Atomic force microscopy of the cornea and sclera

We report the first investigation of the extracellular matrix of cornea and sclera using an atomic force microscope (AFM), and evaluate the potential of this new technique. We were able to obtain 2-3 nanometre resolution of both tissues in a condition close to their native state. The AFM was able to resolve surface features on the collagen fibrils, as well as providing unique images of crossbridge structures between collagen fibrils in both cornea and sclera.

[An experimental study of middle ear implantable hearing device]

The partially middle ear implantable hearing device was designed and tested in 7 cats with conductive hearing loss and 5 cats with mixed hearing loss. It was composed of sound processor, connector and ossicular vibrator. The ossicular vibrator was made from piezoelectric ceramic bimorph which was constructed in the form of flat chip 6mm in length, 1mm in width and 0.5mm in thickness. The incus of cat was removed and the lip attachment of the vibrator was attached to the head of the stapes. The base of the vibrator was fixed to the bone wall of bulla with medical glue. The average values of the response threshold of ABR evoked by click via this vibrator got reduction of 37dB and 39dB respectively in conductive hearing loss group and mixed hearing loss group. The gain curve of hearing was flat in the range from 0.5 to 8kHz frequencies. The ABRs evoked by click via ossicular vibrator was similar to that recorded preoperatively in the wave shape. This result indicates that this device is a highly efficient sound conducting divice to inner ear.

Eosinophilic pustular folliculitis in three atopic children with hypersensitivity to Dermatophagoides pteronyssinus

Three children will be described who present recurrent episodes of pruritic papulopustular follicular lesions on the face, the extremities and the trunk. The episodes lasted for 1-3 months with intermittent remission. Each flare was accompanied by hypereosinophilia and an increased total IgE titer. RAST and prick tests were positive for Dermatophagoides pteronyssinus (DPT). Laboratory tests disclosed no infectious or parasitic etiology. Histological examination showed eosinophilic pustular folliculitis (EPF) in each of the 3 cases. The lesions responded well to topical corticosteroids. The aim of this article is to underline the importance of hypersensitivity reactions (in these particular cases to DPT) in the pathogenesis of EPF.

[Systemic sarcoidosis with cutaneous lesions: literature review]

Sarcoidosis is a systemic disease of unknown etiology. The diagnosis is based on consistent clinical, biological and radiological findings supported by histologic evidence of noncaseating epithelioid granulomas. Skin lesions occur in about a quarter of patients with sarcoidosis. The purpose of this article is to analyse through the clinical presentation of dermatological lesions, a potential link with systemic disease.

Degradation of endogenous plasma membrane fibronectin concomitant with Treponema denticola 35405 adhesion to gingival fibroblasts

Treponema denticola adhesion and degradation of fibronectin (Fn) on human gingival fibroblasts (HGF) were studied by immunofluorescence and enzyme-linked immunosorbent assays. The number of adherent bacteria increased and the amount of immunoreactive Fn decreased as a function of increasing T. denticola concentration. The distribution of cell-bound Fn was punctate in micrographs. Anti-human Fn impaired bacterial adhesion to HGF. Phenylmethylsulfonyl fluoride inhibited Fn degradation but not adhesion. Sonicated extracts and diluted spent growth medium degraded HGF Fn but, unlike intact T. denticola cells, they hardly stimulated F-actin rearrangements.

[Physiopathology of pruritus]

Itching is the predominant symptom of inflammatory skin diseases. Present evidence indicates that histamine and unidentified peptides mediate itching. No evidence is available that lymphokines or cytokines play a direct role as itch mediators. Prostaglandins serve an important synergistic function in itching. Evidence points to a role for opioid peptides of the central nervous system in the perception of itch and as direct mediators. Pruritus may be a prominent symptom in uraemia, biliary obstruction, atopic dermatitis and neoplasia.

Effect of iron regulation on expression and hemin-binding function of outer-sheath proteins from Treponema denticola

The effect of the iron-chelating compounds EDDA and BPD on polypeptide regulation in the putative oral pathogen Treponema denticola was studied. SDS-PAGE analysis of the T. denticola strains grown in the presence of EDDA or BPD, i.e. iron-limiting environmental conditions, revealed the expression of 44 and 43 kDa polypeptides in the outer sheath, a 73 kDa polypeptide in the cell membrane, and a 16 kDa polypeptide in the soluble cell fraction. The hemin-binding activity of purified outer sheaths from T. denticola TD-4 grown in the presence of 6.4 mM EDDA was significantly greater than that observed in control (absence of EDDA) outer sheaths. Both activities were inhibited by proteinase K. SDS-PAGE, LDS-PAGE and TMBZ staining revealed the 44 and 43 kDa outer-sheath polypeptides to be expressed by T. denticola strains GM-1. MS-25, ATCC 33520 and ATCC 33404 (TD-4), strains which possessed strong hemin-binding activity. The 44 kDa hemin-binding polypeptide was purified by 1% CHAPS solubilization, HPLC, and SDS-preparative electrophoresis. N'-terminal sequence analysis indicated the purified 44 kDa polypeptide to belong to a new, undescribed group of polypeptides possessing hemin-binding activity.

