Human pallial MGE-type GABAergic interneuron cell therapy for chronic focal epilepsy

Mesial temporal lobe epilepsy (MTLE) is the most common focal epilepsy. One-third of patients have drug-refractory seizures and are left with suboptimal therapeutic options such as brain tissue-destructive surgery. Here, we report the development and characterization of a cell therapy alternative for drug-resistant MTLE, which is derived from a human embryonic stem cell line and comprises cryopreserved, post-mitotic, medial ganglionic eminence (MGE) pallial-type GABAergic interneurons. Single-dose intrahippocampal delivery of the interneurons in a mouse model of chronic MTLE resulted in consistent mesiotemporal seizure suppression, with most animals becoming seizure-free and surviving longer. The grafted interneurons dispersed locally, functionally integrated, persisted long term, and significantly reduced dentate granule cell dispersion, a pathological hallmark of MTLE. These disease-modifying effects were dose-dependent, with a broad therapeutic range. No adverse effects were observed. These findings support an ongoing phase 1/2 clinical trial (NCT05135091) for drug-resistant MTLE.

Genetic, functional, and histopathological evaluation of two C-terminal BRCA1 missense variants

BACKGROUND

The vast majority of BRCA1 missense sequence variants remain uncharacterized for their possible effect on protein expression and function, and therefore are unclassified in terms of their pathogenicity. BRCA1 plays diverse cellular roles and it is unlikely that any single functional assay will accurately reflect the total cellular implications of missense mutations in this gene.

OBJECTIVE

To elucidate the effect of two BRCA1 variants, 5236G>C (G1706A) and 5242C>A (A1708E) on BRCA1 function, and to survey the relative usefulness of several assays to direct the characterisation of other unclassified variants in BRCA genes.

METHODS AND RESULTS

Data from a range of bioinformatic, genetic, and histopathological analyses, and in vitro functional assays indicated that the 1708E variant was associated with the disruption of different cellular functions of BRCA1. In transient transfection experiments in T47D and 293T cells, the 1708E product was mislocalised to the cytoplasm and induced centrosome amplification in 293T cells. The 1708E variant also failed to transactivate transcription of reporter constructs in mammalian transcriptional transactivation assays. In contrast, the 1706A variant displayed a phenotype comparable to wildtype BRCA1 in these assays. Consistent with functional data, tumours from 1708E carriers showed typical BRCA1 pathology, while tumour material from 1706A carriers displayed few histopathological features associated with BRCA1 related tumours.

CONCLUSIONS

A comprehensive range of genetic, bioinformatic, and functional analyses have been combined for the characterisation of BRCA1 unclassified sequence variants. Consistent with the functional analyses, the combined odds of causality calculated for the 1706A variant after multifactorial likelihood analysis (1:142) indicates a definitive classification of this variant as "benign". In contrast, functional assays of the 1708E variant indicate that it is pathogenic, possibly through subcellular mislocalisation. However, the combined odds of 262:1 in favour of causality of this variant does not meet the minimal ratio of 1000:1 for classification as pathogenic, and A1708E remains formally designated as unclassified. Our findings highlight the importance of comprehensive genetic information, together with detailed functional analysis for the definitive categorisation of unclassified sequence variants. This combination of analyses may have direct application to the characterisation of other unclassified variants in BRCA1 and BRCA2.

Human papillomavirus, smoking, and cancer

BACKGROUND

The effect of smoking on human papillomavirus (HPV) activity and subsequent dysplasia and neoplasia remains controversial.

OBJECTIVE

To determine any reported effects of smoking on either HPV activity or HPV-related dysplasia/cancer using retrospective analysis of the literature from 1966 through 1998 via Toxline and PubMed to search for "smoking," "papillomavirus," and "cancer."

CONCLUSION

Several recent large studies demonstrated that smoking was associated with a greater incidence of cervical, vulvar, penile, anal, oral, and head and neck cancer in a dose-dependent fashion, while other studies did not show any correlation between smoking and cervical dysplasia after multivariate adjustment. Recent studies have also indicated that smoking may be more closely related to high-grade lesions of the cervix and vulva. These data provide evidence of an association between HPV, smoking, and cancer. Progression of dysplasia likewise seems to be associated with smoking. Several groups have attempted to discern whether the connection between smoking and cervical cancer is from local immunosuppression and/or from direct carcinogenic effects.

