Importance of Survey Demographic Questions to Foster Inclusion in Medicine and Research and Reduce Health Inequities for LGBTQIA2S+ Individuals

A clear, inclusive, and accurate approach to the collection of demographic information in clinical research and medical practice is critical to understanding the healthcare needs of the specific population. Inclusive demography constitutes appropriate and accurate characterization of an individual's sexual orientation and gender identity (SOGI) data. Appropriate demography fosters sense of inclusion and belonging for those belonging to medically marginalized communities such as the lesbian, gay, bisexual, transgender, queer, intersex, asexual, and Indigenous Two-Spirit (LGBTQIA2S+) communities and improves health outcomes. Acquiring inclusive demographics in healthcare research is needed for the following critical reasons. Firstly, LGBTQIA2S+ individuals experience undue psychological harm when their identities are not appropriately captured in survey data, promoting further alienation of the LGBTQIA2S+ community in medicine and research. Secondly, LGBTQIA2S+ populations are disproportionately burdened by several major cardiovascular and cardiovascular-associated diseases, including hypertension and diabetes. Failure to include these populations, and accurately characterize their participation, in research leads to failure to identify associations between identities and disease, resulting in worse health outcomes. Further, this lack of precision in current data for sex, gender, and sexual orientation may lead to inaccurate data for all populations, not just the LGBTQIA2S+ community. Lastly, there are currently major political and social threats and attacks on the LGBTQIA2S+ community and, in particular, on transgender and gender diverse individuals. Proper medical inclusion and advocacy for the LGBTQIA2S+ community by the medical community may help protect the community from further undue harm through creating sense of belonging and reductions in marginalization-related health inequities.

Novel DNA methylation signatures of tobacco smoking with trans-ethnic effects

BACKGROUND

Smoking remains one of the leading preventable causes of death. Smoking leaves a strong signature on the blood methylome as shown in multiple studies using the Infinium HumanMethylation450 BeadChip. Here, we explore novel blood methylation smoking signals on the Illumina MethylationEPIC BeadChip (EPIC) array, which also targets novel CpG-sites in enhancers.

METHOD

A smoking-methylation meta-analysis was carried out using EPIC DNA methylation profiles in 1407 blood samples from four UK population-based cohorts, including the MRC National Survey for Health and Development (NSHD) or 1946 British birth cohort, the National Child Development Study (NCDS) or 1958 birth cohort, the 1970 British Cohort Study (BCS70), and the TwinsUK cohort (TwinsUK). The overall discovery sample included 269 current, 497 former, and 643 never smokers. Replication was pursued in 3425 trans-ethnic samples, including 2325 American Indian individuals participating in the Strong Heart Study (SHS) in 1989-1991 and 1100 African-American participants in the Genetic Epidemiology Network of Arteriopathy Study (GENOA).

RESULTS

Altogether 952 CpG-sites in 500 genes were differentially methylated between smokers and never smokers after Bonferroni correction. There were 526 novel smoking-associated CpG-sites only profiled by the EPIC array, of which 486 (92%) replicated in a meta-analysis of the American Indian and African-American samples. Novel CpG sites mapped both to genes containing previously identified smoking-methylation signals and to 80 novel genes not previously linked to smoking, with the strongest novel signal in SLAMF7. Comparison of former versus never smokers identified that 37 of these sites were persistently differentially methylated after cessation, where 16 represented novel signals only profiled by the EPIC array. We observed a depletion of smoking-associated signals in CpG islands and an enrichment in enhancer regions, consistent with previous results.

CONCLUSION

This study identified novel smoking-associated signals as possible biomarkers of exposure to smoking and may help improve our understanding of smoking-related disease risk.

