Genomic profiling of Acute lymphoblastic leukemia in ataxia telangiectasia patients reveals tight link between ATM mutations and chromothripsis.

Recent developments in sequencing technologies led to the discovery of a novel form of genomic instability, termed chromothripsis. This catastrophic genomic event, involved in tumorigenesis, is characterized by tens to hundreds of simultaneously acquired locally clustered rearrangements on one chromosome. We hypothesized that leukemias developing in individuals with Ataxia Telangiectasia, who are born with two mutated copies of the ATM gene, an essential guardian of genome stability, would show a higher prevalence of chromothripsis due to the associated defect in DNA double-strand break repair. Using whole-genome sequencing, fluorescence in situ hybridization and RNA sequencing, we characterized the genomic landscape of Acute Lymphoblastic Leukemia (ALL) arising in patients with Ataxia Telangiectasia. We detected a high frequency of chromothriptic events in these tumors, specifically on acrocentric chromosomes, as compared with tumors from individuals with other types of DNA repair syndromes (27 cases total, 10 with Ataxia Telangiectasia). Our data suggest that the genomic landscape of Ataxia Telangiectasia ALL is clearly distinct from that of sporadic ALL. Mechanistically, short telomeres and compromised DNA damage response in cells of Ataxia Telangiectasia patients may be linked with frequent chromothripsis. Furthermore, we show that ATM loss is associated with increased chromothripsis prevalence in additional tumor entities.

Identification of a genetically defined ultra-high-risk group in relapsed pediatric T-lymphoblastic leukemia.

In the search for genes that define critical steps of relapse in pediatric T-cell acute lymphoblastic leukemia (T-ALL) and can serve as prognostic markers, we performed targeted sequencing of 313 leukemia-related genes in 214 patients: 67 samples collected at the time of relapse and 147 at initial diagnosis. As relapse-specific genetic events, we identified activating mutations in NT5C2 (P=0.0001, Fisher's exact test), inactivation of TP53 (P=0.0007, Fisher's exact test) and duplication of chr17:q11.2-24.3 (P=0.0068, Fisher's exact test) in 32/67 of T-ALL relapse samples. Alterations of TP53 were frequently homozygous events, which significantly correlated with higher rates of copy number alterations in other genes compared with wild-type TP53 (P=0.0004, Mann-Whitney's test). We subsequently focused on mutations with prognostic impact and identified genes governing DNA integrity (TP53, n=8; USP7, n=4; MSH6, n=4), having key roles in the RAS signaling pathway (KRAS, NRAS, n=8), as well as IL7R (n=4) and CNOT3 (n=4) to be exclusively mutated in fatal relapses. These markers recognize 24/49 patients with a second event. In 17 of these patients with mostly refractory relapse and dire need for efficient treatment, we identified candidate targets for personalized therapy with p53 reactivating compounds, MEK inhibitors or JAK/STAT-inhibitors that may be incorporated in future treatment strategies.

Perfil bioquímico sérico de equinos clinicamente sadios da raça Campeiro / Serum biochemical profile from clinically healthy Campeiro horses

Amostras de sangue foram obtidas de 138 equinos registrados da raça Campeiro, com idade média de 9,7±5,4 anos, sendo 14 machos (10,15%) e 124 fêmeas (89,85%). Observaram-se valores médios da atividade sérica de GGT: 13,73±4,08 U/L; AST: 246,34±72,87U/L; ALT: 5,13±1,18U/L; FA: 284,32±53,33UI/L; CK: 132,54±72,25U/L; LDH: 511,38±143,65U/L; e das concentrações séricas de ureia: 38,65±12,62mg/dL e de creatinina: 1,24±0,24mg/dL. Os valores médios de AST, FA, ALT, ureia e creatinina foram semelhantes aos propostos na literatura para outras raças. Os valores de CK, GGT e LDH foram superiores aos comumente utilizados como referências. Não houve diferença nas concentrações de nenhum dos componentes séricos avaliados nas diferentes idades analisadas. Maiores valores médios nas concentrações de ureia e menores de creatinina foram observados nas fêmeas em relação aos machos, assim como a maior atividade sérica de FA em fêmeas gestantes em relação às éguas vazias. O perfil bioquímico sérico de equinos sadios da raça Campeiro apresenta variações peculiares que devem ser levadas em consideração na interpretação de exames laboratoriais.(AU)