Restoration of normal ultrastructure after expression of the alpha 1 subunit of the L-type Ca2+ channel in dysgenic myotubes

Muscular dysgenesis (mdg) is a spontaneous mutation affecting the alpha 1 subunit of the skeletal L-type Ca2+ channel. mdg/mdg mice suffer from a skeletal muscle disease characterised by low levels of the slow Ca2+ current, lack of contractile activity, and immature organisation of skeletal muscle. Microinjections of a cDNA encoding alpha 1 into mutant myotubes restore excitation-contraction coupling. We checked here that dysgenic myotubes transfected with expression vectors, including a full-length alpha 1 cDNA, also recover normal ultrastructural features. Transfection of alpha 1 cDNA partially deleted on the 5' end leads to the recovery of a good structural organisation without any improvement in the mutant physiological phenotype. These results suggest that: (i) the proper expression of alpha 1 is required for the full muscle differentiation of muscular dysgenesis myotubes, and (ii) portions of the alpha 1 molecule may be involved in the structural organisation of a muscle fiber, independent of its known functional properties.

Recombinant murine serum amyloid A from baculovirus-infected insect cells: purification and characterization

Serum amyloid A (SAA) is an extremely sensitive acute-phase reactant and precursor to the subunit protein in reactive amyloid deposits. Although the mouse has long served as an informative experimental model, both the function of SAA and the pathogenic mechanism of amyloid formation remain unknown. The production of SAA by a heterologous system was pursued as means of generating readily-renewable amounts of SAA of defined sequence. Murine SAA2 has been expressed in and purified from baculovirus-infected insect cells. Using the transfer vector pBlueBac, SAA2 cDNA was cloned into baculovirus DNA such that expression was under the control of the polyhedrin promoter. Lysates prepared from infected cells contained three amyloid A-immunoreactive forms which accumulated intracellularly over a three day periods. The form having the lowest relative molecular mass, 12.5 kDa, co-migrated in SDS-polyacrylamide gels with the SAA2 present in murine acute-phase serum. Recombinant SAA2 was purified by Sepharose CL-6B chromatography followed by chromatofocusing between pH 8 and pH 5. Amino-terminal sequencing of the purified 12.5 kDa sample confirmed the first 20 residues of mature murine SAA2. After incubation with normal mouse serum, purified recombinant SAA2 fractionated exclusively with lipoprotein complexes, suggesting that it was bound to HDL. Based on this observation, we believe that recombinant SAA can serve as a suitable substitute for the native protein in physiologically relevant studies.

[Detection of Helicobacter pylori in human saliva by using nested polymerase chain reaction]

Epidemiologic studies suggest person to person spread of Helicobacter pylori (H. pylori), but the exact mechanism is unknown. Spread through oral secretions has been suggested, however, it has proved very difficult to grow the organism from areas outside the stomach. A nested polymerase chain reaction (N-PCR) for the specific detection of H. pylori was developed with two primer pairs (nested primers) derived from the urease gene A of H. pylori. The N-PCR could detect all 21 H. pylori strains, including 20 isolated strains and 1 reference strain NCTC 14126, but could not detect other bacterial species, showing the N-PCR assay to be 100% specific. Tenfold serial dilution experiments revealed the detection of as little as 0.1 fg DNA by N-PCR. To evaluate the PCR assay for clinical samples, gastric biopsy and aspirate specimens were tested by N-PCR, and the results were compared with those of culture, urease test and histologic examination (reference standard, RS). Among 57 biopsy specimens, H. pylori sequence was detected by PCR in 39 of 39 (100%) positive tissues and in none of 18 negative tissues. H-pylori was detected in saliva of 11 out of 19 cases in which H. pylori was positive in gastric mucosa by PCR. Whereas, PCR was positive in saliva of only one out of 8 cases in which H. pylori was negative in gastric mucosa. Six gastric aspirate specimens were positive by N-PCR. PCR is an accurate and sensitive method that can detect the presence of H. pylori without the need of culture.

