deficits (56%), abusive behavior (56%), thickened ear helices (53%), and deep-set eyes (50%). FISH and DNA polymorphism analysis showed that there is no uniform region of deletion but, rather, a spectrum of different deletion sizes with a common minimal region of deletion overlap.

Abnormalities, Multiple↗

Ploidy in invasive colorectal cancer. Implications for metastatic disease.

A retrospective study was performed to determine the ploidy of superficial (above muscularis propria) and deep (below muscularis propria) biopsy specimens from the primary colorectal cancer of 88 patients with Dukes Stage C2 and D colorectal tumors. The ploidy of lymph node and liver metastases was compared with that of the superficial and deep specimen from the corresponding primary tumor. Among the tumors studied, 78% exhibited nondiploid stemlines. In 19% of the tumors, the ploidy of the superficial biopsy differed from that of the deep biopsy. Among these discordant tumors, all of the deep biopsy specimens corresponded in ploidy to the liver metastases, whereas most of the superficial specimens were similar in ploidy to the lymph node metastases. Our observations suggest that measurement of a single site may not be sufficient to detect nondiploid stemlines within a tumor. They also suggest that measurement of deeper parts of invasive tumors may be more reflective of the phenotype of distant metastases than measurement of superficial specimens.

Colorectal Neoplasms↗

Reduced influence of the ipsilateral ear on spatial tuning of auditory neurons in the albino superior colliculus: a knock-on effect of anomalies of the acoustic chiasm?

Auditory brainstem abnormalities affecting decussation patterns and nuclei involved in the acoustic chiasm exist in a variety of albino mammals, suggesting that binaural processes underlying spatial hearing may be disrupted in these mutants. To evaluate this we have compared the contribution of the two ears in albino and normally pigmented guinea pigs to the spatial tuning of auditory neurons in the deep layers of the superior colliculus (SC). Broadband noise stimuli at threshold and at suprathreshold intensities were presented from different azimuthal loudspeaker locations under free-field anechoic conditions, and auditory receptive fields were plotted before, during and after occluding the ipsilateral ear. We show that the deep layers of the albino SC contain a map of contralateral auditory azimuth along its anteroposterior axis, which is aligned with the visual map in the superficial layers above, just as in normal animals. We also show that threshold spatial responses are elicited only via the contralateral ear and at similar stimulus intensities (mean approximately 30 dB SPL) in the two pigmentation phenotypes. The mechanisms that maintain spatial tuning at sound intensities of 10-40 dB above threshold, however, differ markedly in these animals. Plugging the ipsilateral ear in normal guinea pigs caused significant expansions of their auditory receptive fields and loss of directional tuning, but in the albinos occlusion had little effect on these spatial properties. The results suggest that while spatial selectivity for relatively loud sounds among SC neurons is normally maintained via the binaural combination of contralateral excitatory drive and ipsilateral inhibition, it is achieved in albinos almost exclusively by monaural input from the contralateral ear. This finding is consistent with an excessive contralateral ear dominance of higher levels of the albino auditory system caused by anomalies of their acoustic chiasm, analogous to the monocular dominance of the visual system that results from excessive axon crossing at the optic chiasm in these animals.

Animals↗

Human herpesvirus type 8 and epstein-barr virus-associated cutaneous lymphoma taking anaplastic large cell morphology in a man with HIV infection.

Human herpesvirus type 8 (HHV-8, Kaposi's sarcoma-associated herpesvirus)-positive lymphoma taking anaplastic large cell morphology in the skin is described in a 46-year-old man with AIDS. Multiple erythematous nodules appeared on the trunk and extremities during the treatment of AIDS. Histological examination of cutaneous nodules showed dense infiltration of CD30 + atypical lymphoid cells in the deep dermis. Immunoglobulin JH gene rearrangement was detected in these lymphoma cells. Both Epstein-Barr virus-encoded small RNA and HHV-8 mRNA (T1.1/nut-1) were detected in these lymphoma cells by in situ hybridization. Remarkable retention of the pericardial fluid was observed at the same time that cutaneous lesions grew, and lymphoma cells in the pericardial fluid showed the same phenotype as the cutaneous lymphoma. Chemotherapy with cyclophosphamide, doxorubicin, vincristine and prednisone effectively reduced both the cutaneous nodules and pericardial fluid. However, the patient died 4 months after diagnosis because of cytomegalovirus infection. As far as we know, this is the first report of an HHV-8-positive cutaneous lymphoma taking anaplastic large cell morphology. This case suggests the association of AIDS-related anaplastic large cell lymphoma with HHV-8.

Herpesvirus 4, Human↗

Endothelial diaphragmed fenestrae: in vitro modulation by phorbol myristate acetate.