[Care Provided to Psychopaths in Rostock]

In the first decades of the 20^th century stations for observing "psychopathological" children and adolescents were established at a number of psychiatric facilities in the German Reich. Often they functioned as the nucleus for future psychiatric clinics for children and adolescents. Using primary sources of the Landeshauptarchiv Schwerin (main land archive in Schwerin), the local development of the neuropsychiatric clinic in Rostock-Gehlsheim is illustrated in this paper, exploring the question to what degree it caused the specific development of psychiatry in the child and adolescent age group.

[University professors in the Soviet Occupation Zone and the German Democratic Republic up to 1961: Academic alternation of generations at university psychiatric hospitals]

After WWII a politically guided staffing policy foresaw an exchange program for professors from the Soviet Occupation Zone and the German Democratic Republic (GDR). In the field of medicine this initiative was not successful. With respect to university psychiatric/neurological hospitals this experiment failed as a result of a shortage of personnel due to the consequences of war, denazification and people migrating into western occupation zones. Criteria for politically selecting promising young talent which had been propagated by the Socialist Unity Party of Germany (Sozialistische Einheitspartei Deutschlands, SED) were thus not relevant in academic medicine until 1961; however, the communist rulers had great interest in bringing professional and academic resources up to date. Politically implicated representatives in the field were also included in this process. At the forefront was the interest in functioning medical care and education in order to be able to train much needed health professionals. At the end of the 1950s a new generation of professors was established at the university hospitals. This generation rotation demonstrated the politically intended replacement of the "old" professor generation and the transition to a new GDR generation that had been trained after 1945. This second generation of professors inherited vacant professorships and defined and shaped research and academia until the end of the GDR much more than the previous generation had and also more than the one that followed. The generation of professors continued to feel a strong affiliation with their academic teachers and consequently continued their tradition in the sense of a school, for the most part independent of political circumstances.

Brain-derived neurotrophic factor in human subjects with function-altering melanocortin-4 receptor variants

Background

In rodents, hypothalamic brain-derived neurotrophic factor (BDNF) expression appears to be regulated by melanocortin-4 receptor (MC4R) activity. The impact of MC4R genetic variation on circulating BDNF in humans is unknown.

Objective

To compare BDNF concentrations of subjects with loss-of-function (LOF) and gain-of-function (GOF) MC4R variants to those of controls with common sequence MC4R.

Methods

Circulating BDNF was measured in two cohorts with known MC4R sequence: 148 subjects of Pima Indian heritage ([mean±SD]: age 15.7±6.5y, BMI-Z 1.63±1.03), and 69 subjects of Hispanic heritage (10.8±3.6y, BMI-Z 1.57±1.07). MC4R variants were characterized in vitro by cell surface expression, receptor binding, and cAMP response after agonist administration. BDNF single nucleotide polymorphisms (SNPs) rs12291186, rs6265, and rs7124442 were also genotyped.

Results

In the Pima cohort, no significant differences in serum BDNF was observed for 43 LOF-subjects versus 65 LOF-matched controls [age-, sex-, and BMI-matched] (P=0.29), or 20 GOF-subjects versus 20 GOF-matched controls (P=0.40). Serum BDNF was significantly associated with genotype for BDNF rs12291186 (P=0.006) and rs6265 (P=0.009), but not rs7124442 (P=0.99); BDNF SNPs did not interact with MC4R status to predict serum BDNF. In the Hispanic cohort, plasma BDNF was not significantly different among 21 LOF-subjects, 20 GOF-subjects, and 28 controls (P=0.79); plasma BDNF was not predicted by BDNF genotype or BDNF-x-MC4R genotype interaction.

Conclusions

Circulating BDNF concentrations were not significantly associated with MC4R functional status, suggesting that peripheral BDNF does not directly reflect hypothalamic BDNF secretion and/or that MC4R signaling is not a significant regulator of the bulk of BDNF expression in humans.

Epidemiology and genetic determinants of progressive deterioration of glycaemia in American Indians: the Strong Heart Family Study

AIMS/HYPOTHESIS

Type 2 diabetes is a chronic, heterogeneous disease and a major risk factor for cardiovascular diseases. The underlying mechanisms leading to progression to type 2 diabetes are not fully understood and genetic tools may help to identify important pathways of glycaemic deterioration.