Role of thyroid hormone in the expression of apolipoprotein A-IV and C-III genes in rat liver

The genes coding for apolipoproteins A-I, C-III, and A-IV are closely linked to one another in the rat genome. Thyroid hormone stimulates apoA-I expression in rat liver by an unusual mechanism that enhances the maturation of mRNA. This hormone also increases apoA-IV mRNA abundance by a mechanism not yet studied, and its role in the expression of apoC-III has not been defined but may be of relevance to the metabolism of triglyceride-rich lipoproteins. We therefore measured the transcriptional activity of the apoA-IV and apoC-III genes and the abundance of their nuclear RNA and total cellular mRNA in livers of control rats and rats made hyper- and hypothyroid. After a single receptor-saturating dose of triiodothyronine (3 mg/100 g body weight), apoA-IV gene transcription increased at 20 min and reached a maximum of 260% of control at 6 h. Increases of transcription were reflected in increases of nuclear and total apoA-IV mRNA levels. ApoC-III gene transcription was temporarily increased to 160% at 2 h without changes in the abundance of its nuclear or total mRNA over 24 h. Lower hormone doses (20-500 micrograms/100 g body weight) stimulated apoA-IV mRNA transcription as well, but tended to reduce transcription from the apoC-III gene. Upon chronic administration of thyroid hormone, apoA-IV transcription decreased to 55% and nuclear apoA-IV RNA levels to 87% of control. However, total cellular apoA-IV mRNA levels increased to 279% of control, implying stabilization of mRNA in the cytoplasm. ApoC-III transcription decreased to 28% of control, but abundance of nuclear and total cellular apoC-III mRNA was reduced to a lesser extent. In hypothyroid rats, apoA-IV gene expression was decreased fourfold at the transcriptional level. In contrast, apoC-III gene transcription increased to 178% of control, but the abundance of nuclear and total cellular apoC-III mRNA did not differ from control rats. Thus, thyroid hormone affects the abundance of apoA-IV mRNA by changing its synthesis and its rate of degradation and enhances the efficiency of apoC-III mRNA maturation, thereby blunting the net effect of altered mRNA synthesis on mRNA abundance.

Basal cell nevus syndrome and congenital hydrocephaly

A case of basal cell nevus syndrome or Gorlin's syndrome is reported in a newborn. The skin condition is associated with congenital hydrocephaly and skeletal malformations. To our knowledge, this is the first case of basal cell nevus syndrome with skin tumors present at birth and localized on the fingers.

Inhibition of Actinomyces viscosus--Porphyromonas gingivalis coadhesion by trypsin and other proteins

Protease activity is associated with the coadhesion of Actinomyces viscosus and Porphyromonas gingivalis. To try to distinguish whether the recognition/adhesion or degradative functions of proteases are more crucial for coadhesion, we determined the effect of trypsin and other purchased proteases and proteins on coadhesion when they were incorporated in the coadhesion assay buffer or when A. viscosus cells were pretreated with trypsin. Coadhesion was measured by the decrease in turbidity caused by the absorption of A. viscosus cells from aqueous suspension by P. gingivalis-coated hexadecane droplets. Pretreatment of A. viscosus with trypsin had no obvious effect on the kinetics of coadhesion. Likewise, trypsinization of A. viscosus failed to aid or enhance coaggregation by chemically induced, trypsin activity-deficient mutants of B. gingivalis. In contrast, incorporating trypsin in the buffer during the coadhesion assay yielded a concentration-dependent inhibition of coadhesion greater than the inhibition found with the same concentration of other proteases. Coadhesion was also impaired to a greater extent by similar wt/vol concentrations of nonproteolytic proteins (bovine serum albumin (BSA), defatted BSA, gelatin, and casein), by antisera against whole P. gingivalis cells and fimbriae, by preimmune serum, and by the amino acid arginine but not lysine. These findings suggest that the role of proteases in coadhesion is not solely to enzymatically "prime" A. viscosus for more avid coadhesion and that their role as potential protein or peptide seeking adhesins should be considered.

