[Microscopic observation of the enamel microstructures of SD rats with different degrees of fluorosis].

Objective: To establish a dental fluorosis model of SD rats with various degrees, to observe the microstructures of enamel samples under scanning electron microscope and to clarify the changes of enamel microstructures with various degrees of dental fluorosis, so as to provide clinical reference for the treatment of patients with moderate and severe dental fluorosis. Methods: Thirty male SD rats (6 weeks of age) were randomly divided into 3 groups with 10 rats in each group. The control group was fed with deionized water without fluoride, the low fluoride group was fed with 50 mg/L NaF deionized water and the high fluoride group was fed with 100 mg/L NaF deionized water in order to establish the dental fluorosis model of rats. After feeding for 6 weeks, the rats were sacrificed and the mandibular incisor teeth were collected and recorded. The surface and sagittal plane of each tooth were observed by scanning electron microscopy and the enamel thickness was measured. Results: In the control group, the enamel color was brown yellow. Enamel color discoloration occurred both in low-fluoride group and high-fluoride group. The enamel color in low-fluoride group was mostly yellow and white striped while in high-fluoride group was mostly chalky white. Under electronic microscope, the enamel rods were alternately arranged and their structure was clear and plump in the control group. The enamel rods of moderate fluorosis were arranged in a straight orientation like tips of bamboo shoots. The enamel rods of severe fluorosis, however, became thinner and the tips of rods were broken. In the control group, sagittal images of enamel turned out to be a dense outer structure with clear boundaries among the inner. The structure of the middle layer was reticulated showing a clear boundary with middle and outer layers. The structure of enamel rods in the inner layers was arranged vertically and horizontally. In the moderate fluorosis group, the outer layer of the enamel became thinner and the middle layer disappeared although the boundary between the outer and middle layers was still clear. In the inner layer, the vertically arranged enamel rods seemed still clear, however the horizontal enamel rods disappeared. In the severe fluorosis group, the outer layer could not be traced. The middle layer was exposed to the air and the inner enamel rods contracted. The inner layers of the enamel had gradually become thinner with the development of the dental fluorosis. The thicknesses of inner layers in control, moderate and the severe groups were (180.71±7.01), (157.10±11.04) and (121.10±12.56) µm respectively. As for the thicknesses of the full layers in the above mentioned three groups, the same trend was observed. The thicknesses, in order of the severity of dental fluorosis, were (241.54±7.76), (207.42±14.36) and (143.79±14.60) µm. Conclusions: With the development of dental fluorosis, the outer enamel layers became thinner or disappeared and the inner enamel layers became thinner or lost its normal structure as well. It is highly recommended that the resin penetration could be used for the proper treatment of moderate and severe dental fluorosis and the strong bleaching and the micro-grinding should be used cautiously.

The role of posterior corneal power in 21st century biometry: A review.

PURPOSE: Intraocular lens (IOL) calculation and biometry have evolved significantly in recent decades. However, present outcomes are still suboptimal. Our objective is to summarize the results reported in the literature with regard to a new variable, the value of the relationship between anterior and posterior corneal curvature in the biometric calculation of IOL power. METHODS: We have created a narrative revision of the existing evidence regarding the posterior to anterior corneal curvature ratio in IOL calculation. RESULTS: The corneal posterior/anterior ratio (P/A ratio), also called Gullstrand ratio, has a standard deviation of 2.4% in normal people, hence causing a possible IOL power miscalculation error of up to 0.75 diopters (D). This error is magnified in pathological corneas or in those with previous refractive surgery. Including the P/A ratio in the IOL formula reduces errors in the calculation of IOL power. CONCLUSIONS: Measurement of the posterior corneal surface should be recommended prior to IOL calculation, given the demonstrated results regarding the P/A ratio for IOL power calculation. Regarding toric IOL calculation, we suggest incorporation of all internal astigmatic vectors, for instance, posterior corneal surface, IOL tilt induced toricity, and retinal astigmatism. All of these factors may improve surgical outcomes.

Extraction of an intraorbital foreign body with the help of an ocular external electromagnet: Instruments of the past still have a place in the present. / Extracción de cuerpo extraño orbitario con ayuda de electroimán ocular externo: instrumentos del pasado tienen cabida en el presente.