METHODS

Using prospective data on American Indians from the Strong Heart Family Study, we identified 373 individuals defined as progressors (diabetes incident cases), 566 individuals with transitory impaired fasting glucose (IFG) and 1,011 controls (normal fasting glycaemia at all visits). We estimated the heritability (h(2)) of the traits and the evidence for association with 16 known variants identified in type 2 diabetes genome-wide association studies.

RESULTS

We noted high h(2) for diabetes progression (h(2) = 0.65 ± 0.16, p = 2.7 × 10(-6)) but little contribution of genetic factors to transitory IFG (h(2) = 0.09 ± 0.10, p = 0.19) for models adjusted for multiple risk factors. At least three variants (in WFS1, TSPAN8 and THADA) were nominally associated with diabetes progression in age- and sex-adjusted analyses with estimates showing the same direction of effects as reported in the discovery European ancestry studies.

CONCLUSIONS/INTERPRETATION

Our findings do not exclude these loci for diabetes susceptibility in American Indians and suggest phenotypic heterogeneity of the IFG trait, which may have implications for genetic studies when diagnosis is based on a single time-point measure.

[Disciplinary differentiation under socialist conditions--the establishment of neurology at the University of Rostock in East Germany]

The move towards disciplinary independence in Germany turned out to be more troublesome than in France or Great Britain and real institutional independence was not established at German universities until the 1970s of the 20th century, and this in the Federal Republic of Germany only. In East Germany (German Democratic Republic--GDR), a division into Chairs of Psychiatry and Neurology took place at individual universities and medical colleges only. Nevertheless, in exceptional circumstances, neurology did gain academic autonomy in the GDR. One such exception was the University of Rostock, where as early as 1958, the Chair of Psychiatry had been divided into three independent Chairs of Psychiatry, Neurology and Child Psychiatry. Besides internal scientific factors, socio-political constraints played a particular role here and had an influence on the disciplinary differentiation.

Genome-wide linkage scan for plasma high density lipoprotein cholesterol, apolipoprotein A-1 and triglyceride variation among American Indian populations: the Strong Heart Family Study

BACKGROUND

Recent studies have identified chromosomal regions linked to variation in high density lipoprotein cholesterol (HDL-C), apolipoprotein A-1 (apo A-1) and triglyceride (TG), although results have been inconsistent and previous studies of American Indian populations are limited.

OBJECTIVE

In an attempt to localise quantitative trait loci (QTLs) influencing HDL-C, apo A-1 and TG, we conducted genome-wide linkage scans of subjects of the Strong Heart Family Study.

METHODS

We implemented analyses in 3484 men and women aged 18 years or older, at three study centres.

RESULTS

With adjustment for age, sex and centre, we detected a QTL influencing both HDL-C (logarithm of odds (LOD) = 4.4, genome-wide p = 0.001) and apo A-1 (LOD = 3.2, genome-wide p = 0.020) nearest marker D6S289 at 6p23 in the Arizona sample. Another QTL influencing apo A-1 was found nearest marker D9S287 at 9q22.2 (LOD = 3.0, genome-wide p = 0.033) in the North and South Dakotas. We detected a QTL influencing TG nearest marker D15S153 at 15q22.31 (LOD = 4.5 in the overall sample and LOD = 3.8 in the Dakotas sample, genome-wide p = 0.0044) and when additionally adjusted for waist, current smoking, current alcohol, current oestrogen, lipid treatment, impaired fasting glucose, and diabetes, nearest marker D10S217 at 10q26.2 (LOD = 3.7, genome-wide p = 0.0058) in the Arizona population.

CONCLUSIONS

The replication of QTLs in regions of the genome that harbour well known candidate genes suggest that chromosomes 6p, 9q and 15q warrant further investigation with fine mapping for causative polymorphisms in American Indians.