Pregnancy outcome following gestational exposure to echinacea: a prospective controlled study

BACKGROUND

Echinacea products are among the most popular phytomedicines on the North American market. Since at least half of all pregnancies are unplanned, many women inadvertently use echinacea in their first trimester. Presently, there is a paucity of information regarding the gestational safety of this herb. The primary objective of this study was to evaluate the safety of echinacea in pregnancy when used for upper respiratory tract ailments.

PATIENTS AND METHODS

The study group consisted of women who were prospectively followed up after contacting the Motherisk Program regarding the gestational use of echinacea. This cohort was disease-matched to women exposed to nonteratogenic agents by maternal age, alcohol, and cigarette use. Rates of major and minor malformations between the groups were compared.

RESULTS

A total of 206 women were enrolled in the study group after using echinacea products during pregnancy; 112 women used the herb in the first trimester. There were a total of 195 live births, including 3 sets of twins, 13 spontaneous abortions, and 1 therapeutic abortion. Six major malformations were reported, including 1 chromosomal abnormality, and 4 of these malformations occurred with echinacea exposure in the first trimester. In the control group, there were 206 women with 198 live births, 7 spontaneous abortions, and 1 therapeutic abortion. Seven major malformations were reported. There were no statistical differences between the study and control groups for any of the end points analyzed.

CONCLUSIONS

This first prospective study suggests that gestational use of echinacea during organogenesis is not associated with an increased risk for major malformations.

Genetic polymorphism and their contribution to cancer susceptibility

Since the majority of chemical carcinogens are not capable of causing hazardous effects per se, the metabolism of these compounds is a crucial part of the initial host response to the environmental exposure. Disturbances in the balance between activation and detoxification may thus explain the individual variations in responses to exposures to carcinogens. The amount of the ultimate carcinogen produced depends on the action of competing activation and detoxification pathways involving cytochrome P450 and glutathione-S-transferases enzymes.

Suppression of malignant phenotype of a transformed mouse mammary epithelial cell line (11A1) by tumor suppressor gene RB

A malignant transformed mammary epithelial cell line (11A1) was transfected with liposome encapsulated eukaryotic expression plasmid pCMV-neo-RB, yielding 4 constant clones which have obvious phenotypic reversion changes, and named 11A1-R1-R4 respectively. Further experiments showed that the 11A1-R1 behaved like normal epithelial cells in both morphological and biological characteristics, with decreased clonogenicity in solid argar medium as well as decreased tumorigenicity. Northern blot hybridization showed increased expression of RB gene and decreased expression of c-myc gene in 11A1-R1, 11A1-R2 cells compared to 11A1 cells. This was an ideal phenotypic reversion model for epithelial transformed cell line and demonstrated that the RB gene can reexpress and suppress malignant phenotype in RB inactive cells.

Restriction endonuclease analysis of nosocomial isolates of Clostridium difficile

A total of 110 clinical isolates of Clostridium difficile were analyzed by agarose gel electrophoresis by using both bacterial restriction endonuclease analysis (REA) and plasmid profiles. A total of 72 isolates were divided into 12 groups according to their REA patterns. Some 38 isolates exhibited unique patterns. Pattern A occurred in 20% of isolates. Isolates with patterns B, E, and G were cytotoxin negative. The remaining groups were cytotoxin positive. Multiple isolates obtained from two stool specimens were studied to examine the variation in REA profiles found in single specimens. In these specimens no variation in REA profiles was found. The stability of C. difficile was studied by examining sequential in vitro subcultures of a single isolate and strains isolated over a 4-month period from two long-term carriers. REA patterns were stable over time, both in vitro and in vivo. Because plasmid DNA was observed in 53% of isolates, plasmid profiles alone could not be used to study the spread of C. difficile; however, they were necessary for the interpretation of REA patterns in some instances.