Intraorbital Foreign Bodies (IOFB) are objects, usually of metallic nature, located outside the orbit cavity, and can potentially cause serious damage to ocular and orbital structures. The case is presented of a patient with an anterior metallic IOFB that was extracted with the aid of a Livingston-Mansfield ocular external electromagnet. Despite being an instrument «of the past¼, we believe that the electromagnet can still be useful in certain circumstances.

HLA-A, -B and -DRB1 genotyping and haplotype frequencies of 3892 cord blood units in the Hong Kong Chinese Cord Blood Registry.

HLA-A, -B and -DRB1 gene and haplotype frequencies have been calculated from 3892 southern Chinese unrelated cord blood units in a Hong Kong Cord Blood Registry. This is the first large-scale paper to report the distribution of A-B-DRB1 alleles in Hong Kong Chinese Cord Blood Units. This information is important for estimating the optimal and economically cost-effective donor size and likelihood of obtaining appropriately matched cord blood units for Chinese patients awaiting haematopoietic stem cell transplantation. The data are available in the Allele Frequencies Net Database under the population name ''Hong Kong Chinese Cord Blood Registry'' and the identifier (AFND003358).

HLA-A, -B, -C, and -DRB1 genotyping and haplotype frequencies for a Hong Kong Chinese population of 7595 individuals.

HLA-A, -B, -C and -DRB1 gene and haplotype frequencies have been calculated from 7595 southern Chinese unrelated donors in a Hong Kong Bone Marrow Donor Registry. This is the first large-scale paper to report the distribution of A-C-B-DRB1 alleles in Hong Kong Chinese. This information is important for phylogenetic, comparative studies and estimating the optimal and cost-effective donor size and likelihood of obtaining appropriately matched donors for Chinese patients awaiting haematopoietic stem cell transplantation. The allele and haplotype data are available in the Allele Frequencies Net Database under the population name ''Hong Kong Chinese BMDR'' and the identifier (AFND003357).

Revealing of the transition from n- to p-type conduction of InN:Mg by photoconductivity effect measurement.

We report evidence of the transition from n- to p-type conduction of InN with increasing Mg dopant concentration by using photoconductivity (PC) measurement at room temperature. This transition is depicted as a conversion from negative to positive PC under above-bandgap optical excitation. The n- to p-type transition in InN:Mg is further confirmed by thermopower measurements. PC detection method is a bulk effect since the optical absorption of the surface electron accumulation is negligibly low due to its rather small thickness, and thus shows advantage to detect p-type conduction. This technique is certainly helpful to study p-type doping of InN, which is still a subject of discussions.

Altered expression of hepatic metabolic enzyme and apoptosis-related gene transcripts in human hepatocytes treated with trichloroethylene.

Trichloroethylene (TCE) is a common organic solvent that has been widely used in industrial applications. Hundred cases of allergic reactions occurred after the workers were occupationally exposed to TCE in China in the past decade, but the underlying effector mechanisms of TCE remain unclear. The purpose of the present study is to examine the alteration of hepatic metabolic enzyme gene and apoptosis-related gene messenger RNA (mRNA) expression in L02 human hepatocytes (L02 cells) after treatment with TCE. L02 cells were cultured either with various doses of TCE (0.25, 0.5, 1.0 and 2.0 mmol/L) for 24 h or with a single dose of TCE (1.0 mmol/L) for different time intervals, whereas samples treated with dimethyl sulfoxide served as control. Quantitative real-time polymerase chain reaction analysis was performed to detect the mRNA expression of hepatic metabolic enzyme genes (CYP1A2, CYP3A4 and CYP2E1) and apoptosis-related genes (BAX and BAD). It was found that the transcript levels of hepatic metabolic enzyme genes and apoptosis genes including BAX and BAD were significantly increased after TCE treatment at various doses for 24 h when compared with controls. Additionally, when the cells were treated with a single dose of TCE (1.0 mmol/L) for different periods of time (3, 6, 12 and 24 h), the mRNA expression of these genes also increased significantly compared with control (p < 0.05 or p < 0.01). The conclusion of the study is that TCE could induce alteration of mRNA expression of hepatic metabolic enzyme genes and apoptosis genes, which might be implicated in the effector mechanisms of TCE cytotoxicity in vivo.