[Franz Günther von Stockert between politics and science--a study in the history of the neurology and psychiatry in the GDR]

1945 marked the beginning of the so-called anti-fascist democratic transformation in the Soviet occupied zone and later GDR, which also included radical reforms in the higher education system. The aim of these reforms was to establish a "new intelligence" that was to spread Marxist-Leninist teaching in universities and colleges. However, in practice the new rulers had to rely on the old "erudite elite" which led to considerable problems. Against this socio-political background this study analyses the affairs at the neuropsychiatric clinic Gehlsheim at Rostock University, in particular those around Franz Günther von Stockert (1899-1967), who was head of the department between 1954 and 1958. Archival sources, not accessible till now, shed light on the background and motives that finally led to his dismissal and short-term imprisonment, and the consequences for the clinic. The analysis of this example also shows how external factors can influence science and the disciplinary differentiation. This case from the field of psychiatry and neurology is a contribution to the broader history of science in the GDR until 1961.

[Autism: exploring historical psychiatric and psychological concepts]

Autism today is a widely used term, yet what is understood by autism has changed considerably since first being introduced in scientific discourse almost 100 years ago. Autism is one example for the influence of the psychoanalytic school of Sigmund Freud on scientific psychiatry at the beginning of the 20th century. In particular psychoanalysis had an impact on Eugen Bleuler's concept of schizophrenia. The Swiss psychiatrist did not only acknowledge and follow a biological, but also a psychological approach to psychiatry and thus opened up his subject to psychoanalytic thoughts. This paper provides insights into the term's conceptual history--or, more specifically and precisely--sheds light on the expansion of the term's scope, which has gotten to be used for more and more symptoms and phenomena. When Bleuler first presented the term autism, he used it to refer to a classical schizophrenic symptom. Since, however, Bleuler was not very specific and exclusive in his definition, the term was soon used for other phenomena as well, such as to describe a schizoid symptom in the sense of today's schizoid personality disorder (schizoid autism). The concepts of autistic hebephrenia and depressive autism are further examples how the term was used and give insight into how the contents behind the term changed, got less and less specific and widened its scope. Due to its growing vagueness its suitability and usability as a psychopathological term decreased. This process further was strengthened when the word autism got more and more widely used in colloquial language for different aspects of day-to-day routine and thinking. Thus in psychiatry today, autism is exclusively used in connection with the so-called autism spectrum disorders, but has, as other formerly exclusively technical terms, different and rather unspecific meanings in everyday communication.

Der „Fall Sefeloge“

In 1850 the mentally disordered Sergeant Maximilian Joseph Sefeloge (1821-1859) tried to assassinate the Prussian King Friedrich Wilhelm IV (1795-1861). Besides clarification of the political background to the assassination, the question of the delinquent's criminal responsibility has been posed from the very beginning. For the first time Sefeloge's case is examined from a medicohistorical perspective. Due to the importance of the circumstances, a forensic scientist and three well-known psychiatrists made this forensic examination. These medical professionals seemed particularly competent because of their common experience with psychiatric patients. This unique case from nineteenth century Germany is exemplary in that the psychiatrist was generally accepted as an expert witness to evaluate crimes in the context of unclear mental conditions. From there the development of forensic psychiatry could proceed without hindrance.

Überlegungen zum Wirken des Neuropsychiaters Gabriel Anton (1858–1933)

Gabriel Anton (1858-1933) attained fundamental clinical neuropathological results. His scientific career and research were highly influenced by Theodor Meynert. However, in contrast to Meynert, Anton sought not only descriptions of pathological changes but also their therapy. The surgical treatment of hydrocephalus was one of his most important achievements. With this, he gave important impetus to the still new science of neurosurgery. Nowadays, Anton is still known in medical nomenclature by Anton's syndrome. The detailed description and explanation of visual anosognosia and asomatoagnosia and furthermore his emphasis on their importance can be regarded as Anton's most notable contribution to science. However, his research on basal ganglia disorders is not as well-known, although Anton's thoughts mark the beginning of further systematic research on these disorders. In addition, he did preliminary work in the development of child and adolescent psychiatry. Today, some of his work in the field of eugenics is controversial.