Cultured microvascular endothelial cells isolated from fenestrated capillaries have been shown to express many properties of their in vivo differentiated phenotype, yet they contain very few diaphragmed fenestrae. We show here that treatment of capillary endothelial cells with the tumor promoter, 4 beta-phorbol 12-myristate 13-acetate, induces more than a fivefold increase in the frequency of fenestrae per micron 2 of cell surface, as determined from a quantitative evaluation on freeze-fracture replicas. In quick-frozen, deep-etched preparations, the endothelial fenestrae appeared to be bridged by a diaphragm composed of radial fibers interweaving in a central mesh, as previously observed in vivo. These results indicate that diaphragmed fenestrae are inducible structures, and provide an opportunity to study them in vitro.

Adrenal Cortex↗

Delayed posthypoxic demyelination. Association with arylsulfatase A deficiency and lactic acidosis on proton MR spectroscopy.

Delayed demyelination is a rare and poorly understood complication of hypoxic brain injury. A previous case report has suggested an association with mild-to-moderate deficiency of arylsulfatase A. We describe a 36-year-old man who recovered completely from an episode of hypoxia related to drug overdose, and 2 weeks later progressed from a confusional state to deep coma. MRI showed diffuse white matter signal changes, and brain biopsy demonstrated a noninflammatory demyelinating process. Proton magnetic resonance spectroscopy revealed elevated choline and lactate and reduced N-acetyl aspartate signal in the affected white matter, consistent with demyelination and a shift to anaerobic metabolism. Arylsulfatase A activity from peripheral leukocytes was approximately 50% of normal, consistent with a "pseudodeficiency" phenotype. These findings confirm the hypothesis that relative arylsulfatase A deficiency predisposes susceptible individuals to delayed posthypoxic leukoencephalopathy and implicates lactic acidosis in the pathogenesis of this disorder.

Acidosis, Lactic↗

Desulfovibrio profundus sp. nov., a novel barophilic sulfate-reducing bacterium from deep sediment layers in the Japan Sea.

Several strains of a strictly anaerobic, vibrio-shaped or sigmoid, sulfate-reducing bacterium were isolated from deep marine sediments (depth, 80 and 500 m) obtained from the Japan Sea (Ocean Drilling Program Leg 128, site 798B). This bacterium was identified as a member of the genus Desulfovibrio on the basis of the presence of desulfoviridin and characteristic phospholipid fatty acids (iso 17:1 omega 7 and iso 15:0), the small number of growth substrates utilized (lactate, pyruvate, and hydrogen), and 16S rRNA gene sequence analysis data. Based on data for 16S rRNA sequences (1,369 bp), all of the Japan Sea strains were identical to each other and were most closely related to Desulfovibrio salexigens and less closely related to Desulfovibrio desulfuricans (levels of similarity, 91 and 89.6%, respectively). There were, however, considerable phenotypic differences (in temperatures, pressures, and salinities tolerated, growth substrates, and electron donors) between the Japan Sea isolates and the type strains of previously described desulfovibrios, as well as important differences among the Japan Sea isolates. The Japan Sea isolates were active (with sulfide production) over a wide temperature range (15 to 65 degrees C) and a wide sodium chloride concentration range (0.2 to 10%) (moderate halophile), and they were barophiles that were active at pressures up to about 40 MPa (400 atm). The optimum pressures for activity corresponded to the calculated pressures at the depths from which the organisms were isolated (for isolates obtained at depths of 80 and 500 m the optimum activities occurred at 10 and 15 MPa, respectively [100 and 150 atm, respectively]). This confirms that the organisms came from deep sediments and indicates that they are well-adapted for deep sediment conditions, which is consistent with other characteristics (utilization of hydrogen, fermentation, and utilization of ferric iron and organic sulfonates as electron acceptors). We propose that Japan Sea isolate 500-1 is the type strain of a new species, Desulfovibrio profundus.

Base Sequence↗

Sphingomonas alaskensis sp. nov., a dominant bacterium from a marine oligotrophic environment.

Seven Gram-negative strains, isolated in 1990 from a 10(6)-fold dilution series of seawater from Resurrection Bay, a deep fjord of the Gulf of Alaska, were identified in a polyphasic taxonomic study. Analysis of 16S rDNA sequences and DNA-homology studies confirmed the phylogenetic position of all strains in the genus Sphingomonas and further indicated that all of the strains constitute a single homogeneous genomic species, distinct from all validly described Sphingomonas species. The ability to differentiate the species, both phenotypically and chemotaxonomically, from its nearest neighbours justifies the proposal of a new species name, Sphingomonas alaskensis sp. nov., for this taxon. Strain LMG 18877T (= RB2256T = DSM 13593T) was selected as the type strain.