SCE and UDS studies in a family with retinoblastoma: a case study

The frequencies of both spontaneous and mitomycin C (MMC)-induced sister chromatid exchanges (SCE) were analyzed in mixed lymphocyte cultures from a kindred with retinoblastoma. Both the affected daughter and male proband, as well as two normal controls, were studied. No differences were observed in the spontaneous or in the MMC-induced SCE frequencies obtained from the peripheral lymphocytes of these patients compared to the normal controls. Unscheduled DNA synthesis (UDS) was observed in the lymphocytes treated with varying concentrations of both MMC and M-methyl-N-nitro-N-nitrosoguanidine (MNNG). Whereas no differences were observed in the rate of [3H]thymidine incorporation in the retinoblastoma-derived lymphocytes exposed to MMC when compared to the controls, differences were seen in the response to MNNG. Our data suggest that cells from these retinoblastoma patients respond like normal cells to damage induced by MMC, but that they are unable to repair damage induced by MNNG.

Mammalian in vivo and in vitro cytogenetic assays: a report of the U.S. EPA's gene-tox program

This report presents an assessment made by the U.S. Environmental Protection Agency Gene-Tox Program's Work Group on mammalian cytogenetics of the clastogenic effects of chemicals in in vivo and in vitro mammalian cell assays. This assessment is based on information provided by the Environmental Mutagen Information Center, Oak Ridge National Laboratory, with the proviso that the experimental protocol used in these papers was adjudged to be acceptable by standards outlined by the Work Group. Some data were accepted as "qualitative only" because the protocol used was fairly close to that proposed as suitable. Using these criteria, 177 papers were selected for review. 6 assays were reviewed: bone marrow (32 papers, 31 chemicals), spermatogonial (10 papers, 10 chemicals), spermatocyte (25 papers, 25 chemicals), oocyte or early embryo (18 papers, 19 chemicals), in vitro cell culture (30 papers, 66 chemicals), and leukocyte (66 papers, 53 chemicals). Each assay was considered separately, and comparisons were then made between them for their similarities or differences in producing a positive or negative clastogenic effect of a particular chemical or chemical class. A large proportion of the available cytogenetic data was not suitable for inclusion in the final data base because of poor experimental design or unsatisfactory reporting of the information. It was not possible to recommend any one assay for determining potential clastogenicity because each had its own particular advantages and limitations and provided unique information. For demonstrating in vivo effects, the bone-marrow assay is probably the simplest and most economical. If only in vitro exposures were considered, leukocytes or cultured mammalian cell lines would be suitable. However, there are advantages to using leukocytes because they are a synchronous population, at least through their cell division, and because of the ready availability of human cells. In general, there was good agreement between clastogenicity and carcinogenicity.

Cytogenetic toxicity of cyclophosphamide and its metabolites in vitro

The effects of cyclophosphamide and three of its known metabolites (nitrogen mustard, acrolein, and nor-nitrogen mustard on chromosome breakage and sister chromatid exchange (SCE) were analyzed in vitro with and without the presence of a metabolic activating system (liver S9). We confirmed that cyclophosphamide induced chromosome breakage and SCE only in the presence of S9. After metabolism, cyclophosphamde was more active than the other agents in inducing SCE. Thus, the agent(s) directly responsible for this induction of a high SCE rate was not analyzed in this study. On the other hand, acrolein was most toxic to cell proliferation and most active in inducing chromosome breakage. The cytogenetic toxicity of these agents in comparison with their mutagenic and therapeutic activities is discussed.

Cytochemical analysis on a case of familial 17ps

Chromosome 17ps was identified in the mother and daughter but not the father of a normal family with no history of congenital abnormality. In addition to G-band and Ag-NOR staining, previously used to study this abnormality, we applied N-band and C-band techniques. Our results showed that 17ps has no demonstrable ribosomal cistron or constitutive heterochromatin.

Further study of the genetic toxicity of gentian violet

The genetic toxicity of gentian violet was studied with the Ames and the Rosenkranz bacterial assays as well as the cytogenetic assays (Chinese hamster ovary cells in vitro in the presence of rat-liver S-9 fractions, the chicken-embryo and mouse-bone-marrow cells in vivo). Gentian violet was found to be toxic but not mutagenic in the Ames assay. However, it was active in the Rosenkranz assay causing reparable DNA damage. The presence of S-9 in the in vitro cytogenetic assay and in the bacterial assays showed that the activity of gentian violet could be reduced or eliminated. In the in vivo assays, gentian violet was not clastogenic and failed to induce sister-chromatid exchanges. However, gentian violet proved to be highly toxic to growing chick embryos at high dosage and depressed mitotic activities in mouse bone marrow after prolonged treatment. Our study suggested that gentian violet can be inactivated by the liver detoxification system. However, it is potentially hazardous to cells that are exposed to the dye directly (e.g. skin epithelium and cell lining of the gastrointestinal tract).