[Heinrich Damerow (1798-1866). Comments on the title page]

Heinrich Philipp August Damerow was one of the most important German psychiatrists of the nineteenth century. His most notable achievements were in the field of institutional psychiatry. With the construction of a clinic for the mentally ill in Halle-Nietleben, Germany, he realized the concept of a "relatively integrated Mental Hospital and Asylum." As an editor of the Allgemeine Zeitschrift für Psychiatrie und psychischgerichtlichen Medicin (Journal of Psychiatry and Psychic-Legal Medicine), he exerted considerable influence. Ideologically, Damerow was a representative until about the mid-nineteenth century of the holistic approach of medicine during the Romantic period, and he was largely influenced by the ideas of Hegel. He found justification for his service to the then ruling Prussian state in the concept of the state as manifestation of divine reason. He supported a holistic approach to treating the mentally ill in which the patient is viewed as a union of body, soul, and mind. This viewpoint was evident in his critical stance toward Esquirol's concept of monomania.

[Alfred Hauptmann - the fate of a german neurologist of jewish origin]

The pathway through life of the German psychiatrist and neurologist Alfred Hauptmann (1881 - 1948) and his work is described. It is exemplary for so many of his contemporaries of Jewish origin, who were forced to emigrate under the National Socialist dictatorship. Hauptmann's career was most of all marked by the short, but to him formative time with Max Nonne. Throughout his life his research focused on neurological topics. In 1926, Hauptmann got the chair of psychiatry at Halle University in order to continue the important neurological tradition of Eduard Hitzig, Carl Wernicke and Gabriel Anton. Until 1935, he worked as the director of the psychiatric clinic in Halle, but in the course of the Reichsbürgergesetz he had to give up his chair and his work as a doctor. The way into emigration, which was accelerated by the temporary imprisonment in the concentration camp Dachau, is described considering personal documents. After his emigration into the United States, Hauptmann was not too successful in starting new as a scientist. His most important contribution is still the article on the efficacy of Phenobarbital as an antiepileptic, which had been written already in 1912. For this reason, the Alfred-Hauptmann-Award for epilepsy research is awarded. In 1941 - after his emigration - he and Siegfried Joseph Thannhauser described the autosomal dominantly transmitted myopathy for the first time, which is today described as Hauptmann-Thannhauser myodystrophy. The name of Alfred Hauptmann should be unforgettable not only because of the entrance into medical nomenclature, but it should also remind of the man Alfred Hauptmann, standing for all those whose similar fates are still unknown until now.

The KEX2 gene of Candida glabrata is required for cell surface integrity

Candida glabrata has emerged as one of the most common causes of candidosis. In order to identify factors that are necessary for viability and pathogenicity of this fungal pathogen, we analysed the role of the KEX2 gene, which codes for a regulatory endoproteinase that is known to process certain virulence factors in Candida albicans. The KEX2 gene from C. glabrata was cloned and found to have 51% and 62% identity and high structural similarities to the homologous counterparts in C. albicans and Saccharomyces cerevisiae. KEX2 was expressed at all time points investigated during growth in complex medium. In order to investigate the role of this putative regulatory proteinase, Kex2-deficient mutants were produced. In addition to known kex2 phenotypes, such as pH and calcium hypersensitivity, the mutants grew in cellular aggregates and were found to be hypersensitive to several antifungal drugs that target the cell membrane, including azoles, amorolfine and amphotericin B. Ultrastructural investigation after exposure to low doses of itraconazole showed azole-specific alterations such as enlarged vacuoles and proliferation of the cytoplasmatic membrane in the kex2 mutants, but not in the control strains. In contrast, antifungals such as 5-flucytosine and hydroxypyridones inhibited growth of the kex2 mutants and the control strains to the same extent. In an in vitro model of oral candidosis, kex2 mutants showed reduced tissue damage in the presence of itraconazole compared with the control infections. These data suggest that Kex2 is involved in the processing of proteins that are essential for cell surface integrity of C. glabrata.