Blood samples were obtained from 138 equines of the Campeiro breed with mean ages of 9.7±5.4 years, including 14 males (10.15%) and 124 mares (89.85%). Mean values of serum of GGT: 13.73 ± 4.08U/L; AST: 246.34±72.87U/L; ALT 5.13±1.18U/L; FA: 284.32±53.33IU/L; CK: 132.54±72.25U/L; LDH: 511.38±143.65U/L; and serum urea: 38.65±12.62mg/dL and creatinine: 1.24±0.24mg/dL were observed. The mean values of AST, FA, ALT, urea and creatinine were similar to those proposed in the literature for other breeds. The CK values, GGT, and LDH were higher than those commonly used as references. There was no difference in the concentrations of any of the serum components evaluated at different ages analyzed. Further average values in the lower urea concentrations and creatinine were observed in females compared to males, as well as the higher serum activity of FA in pregnant mares in relation to non-pregnant. Serum biochemical profile of healthy horses of the Campeiro breed presents peculiar variations that must be taken into consideration in the interpretation of laboratory tests.(AU)

Biometrics of hoof balance in equids / Biometria do equilíbrio podal de equídeos

Differences in hoof balance between horses, mules and donkeys were identified in order to form more specific considerations for proper management of the animals. Measurements of the natural dimensions of hooves in sixty animals were used: 20 horses from the Crioulo breed, 20 mules and 20 donkeys from the Pêga breed. Liveweight was estimated using the correlation equations in each species by heart girth. Using a caliper rule, tape measure and hoof gauge, measurements of the length and width of the frog, hoof height, angle of heel, medial and lateral dorsal length, angle of the toe and crown circumference of the hooves of forelimbs and hindlimb were taken. Within each group the hooves of the hindlimbs exhibited narrower measurements than the hooves of the forelimbs and no difference was observed between the hoof angle of both members of groups. The conformation of the hooves of donkeys is shown to be substantially different from that observed in horses, the mules being in an intermediate condition, being smaller, angled and robust frog and proportionally more developed. Similarly, the hooves of donkeys provide greater support area compared to mules and horses, in descending order, even being dimensionally smaller. We conclude that the hooves of horses, mules and donkeys, have specific patterns of geometric balance that must be taken into consideration at the time of trimming and imbalance inferences.(AU)

O objetivo deste trabalho foi determinar o equilíbrio dos cascos de equídeos. Foram utilizados 60 animais, sendo estes: 20 equinos da raça Crioula, 20 muares e 20 asininos da raça Pêga. O peso vivo foi estimado por meio de equações de correlação com o perímetro torácico específico a cada espécie. Utilizando-se paquímetro, fita métrica e podogoniômetro, foram mensurados comprimento e largura da ranilha e do casco, altura e ângulo dos talões medial e lateral, comprimento dorsal e ângulo da pinça e perímetro da banda coronária dos cascos dos membros torácicos e pélvicos. Dentro de cada grupo, observou-se que os cascos dos membros pélvicos exibem-se mais estreitos que os cascos dos membros torácicos, e não houve diferença entre o ângulo das pinças de ambos os grupos de membros. A conformação dos cascos dos asininos mostra-se substancialmente divergente do observado nos equinos, estando os muares numa condição intermediária, sendo aqueles menores, mais angulados e com ranilha robusta e proporcionalmente mais desenvolvida. Da mesma forma, os cascos dos asininos proporcionam maior área de apoio em relação aos muares e equinos, em ordem decrescente, mesmo sendo dimensionalmente menores. Conclui-se que os cascos de equinos, muares e asininos apresentam padrões de equilíbrio geométrico específicos, que devem ser levados em consideração no momento do casqueamento e na inferência de desequilíbrios.(AU)

Simultaneous computed tomography-guided biopsy and radiofrequency ablation of solitary pulmonary malignancy in high-risk patients.

BACKGROUND: In recent years experience has been accumulated in percutaneous radiofrequency ablation (RFA) of lung malignancies in nonsurgical patients. OBJECTIVES: In this study, we retrospectively evaluated a simultaneous diagnostic and therapeutic approach including CT-guided biopsy followed immediately by RFA of solitary malignant pulmonary lesions. METHODS: CT-guided transthoracic core needle biopsy of solitary pulmonary lesions suspicious for malignancy was performed and histology was proven based on immediate frozen sections. RFA probes were placed into the pulmonary tumors under CT guidance and the ablation was performed subsequently. The procedure-related morbidity was analyzed. Follow-up included a CT scan and pulmonary function parameters. RESULTS: A total of 33 CT-guided biopsies and subsequent RFA within a single procedure were performed. Morbidity of CT-guided biopsy included pulmonary hemorrhage (24%) and a mild pneumothorax (12%) without need for further interventions. The RFA procedure was not aggravated by the previous biopsy. The rate of pneumothorax requiring chest tube following RFA was 21%. Local tumor control was achieved in 77% with a median follow-up of 12 months. The morbidity of the CT-guided biopsy had no statistical impact on the local recurrence rate. CONCLUSIONS: The simultaneous diagnostic and therapeutic approach including CT-guided biopsy followed immediately by RFA of solitary malignant pulmonary lesions is a safe procedure. The potential of this combined approach is to avoid unnecessary therapies and to perform adequate therapies based on histology. Taking the local control rate into account, this approach should only be performed in those patients who are unable to undergo or who refuse surgery.