Bacterial Typing Techniques↗

Polycystic kidneys, pancreatic cysts, and cystadenomatous bile ducts in the oral-facial-digital syndrome type I.

Oral-facial-digital syndrome type I is a group of X-linked dominant conditions, lethal in utero in male individuals. Internal anomalies are less well documented than are external findings. We report a case of typical phenotype and absent family history of kidney disease in a 15-year-old white girl (46,XX) who died of renal failure and massive cerebral hemorrhage. At necropsy, the kidneys were greatly enlarged but of fairly normal shape. The cortex was replaced by thin-walled spherical cysts, 0.5 to 2.0 cm in diameter; the majority of the smaller cysts were located deep in the cortex, and the medulla contained lesser numbers of larger cysts. No distal urinary tract obstruction was present. Microdissection revealed cysts and diverticula located in all segments of the nephrons and collecting ducts. Uninvolved nephrons showed diffuse hypertrophy. These findings were correlated with immunoperoxidase stains using peanut lectin, Lotus tetragonolobus agglutinin, antibodies to cytokeratins, stage-specific embryonic antigen-1, Tamm-Horsfall protein, and epithelial membrane antigen. Other visceral anomalies included biliary cystadenomatous proliferation in the liver and pancreatic cysts. The renal changes are similar to those of autosomal dominant (adult-type) polycystic disease.

Adolescent↗

Cerebellar disorganization characteristic of reeler in scrambler mutant mice despite presence of reelin.

Analysis of the molecular basis of neuronal migration in the mammalian CNS relies critically on the discovery and identification of genetic mutations that affect this process. Here, we report the detailed cerebellar phenotype caused by a new autosomal recessive neurological mouse mutation, scrambler (gene symbol scm). The scrambler mutation results in ataxic mice that exhibit several neuroanatomic defects reminiscent of reeler. The most obvious of these lies in the cerebellum, which is small and lacks foliation. Granule cells, although normally placed in an internal granule cell layer, are greatly reduced in number ( approximately 20% of normal). Purkinje cells are also reduced in number, and the majority are located ectopically in deep cerebellar masses. There is a small population of Purkinje cells ( approximately 5% of the total) that occupy a Purkinje cell layer between the molecular and granule cell layers. Despite this apparent disorganization of Purkinje cells, zebrin-positive and zebrin-negative parasagittal zones can be delineated. The ectopic masses of Purkinje cells are bordered by the extracellular matrix protein tenascin and by processes containing glial fibrillary acidic protein. Antibodies specific for these proteins also identify a novel midline raphe structure in both scrambler and reeler cerebellum that is not present in wild-type mice. Thus, in many respects, the scrambler cerebellum is identical to that of reeler. However, the scrambler locus has been mapped to a site distinct from that of reelin (Reln), the gene responsible for the reeler defect. Here we find that there are normal levels of Reln mRNA in scrambler brain and that reelin protein is secreted normally by scrambler cerebellar cells. These findings imply that the scrambler gene product may function in a molecular pathway critical for neuronal migration that is tightly linked to, but downstream of, reelin.

Animals↗

Functional traits and plasticity in response to light in seedlings of four Iberian forest tree species.

We investigated the differential roles of physiological and morphological features on seedling survivorship along an experimental irradiance gradient in four dominant species of cool temperate-Mediterranean forests (Quercus robur L., Quercus pyrenaica Willd., Pinus sylvestris L. and Pinus pinaster Ait.). The lowest photochemical efficiency (F(v)/F(m) in dark-adapted leaves) was reached in deep shade (1% of full sunlight) in all species except Q. robur, which had the lowest photochemical efficiency in both deep shade and 100% of full sunlight. Species differed significantly in their survival in 1% of full sunlight but exhibited similar survivorship in 6, 20 and 100% of full sunlight. Shade-tolerant oaks had lower leaf area ratios, shoot to root ratios, foliage allocation ratios and higher rates of allocation to structural biomass (stem plus thick roots) than shade-intolerant pines. Overall phenotypic plasticity for each species, estimated as the difference between the minimum and the maximum mean values of the ecophysiological variables studied at the various irradiances divided by the maximum mean value of those variables, was inversely correlated with shade tolerance. Observed morphology, allocation and plasticity conformed to a conservative resource-use strategy, although observed differences in specific leaf area, which was higher in shade-tolerant species, supported a carbon gain maximization strategy. Lack of a congruent suite of traits underlying shade tolerance in the studied species provides evidence of adaptation to multiple selective forces. Although the study was based on only four species, the importance of ecophysiological variables as determinants of interspecific differences in survival in limiting light was demonstrated.

Light↗