Abnormality of bone marrow-derived mesenchymal stem cells in patients with systemic lupus erythematosus.

Bone marrow-derived mesenchymal stem cells (MSCs) are key components of the hematopoietic microenvironment and provide support to hematopoiesis and modulate immune system. Several studies suggest that SLE may be seen as stem cell disorders. However, it is unclear that whether MSCs from SLE patients are defective. So in this research, we studied the biological character of bone marrow derived MSCs in patients with SLE, focused on their phenotype (morphology and immunophenotype), karyotype, cytokines expression and hematopoietic support of MSCs. Our results showed that MSCs from SLE patients and normal controls can be successfully culture-expanded, but the MSCs from SLE grew more slowly than those of normal controls (P < 0.05). Cells from both groups were positive for CD29, CD44 and CD105, and negative for CD14, CD34, CD45 and HLA-DR. MSCs from SLE have a normal karyotype. Both groups express IL-6, IL7, IL-11, macrophage colony stimulating factor (M-CSF) and stem cell factor (SCF) at mRNA level. While IL-6 and IL-7 were down-regulated in MSCs from SLE patient (P < 0.05) at mRNA level. The MSCs from SLE patients and normal controls were infused into ICR (Tac: Icr: Ha strain) mice after high-dose chemotherapy, with no adverse events in either group. Recovery of white blood cells, hemoglobin and platelet was more rapid (P < 0.05) compared with the group without MSCs infusion. We conclude that MSCs in patient with SLE have abnormalities compared with those in normal control. MSCs in patient with SLE may play an important role in the SLE pathogenesis.

Sjögren,'s syndrome and benign hyperglobulinemic purpura of Waldenstrom.

This article describes the relationship between Sjögren's syndrome and benign hyperglobulinemic purpura of Waldenstrom (BHPW). A case is reported, and evidence is shown that they are the same disease differing only in some prominent clinical manifestations.

Pseudotumor cerebri: an observation and review.

In five consecutive cases of pseudotumor cerebri we observed an elevation in the erythrocyte sedimentation rate that we were able to correlate with the changes in the degree of papilledema. In spite of an extensive medical workup, no other cause for the increased ESR was found. Our findings suggest that possibly serial ESR determinations might be of assistance in following cases of pseudotumor cerebri.

Eales' disease: a case of rapid progression.

A case of bilateral vitreous hemorrhage is presented in a young black man. Work-up showed the patient to have Hb AA with a markedly positive PPD and a negative chest roentgenogram. A diagnosis of periphlebitis retinae or so-called Eales' disease was made. This case was remarkable in its speed of progression and the severity of the disease process. This case calls attention to the importance of rapid diagnosis and evaluation for possible treatment.

Primary congenital eversion of the upper lids.

A case of bilateral primary congenital eversion of lids in a newborn black male is described. It is a self-limiting disease and does not leave any sequelae. A higher incidence in black infants has been noted in the literature.

Effects of 5-fluorouridine on modified nucleosides in mouse liver transfer RNA.

Administration of the pyrimidine antimetabolite, 5-fluorouridine, to mice was found to cause a marked specific reduction of the amounts of 5-methyluridine, pseudouridine, and dihydrouridine but not of 3-(3-amino-3-carboxypropyl)uridine in tRNA from the livers of the treated animals. The data presented indicate that this effect is not simply due to the incorporation of 5-fluorouridine into tRNA; the drug appears to interfere directly with the enzymic reactions involved in the modification of the 5-position of uridine. 5-Fluorouridine was found to have no effect on the modification of adenosine, guanosine, and cytidine in mouse liver tRNA.

Effects of DL-ethionine on mouse liver tRNA base composition.

Treatment of mice with DL-ethionine and adenine causes a reduction of all methylated bases of liver tRNA. This effect is dose-dependent and specific for the methylated bases. Individual methylated components are affected to different extents, m22G being most sensitive to inhibition.