Studies on the clastogenic effects of biologic stains and dyes

We have surveyed the clastogenic potential of 12 different groups of stains and dyes totalling 48 compounds. We observed that 18 compounds induced significant increase in chromosome damage. Most of them were also found to be mutagenic, carcinogenic, or toxic in other reported studies. However, no significant studies were reported on six of them. It is concluded that these agents are potentially harzardous and should be studied further in detail.

Cytogenetic toxicity of gentian violet and crystal violet on mammalian cells in vitro

The cytogenetic toxicity of gentian violet in Chinese hamster CHO cells in vitro has been studied by analyzing (1) squash preparations from direct fixation for recording mitotic anomalies and (2) air-dried preparations (with colcemid--hypotonic pretreatments) for recording metaphase chromosome aberrations. It was concluded that this compound is a mitotic poison as well as a clastogen in vitro. Its clastogenic property was confirmed in 5 other different mammalian cel types. 10 samples of different gentian violet and crystal violet were surveyed and all were shown to be clastogenic. Unless in vivo studies prove otherwise, gentian violet and crystal violet should be regarded as biohazardous substances.

Excess chromosome no. 4 in ethylnitrosourea-induced neurogenic tumor lines of the rat

The chromosomes in 15 cell lines derived from separate tumors induced in rats by ethylnitrosourea (ENU) are described. Thirteen lines were neural (glioma or schwannoma) in origin and type. In 12 of these lines, excess chromosome no. 4 could be demonstrated by Giemsa banding. One to three extra no. 4 chromosomes were seen as numerical or structural abnormalities. Also noted were other changes that were not consistent among lines. The 12 lines produced tumors in newborn rats. The 13th neurogenic line lacked excess chromosome no. 4 and did not produce tumors. The remaining 2 lines were nonneurogenic and lacked excess chromosome no. 4 but produced tumors. Control studies included chromosome analyses of bone marrow preparations from ENU-treated rats with tumors, cell lines from brains of normal rat embryos, and 2 established nonneurogenic rat tumor lines. No excess chromosome no. 4 was seen. These results suggest that nondisjunction and/or rearrangement of chromosome no. 4 is associated with the oncogenic process in neurogenic tumors induced.

Establishment of a human medulloblastoma cell line

A cell line consisting of polygonal and fusiform cells was derived from a cerebellar medulloblastoma. Cells grew to high population density in liquid medium and formed colonies in agar medium. No neural or glial elements could be demonstrated in the cultured cells by electron microscopy nor were virus particles detected. The cells formed tumors in nude mice and in antithymocytic serum (ATS)-treated hamsters. The tumors had a microscopic appearance similar to that of the medulloblastoma from which the cell line was derived. The cell line and lines derived from the transplant tumors in two hosts had four common "marker" chromosomes as well as non-specific cytogenetic changes.

The effect of ethylnitrosourea on chromosome aberrations in vitro and in vivo

The effect of ENU on (A) human chromosomes from blood lymphocyte cultures in vitro, and on (B) rat and mouse bone marrow chromosomes in vivo, was investigated. Doses of 25, 50, 100 and 200 mug/ml were tested in vitro and cells with chromosome breakage were found to be dose dependent. Chromosome damage was also dependent on time; maximum damage was seen when cells were treated 2--6 hrs before harvest. Two doses of 100 and 200 mg/kg were studied in rat and mouse in vivo and a dose effect could be shown in both species. The highest number of abnormal cells was found 6 hrs after treatment; there was a sharp decrease at 18 hrs and thereafer. Types of aberrations were also analyzed, in both in vitro and in vivo studies.

Identification of the sex chromosomes in the bald eagle

Karyotypes of five American bald eagles (Haliaeetus leucocephalus and H. alacanus) are compared. All had 2n=66 chromosomes which fell into 3 size groups: A, 20 pairs of biarmed chromosomes; B, 9 pairs of acrocentric chromosomes and C, 4 pairs of microchromosomes. C-banding was done in two eagles and a heterochromatic W chromosome was identified in a presumptive female. The ZZ and ZW chromosomes could be identified in the karyotypes.