Induction of protective immunity against syngeneic rat cancer cells by expression of the cytosine deaminase suicide gene

The use of the cytosine deaminase (CD)/5-fluorocytosine suicide system as a cancer gene therapy approach enables selective killing of CD-modified cells as well as the ablation of non-modified tumor cells due to a bystander effect that has been suggested to involve the immune system in vivo. Using a stable CD transfectant of the tumorigenic rat adenocarcinoma cell line AS (AS/CD), an antitumoral response against the CD expressing cell line as well as the parental cell line could be induced by stepwise vaccinations in syngeneic animals. AS/CD tumor regression occurred independently of 5-fluorocytosine treatment and was sufficient to protect 37% of the animals against subsequent challenge with tumorigenic doses of the parental AS cell line. Immune rats contained lymphocytes able to specifically lyse CD modified as well as unmodified AS tumor cells in vitro, most likely contributing to the in vivo antitumoral reaction. Thus, the CD suicide system seems to be suitable not only for a local tumor gene therapy but also for the application as therapy of metastatic tumors and minimal residual disease.

Fractionated radiation therapy in combination with adenoviral delivery of the cytosine deaminase gene and 5-fluorocytosine enhances cytotoxic and antitumor effects in human colorectal and cholangiocarcinoma models

Radiosensitization of human gastrointestinal tumors by 5-fluorouracil (5-FU) has been studied in vitro and clinically in human cancer therapy trials. The bacterial enzyme cytosine deaminase (CD) converts the nontoxic prodrug 5-fluorocytosine (5-FC) into 5-FU. Human colon cancer cells stably expressing CD have been shown by other investigators to be sensitized to radiation following treatment with 5-FC. We previously used an adenoviral vector under control of the cytomegalovirus promoter (AdCMVCD) encoding the CD gene in combination with 5-FC and a single fraction of radiation exposure to enhance cytotoxicity to human cholangiocarcinoma cells in vitro and in vivo. The purpose of this study was to determine whether AdCMVCD infection and 5-FC with multiple fraction low-dose radiotherapy results in enhanced cytotoxicity. In the present study, we utilized AdCMVCD and 5-FC with single fraction radiotherapy to demonstrate enhanced cytotoxicity to WiDr human colon carcinoma cells in vitro. Additionally, we tested this gene therapy/prodrug treatment strategy employing a fractionated radiation dosing schema in animal models of WiDr colon carcinoma and SK-ChA-1 cholangiocarcinoma. A prolonged WiDr tumor regrowth delay was obtained with AdCMVCD infection in combination with systemic delivery of 5-FC and fractionated external beam radiation therapy compared with control animals treated without radiation, without 5-FC, or without AdCMVCD. The results of treatment with AdCMVCD + 5-FC + radiation therapy to cholangiocarcinoma xenografts were equivalent to those obtained with systemic 5-FU administration + radiation. Thus, the use of AdCMVCD can be effectively combined with clinically relevant 5-FC and radiation administration schemes to achieve enhanced tumor cell killing and increased control of established tumors of human gastrointestinal malignancies.

Ancient DNA fragments longer than 300 bp

It is widely assumed that ancient DNA (aDNA) extracts contain no authentic templates longer than 300 bp. Here we present results which show that fragments of up to 800 bp in length can be reproducibly amplified from aDNA extracts. The amplification involves the short tandem repeat (STR) locus HUMVWA31A. Authentication of the amplified fragments is carried out by measures of expectancy.