Treponema denticola induces actin rearrangement and detachment of human gingival fibroblasts

Spirochetes are associated with destructive periodontal diseases, and one cultivatable oral species, Treponema denticola, binds to mammalian cells and perturbs metabolism. To evaluate the cytoskeletal responses and attachment functions of human gingival fibroblasts (HGF) exposed to T. denticola, monolayers of HGF were incubated with T. denticola strains ATCC 35405, e, and e' in serum-free medium. HGF retracted pseudopods, rounded up, and ultimately detached from the substratum. Scanning electron microscopy showed spirochetes in close contact with HGF surfaces; occasionally, bacteria were partially submerged between folds in the HGF membrane. Blebbing and numerous microvilli formed on the cell surface as the HGF retracted. By confocal microscopy, spirochetes were detected in contact with the HGF surface but were never found on the ventral surface of fibroblasts between the substratum and cell. Morphological alterations were associated with and preceded by actin assembly, as measured by microscopic fluorimetry: there was a 263% increase in actin fluorescence over controls within 30 min. Detachment of fibroblasts from the substratum was related to incubation time and was dependent on the concentration of T. denticola. Detachment was observed for all strains tested and was also dependent on the viability of T. denticola: UV light, heat, and metronidazole treatment markedly reduced the HGF detachment response. Detachment was also significantly reduced by the protease inhibitor phenylmethylsulfonyl fluoride. HGF viability was not significantly affected by coincubation with spirochetes, as measured by lactate dehydrogenase release. Thus, T. denticola induces rapid cytoskeletal remodelling followed by cell detachment, which might be stimulated by a bacterially associated protease but is not likely directly mediated by proteolytic degradation at the cell-substratum adhesive contact points.

Onychomycoses due to Microascus cirrosus (syn. M. desmosporus)

Microascus cirrosus is very rarely the aetiological agent of onychomycosis. We report two additional cases of toenail infections caused by this fungus.

Review and new case reports on scanning electron microscopy of pili annulati, Monilethrix and Trichothiodystrophy

Pili annulati, Monilethrix and Trichothiodystrophy are uncommon conditions in which the hair shaft has a distinct appearance as seen by optical microscopy and scanning electron microscopy (SEM). We report several new cases and review the characteristic ultrastructural abnormalities investigated by SEM. Pili annulati: abnormal areas which show a longitudinal, "curtain-like" folding of the cuticular cells, alternating with normal areas. The latter present regularly non-systematized, superficial depressions. Hair specimens of the patient's mother show the same surface irregularities. Monilethrix: most hair shafts show variations in thickness giving a typical nodal appearance. In the isthmus area we noticed longitudinal ridging and cuticular scales that are extended lengthwise in a fish-scale-like pattern. In the nodus area a smooth surface due to a complete loss of cuticular cells, was observed. Trichothiodystrophy: the hair morphology observed by SEM is characterized by severe cuticular and secondary cortical degeneration along the entire length of the flattened hair shaft, with longitudinal ridging, cuticle loss, trichlorrhexis nodosa formation and trichoschisis. SEM observations show morphological abnormalities which are characteristic for each pathological condition described. This method may provide data that add some clarity in the surface changes of the different hair shaft anomalies.

Cutaneous lesions as a clue to severe combined immunodeficiency

A 2-month-old boy experienced cutaneous lesions that revealed an underlying severe, combined immunodeficiency (SCID). It is important to recognize cutaneous manifestations of primary immunodeficiency disorders, as they may provide the earliest clue to a defect in immune function.

Gingival crevicular fluid concentration and side effects of minocycline: a comparison of two dose regimens

The purpose of this study was to conduct a direct comparison of two dose regimens of minocycline to determine 1) whether they achieved crevicular fluid concentrations in a therapeutic range; and 2) the frequency of side effects. In a double-blind design, 30 patients divided into 2 groups were given either 100 mg minocycline or 200 mg minocycline per day for an 8-day period. The concentration of minocycline in the gingival clevicular fluid (GCF) at 8 days was 4.77 micrograms/ml for the 100 mg a day group and 5.97 micrograms/ml for the 200 mg a day group and at 15 days was 4.30 micrograms/ml for the 100 mg a day group and 4.17 micrograms/ml for the 200 mg a day group. There was no significant difference in the antibiotic concentration in the gingival crevicular fluid between the 2 groups. Reported adverse experiences to the minocycline were greater in the 200 mg a day group. Short-term changes in periodontal health as measured by plaque index, gingival index, pocket depth, and bleeding upon probing showed improvements in all parameters over the 15 day period. There were no significant differences in these parameters between the 100 mg a day and 200 mg a day group. At 8 days reduced levels of Porphyromonas gingivalis and Prevotella intermedia were achieved but they were not eliminated from infected subgingival sites in either group. Achieving bacteriostatic concentrations of GCF, fewer side effects, and the potential for better compliance suggests that a single daily dose of 100 mg minocycline should now be investigated for its efficacy in managing periodontal infections manifesting as periodontitis.