[18-year-old woman with an ovarian tumour detected by coincidence]. / 18-jährige Frau mit zufällig entdecktem Ovarialtumor.

Massive ovarian edema (MOE) is a rare, benign disease of young women. Because preoperatively in most cases the differential diagnosis primarily appears to indicate the presence of a malignant tumour, there is a risk that these patients will be subjected to unnecessary overtreatment. In the case of the 18-year-old patient described here, on the basis of the preoperative data the suspected clinical diagnosis was polycystic ovarian (PCO) syndrome. In the MRI the enlarged ovary was interpreted as a mucous tumour. The laparotomy showed a smooth-walled, opalescent ovarian tumour with adnexal torsion. Histopathological examination of the adnexectomy specimen gave the diagnosis of a massive ovarian edema (MOE). Therapeutically, a wedge-shaped excision, immediate-section histology and derotation and suspension of the ovary would have been sufficient. Unnecessary overtreatment can be avoided in young women with enlarged ovaries, if MOE is included in the differential diagnosis and if the characteristic sonography, MRI and macroscopy findings are known.

Diagnosis of pulmonary metastases with helical CT: the effect of imaging techniques.

OBJECTIVE: Survival in patients after surgical resection of pulmonary metastases correlates with the complete resection of all metastatic deposits. The purpose of this study was to evaluate the additional value of helical CT to see whether the slice thickness and the reading environment was a factor determining the accuracy of helical scans. METHODS: Between 2004 and 2007, 93 patients (62 men, 31 women) underwent complete resection of pulmonary metastases by open thoracotomy. A total of 125 thoracotomies were performed with manual palpation of the involved lung. We retrospectively examined the helical CT findings obtained using a 5-mm slice thickness in a routine preoperative analysis, and within this study a second reading was performed independently, using 3-mm slice thickness image sets. The CT images were evaluated in a consensus between two radiologists. RESULTS: Computed tomography scanning was performed a median of 12 days before thoracotomy (range 1-121 days). Analysis of helical CT in 5-mm slice thickness detected metastases with a sensitivity of 83.7 % whereas a 3-mm slice thickness had a sensitivity of 88.8 %. There were statistically significantly more lesions using helical CT and a 3-mm slice thickness technique than with the 5-mm slice thickness technique, compared to the surgical results ( P = 0.002). This was also found with regard to nodules which were finally histologically confirmed as lung metastases ( P = 0.014). CONCLUSIONS: We conclude that a reduced slice thickness may have an important positive impact on the treatment and outcome of patients with pulmonary metastases. The use of 3-mm slice thickness helical CT may raise the sensitivity for pulmonary metastases detection compared to 5-mm images, but the rate of false positive results may also increase.

[Placental site trophoblastic tumor: case report and review of literature]. / Placental site trophoblastic tumor--Ein Fallbericht und Literaturübersicht.

A 32-year-old para 3 patient is presented having suffered from a silent uterine rupture on the occasion of her second and third Caesarean sections. After the third Caesarean section, there was light uterine bleeding whilst the patient breastfed for five months. Amenorrhoea then ensued due to oral contraception. Regular clinical and ultrasound checks revealed negative serum beta-HCG values and retrovesicular resistance, which increased in size after 18 months and became symptomatic. Because the patient's family was complete, abdominal hysterectomy without adnexectomy was performed. Histology revealed a placental site trophoblastic tumour (PSTT). This is a rare tumour with malignant potential, whose prognosis depends on the stage of the primary tumour, the period of time between the last pregnancy and onset of disease, the patient's age, and the rate of mitosis, and whose progress cannot be assessed using the WHO Prognostic Index Score for Gestational Trophoblastic Disease. In therapeutic terms, hysterectomy is recommended. Chemosensitivity is low and, due to the infrequency of the tumours, the most suitable chemotherapy scheme is unknown. In the case of metastasising or recurrent PSTT, the EP/EMA regime has proved to be most effective.