Analytical performance of accelerator mass spectrometry and liquid scintillation counting for detection of 14C-labeled atrazine metabolites in human urine

Accelerator mass spectrometry (AMS) has been applied to the detection of 14C-labeled urinary metabolites of the triazine herbicide, atrazine, and the analytical performance of AMS has been directly compared to that of liquid scintillation counting (LSC). Ten human subjects were given a dermal dose of 14C-labeled atrazine over 24 h, and urine from the subjects was collected over a 7-day period. Concentrations of 14C in the samples have been determined by AMS and LSC and range from 1.8 fmol/mL to 4.3 pmol/mL. Data from these two methods have a correlation coefficient of 0.998 for a linear plot of the entire sample set. Accelerator mass spectrometry provides superior concentration (2.2 vs 27 fmol/mL) and mass (5.5 vs 54,000 amol) detection limits relative to those of LSC for these samples. The precision of the data provided by AMS for low-level samples is 1.7%, and the day-to-day reproducibility of the AMS measurements is 3.9%. Factors limiting AMS detection limits for these samples and ways in which these can be improved are examined.

Double suicide gene (cytosine deaminase and herpes simplex virus thymidine kinase) but not single gene transfer allows reliable elimination of tumor cells in vivo

Suicide genes such as cytosine deaminase (CD) and herpes simplex virus thymidine kinase (TK) encode products that convert nontoxic substances (prodrugs) into toxic metabolites. Suicide gene transfer is currently being used in cancer therapy or can be used as a safety modality. To analyze the reliability of suicide genes as a safety modality for a vaccination study with viable cytokine/B7 gene-modified tumor cells, the individual and combined efficacy of the two suicide genes was compared for in vitro and in vivo cell killing of a murine mammary adenocarcinoma cell line (TS/A). To adapt the system to an in vivo gene delivery situation, bulk cultures cotransfected with the CD and TK gene were used instead of selected clones. In vitro, both CD and TK conferred sensitivity to the respective prodrug but the combined cytotoxic effects of both gene products were always superior. For in vivo analysis BALB/c mice were injected subcutaneously with CD- and TK-modified TS/A cells, treated with prodrugs, and tumor size was evaluated for a period of 100 days. In the in vivo situation the combination of both enzyme/prodrug systems was again most effective. The highest single concentration of 5-FC (500 mg/kg) or GCV (100 mg/kg) was not able to fully protect the animals from developing tumors, whereas a combination of 5-FC (250 mg/kg) and GCV (50 mg/kg) resulted in complete tumor eradication. In nude mice treated in the same way, most CD/TK tumors could not be eliminated. Furthermore, BALB/c mice cured of TS/A-CD/TK tumors developed a systemic tumor immunity against challenge with parental TS/A cells. These findings indicate that reliable tumor elimination by the suicide genes depends on T cells. The cooperative effect of both suicide genes was confirmed in vitro with the human renal cell carcinoma line RCC26. We conclude that TK and CD together, but neither gene alone, act as a safety mechanism for the elimination of tumor cells in a reliable fashion and suggest that a rapid and quantitative antigen release by effective TK- and CD-mediated tumor destruction is necessary for T cell immunity to develop.

Detection of cytosine deaminase in genetically modified tumor cells by specific antibodies

Bacterial cytosine deaminase (CD) converts the non-toxic prodrug 5-fluorocytosine (5-FC) into 5-fluorouracil (5-FU), which is toxic for mammalian cells. Therefore, the CD gene is used in cancer gene therapy to achieve high local concentration of a toxic metabolite without significant systemic toxicity. To allow the detection of CD expression at the protein level, we raised both polyclonal rabbit antisera and a monoclonal antibody (mAb) against a histidine-tagged CD fusion protein. The specificity of the polyclonal antisera and the mAb was confirmed by immunohistochemistry, immunoblot analysis, and immunoprecipitation using CD-expressing tumor cell lines. Furthermore, the antibodies can be used for ELISA assays and flow cytometry. Finally, the CD protein could be demonstrated in frozen tissue sections of CD-modified tumors in a rat tumor model using the anti-CD serum. With these antibodies, CD expression can now be monitored throughout in vitro and in vivo gene transfer studies, including clinical protocols relying on the CD suicide gene strategy.