[The effect of neutral fraction of cigarette smoke condensate on DNA content of hamster's tracheal epithelial cells]

Histologic changes and DNA content alterations of hamster's tracheal epithelial cells induced by Benzo(a)pyrene[B(a)P] and/or the neutral fraction of cigarette smoke condensate (CSC-NF) in organ culture were investigated by light microscopy and automated image analysis technique. The results showed that B(a)P + CSC-NF induced severe atypical hyperplasia of the epithelium. Additionally, the DNA content and the percentage of cells with aneuploid DNA content also increased significantly. The histogram of DNA distribution became apparently widened. The high peak was shifted to the right and many irregular median and low peaks were also obtained.

[Factors predicting development of decubitus ulcers among patients admitted for neurological problems]

In this prospective study, factors contributing to the development of decubitus ulcers were examined. Factors were identified by a literature review and a conceptual framework was developed. Regular observations were made during the subjects' hospitalization to determine the incidence of decubitus ulcers, and to assess other decubitus ulcer risk factors. Seventeen out of 146 admitted for neurological problems patients developed decubitus ulcers during the three month study period. There were no significant differences in the level of serum albumin, hemoglobin or age between those who developed decubitus ulcers and those who did not. There also was no difference in incidence between patient who were paralyzed and those not paralyzed. Mean hospitalization days until decubitus ulcer development was 6.5 days. According to the results of discriminant analysis, four factors--1) friction and shear, 2) sensory perceptual impairment, 3) low diastolic pressure, and 4) multiple use of sedative medications--predicted 84.93% of decubitus ulcer incidence.

Trichothiodystrophy, mental retardation, short stature, ataxia, and gonadal dysfunction in three Moroccan siblings

Three sibs, a boy and two girls, born to Moroccan consanguineous parents, were affected with a syndrome characterized by brittle hair, mental retardation, short stature, ataxia, and gonadal dysfunction. The hair in these three patients displayed the morphological and biochemical hallmarks of trichothiodystrophy (TTD). Gonadal function tests showed abnormal gonadotropic responses to LHRH, consistent with delayed puberty in the male and ovarian failure in both females. Comparison with previously reported cases of TTD associated with mental retardation suggests genetic heterogeneity, although specific biochemical markers are needed in order to answer this question.

Studies of human platelet ultrastructure and quantitative analyses of membrane glycoprotein IIB/IIIA in shear stress-induced platelet quick release reaction

The ultrastructural characteristics of platelets and the quantitative analysis of membrane glycoprotein (GP) IIb/IIIa quick-release reaction induced by high shear stress (HSS) were studied with transmission electron microscope and immunocolloidal gold staining. The results showed that platelets were activated and aggregated by HSS (50 dynes/cm2 or 100 dynes/cm2). Besides, HSS also caused a special platelet quick-release reaction which was called granule-membrane-fused lytic release (GFLR). GFLR differed from releases I and II which were induced by ADP and thrombin respectively. Granules were released quickly and lysis occurred when all granules had been discharged in GFLR. GFLR is a special form of platelet quick release induced by HSS and is called release III by the authors. In the process of platelet activation and lysis, the gold particles of GPIIb/IIIa were increasingly condensed. The possible reasons of increased surface expression of GPIIb/IIIa stimulated by HSS are also discussed.

[A quantitative study of human platelet membrane glycoproteins using immunocolloidal gold under the electron microscope]

Two human platelet membrane glucoproteins (GP) and the quantitative changes of them induced by high shear stress (HSS) were studied using SZ-2 and SZ-21 monoclonal antibodies against GPIb and GPIIb/IIIa respectively by means of immunocolloidal gold technique with electron microscopy. Exposure to HSS (50 dynes/cm2, 5 min; 100 dynes/cm2, 3 min) resulted in the transformation of platelets from native smooth discs to activated spiny spheres followed by the centralization of organelles and lysis or aggregation of platelets. The results showed that resting platelets with few gold probes were turned into activated platelets by HSS with increased gold probes which represent the quantity of GPIb or GPIIb/IIIa. HSS also caused a specific platelet reaction--lysis. In the process of platelet lysis, platelet GPIIb/IIIa were increasingly condensed. On the contrary, GPIb reduced gradually. It suggests that the increase of GPIIb/IIIa under HSS may be one of the causes inducing platelet adhesion, release and aggregation at the opening of branched vessels, curved arteries, stenosed or partially occluded arteries due to local spasm.