[Uterine tumor resembling ovarian sex cord tumor: case report and review of literature]. / Uteriner Tumor mit keimstrang-ahnlicher Differenzierung (UTROSCT): Fallbericht und Literaturübersicht.

Uterine tumours with sex cord-like differentiation are rare. They are observed, pre- and post-menopausal women between the fourth and the sixth decade and manifest themselves by haemorrhagic anomalies and usually enlarged uteri, misinterpreted as uterus myomatosus. One distinguishes between two groups on account of the share of sex cord-like elements, i.e. tumours with only focal sex cord-like differentiation with a tendency to relapses and metastatic spread, and tumours with predominant differentiation in the sense of ovarian sex cord tumours with a good prognosis because surgical treatment alone often leads to relapse-free survival. Because of the tumours' rarity, there are no randomized studies as to an optimal therapy. Since there have been reports on endometrial stromal sarcoma with low malignant potential in adjuvant therapy of breast cancer with Tamoxifen, one can assume that this entity will occur more frequently in future.

[Primary adenocarcinoma of the appendix as differential diagnosis of advanced ovarian carcinoma]. / Das primäre Adenokarzinom der Appendix als Differentialdiagnose des fortgeschrittenen Ovarialkarzinoms.

Malignant tumours of the appendix are rare. They are usually carcinoid tumours that must be distinguished from extremely rare adenocarcinomas. Metastatic mucinous adenocarcinomas of the appendix are only reported as case histories. In clinical terms, the tumours usually manifest themselves as acute appendicitis, as ruptured appendicitis, as a tumour in the right lower abdominal quadrant or as a pelvic tumour, which are generally mistaken for an ovarian tumour with the same sonographic image. Advanced primary adenocarcinomas of the appendix with ovarian metastases cannot be distinguished intraoperatively from a FIGO III ovarian carcinoma. The pathologist makes the definitive diagnosis. These characteristics also apply to the case presented here. Surgical therapy of the isolated primary appendiceal carcinoma consists of a hemicolectomy--an appendectomy in favourable cases--and, in the case of a metastasised carcinoma, according to the guidelines for an advanced ovarian or colon carcinoma. The effect of chemotherapy is insufficiently documented.

[Uterine leiomyoma as cause of erythrocytosis]. / Uterus myomatosus als Ursache für Erythrozytose.

Myoma-induced erythrocytosis is a rare clinical picture which is probably largely misunderstood. Pre- and postmenopausal women are affected. The characteristics of this syndrome are raised haemoglobin and haematocrit values, erythrocytosis at normal plasma volumes and the fact that these values are promptly and permanently corrected by myomectomy or hysterectomy. Myomatous erythrocytosis syndrome (MES) can be the explanation of normal haematological parameters in patients with myoma-related hypermenorrhoea and menorrhagia.

[Experience in a suburban hospital with premature termination of pregnancy in the second trimester]. / Erfahrungen mit der vorzeitigen Schwangerschaftsbeendigung im zweiten Trimenon am peripheren Spital.

The present study was performed between 1992 and 1998 and had the aim of examining the activity and side-effects of intravenously administered sulprostone for the induction of abortion in the second trimester. 160 patients were admitted to hospital. 3 were submitted to a hysterectomy; 3 underwent an abortion after cervical priming with Prostin E2 Gel (0.25 mg/ml), 154 were repeatedly treated with an infusion of sulprostone for 6 hours (500 microg Nalodor, 3 A/1000 ml 0.9% NaCl, 250 microg/h (equivalent to 4.17 microg or ca. 55 drops per min.). The mean interval for induction of abortion was 16 h 56 min; 53% of the abortions occurred within 12h; 95% of the abortions occurred within 48 h. Two inductions were unsuccessful. 12 women suffered from atonic bleeding. This study demonstrated that sulprostone infusions are suitable for the induction of abortions in the second trimester and that side-effects are rare. Particular attention must be paid to the complication of bleeding.

[Differential abdominal pain diagnosis in gynecologic and obstetric general practice]. / Zur Differentialdiagnose abdomineller Schmerzen in der gynäkologisch-geburtshilflichen Praxis.

Abdominal pains are frequent complaints in specialist and GP practices and may be evidence of an acute or chronic condition. The complexity and diversity of possible causes demand an interdisciplinary approach, where appropriate, but never a polypharmaceutical approach. If the aetiology of an acute pain cannot be established within less than six to eight hours in a GP practice, the patient should be referred to an interdisciplinary emergency unit with a request to break down the differential diagnosis and push ahead with the diagnostic procedure. Gynaecology departments are confronted with some rare diagnoses which, if made promptly, will prove to be of crucial prognostic significance. Chronic abdominal pains call for interdisciplinary problem-solving.