Adenovirus-assisted lipofection: efficient in vitro gene transfer of luciferase and cytosine deaminase to human smooth muscle cells

Smooth muscle cells (SMC) are a central cell type involved in multiple processes of coronary artery diseases including restenosis and therefore are major target cells for different aspects of gene transfer. Previous attempts to transfect primary arterial cells using different techniques like liposomes, CaPO4 and electroporation resulted in only low transfection efficiency. The development of recombinant adenoviruses dramatically improved the delivery of foreign genes into different cell types including SMC. However, cloning and identification of recombinants remain difficult and time-consuming techniques. The present study demonstrates that a complex consisting of reporter plasmid encoding firefly luciferase (pLUC), polycationic liposomes and replication-deficient adenovirus was able to yield very high in vitro transfection of primary human smooth muscle cells under optimized conditions. The technique of adenovirus-assisted lipofection (AAL) increases transfer and expression of plasmid DNA in human smooth muscle cells in vitro up to 1000-fold compared to lipofection. To verify the applicability of AAL for gene transfer into human smooth muscle cells we studied a gene therapy approach to suppress proliferation of SMC in vitro, using the prokaryotic cytosine deaminase gene (CD) which enables transfected mammalian cells to deaminate 5-fluorocytosine (5-FC) to the highly toxic 5-fluorouracil (5-FU). The effect of a transient CD expression on RNA synthesis was investigated by means of a cotransfection with a RSV-CD expression plasmid and the luciferase reporter plasmid. Western blot analysis demonstrated high expression of CD protein in transfected SMC. Cotransfected SMC demonstrated two-fold less luciferase activity in the presence of 5-FC (5 mmol/l) after 48 h compared to cells transfected with a non-CD coding plasmid. The data demonstrate that a transient expression of CD could be sufficient to reduce the capacity of protein synthesis in human SMC. This simple and effective in vitro transfection method may also be applicable to in vivo delivery of target genes to the vascular wall to inhibit SMC proliferation.

Monitoring gene therapy with cytosine deaminase: in vitro studies using tritiated-5-fluorocytosine

Genetically modified mammalian cells that express the cytosine deaminase (CD) gene are able to convert the nontoxic prodrug 5-fluorocytosine (5-FC) to the toxic metabolite 5-fluorouracil (5-FU). PET with 18F-5-FC may be used for in vivo measurement of CD activity in genetically modified tumors.

METHODS

A human glioblastoma cell line was stably transfected with the Escherichia coli CD gene. After incubation of lysates of CD-expressing cells and control cells with 3H-5-FC high-performance liquid chromatography (HPLC) was performed. The uptake of 5-FC was measured after various incubation times using therapeutic amounts of 5-FC. In addition, saturation and competition experiments with 5-FC and 5-FU were performed. Finally, the efflux was measured.

RESULTS

We found that 3H-5-FU was produced in CD-expressing cells, whereas in the control cells only 3H-5-FC was detected. Moreover, significant amounts of 5-FU were found in the medium of cultured cells, which may account for the bystander effect observed in previous experiments. However, uptake studies revealed a moderate and nonsaturable accumulation of radioactivity in the tumor cells, suggesting that 5-FC enters the cells only through diffusion. Although a significant difference in 5-FC uptake was seen between CD-positive and control cells after 48 hr of incubation, no difference was observed after 2 hr of incubation. Furthermore, a rapid efflux could be demonstrated.

CONCLUSION

5-Fluorocytosine transport may be a limiting factor for this therapeutic procedure. Quantitation with PET has to rely more on dynamic studies and modeling, including HPLC analysis of the plasma, than on nonmodeling approaches.