Identification and characterisation of the gene TWIST NEIGHBOR (TWISTNB) located in the microdeletion syndrome 7p21 region.

We have characterised a 2.4-Mb genomic sequence of a smallest region of overlap (SRO) deleted in the human microdeletion syndrome 7p21 by in silico analysis. Patients harbouring this minimal deletion present in addition to the clinical features of Saethre-Chotzen syndrome (MIM 101400) a distinct learning disability. This genomic region shows a very low gene content. Besides the transcription factor gene TWIST, the Histone Deacetylase 9 (HDAC9), Sorting Nexin 13 (SNX13) and an evolutionarily conserved bHLH transcription factor gene Nephew of Atonal 3 (HNATO3) have been detected previously. Here we describe the localisation and characterisation of the TWIST NEIGHBOR (TWISTNB) gene. Comparison of the predicted proteins of human TWISTNB and mouse Twistnb shows a high degree of conservation. Northern blot analysis of human fetal and adult tissues shows ubiquitous expression in all tissues tested.

Saethre-Chotzen syndrome and hyper IgE syndrome in a patient with a novel 11 bp deletion of the TWIST gene.

Molecular genetic studies in a seven-year-old boy and his mother demonstrated a novel 11 bp deletion in the TWIST gene (127del11), causing Saethre-Chotzen syndrome. The mother had rather mild signs of the Saethre-Chotzen syndrome; however, her son presented with marked acrocephalosyndactyly type 3, leading to craniotomy at three years. He also had recurrent infections and laboratory findings comparable with the hyper IgE syndrome, a rare primary immunodeficiency disorder. It is likely that the 11bp deletion caused the Saethre-Chotzen syndrome in the patient and his mother, and another, not yet identified genetic defect, seen in the patient but not in the mother, is responsible for the hyper IgE phenotype. A combination of these two congenital conditions has not been described to date.

Isolation and characterization of the human forkhead gene FOXQ1.

We have isolated a human genomic and cDNA clone that encodes a protein of 403 amino acids and belongs to the family of the FOX transcription factors (previously called HNF-3/forkhead transcription factors). The 2.7-kb transcript of the human FOXQ1 gene is expressed predominantly in the stomach, trachea, bladder and salivary gland. Additionally, overexpression of human FOXQ1 was shown in colorectal adenocarcinoma and lung carcinoma cell lines. The FOXQ1 gene is located on chromosome 6p23-25. Databank analysis shows 82% homology with the mouse Foxq1 gene (formerly Hfh-1L) and with a revised sequence of the rat FoxQ1 gene (formerly HFH-1). The DNA-binding motif, named HNF-3/forkhead domain, is well conserved, showing 100% identity in human, mouse, and rat. The human protein sequence contains two putative transcriptional activation domains, which share a high amino acid identity with the corresponding mouse and rat domains.

The cellular uptake of anandamide is coupled to its breakdown by fatty-acid amide hydrolase.

Anandamide is an endogenous compound that acts as an agonist at cannabinoid receptors. It is inactivated via intracellular degradation after its uptake into cells by a carrier-mediated process that depends upon a concentration gradient. The fate of anandamide in those cells containing an amidase called fatty-acid amide hydrolase (FAAH) is hydrolysis to arachidonic acid and ethanolamine. The active site nucleophilic serine of FAAH is inactivated by a variety of inhibitors including methylarachidonylfluorophosphonate (MAFP) and palmitylsulfonyl fluoride. In the current report, the net uptake of anandamide in cultured neuroblastoma (N18) and glioma (C6) cells, which contain FAAH, was decreased by nearly 50% after 6 min of incubation in the presence of MAFP. Uptake in laryngeal carcinoma (Hep2) cells, which lack FAAH, is not inhibited by MAFP. Free anandamide was found in all MAFP-treated cells and in control Hep2 cells, whereas phospholipid was the main product in N18 and C6 control cells when analyzed by TLC. The intracellular concentration of anandamide in N18, C6, and Hep2 cells was up to 18-fold greater than the extracellular concentration of 100 nm, which strongly suggests that it is sequestered within the cell by binding to membranes or proteins. The accumulation of anandamide and/or its breakdown products was found to vary among the different cell types, and this correlated approximately with the amount of FAAH activity, suggesting that the breakdown of anandamide is in part a driving force for uptake. This was shown most clearly in Hep2 cells transfected with FAAH. The uptake in these cells was 2-fold greater than in vector-transfected or untransfected Hep2 cells. Therefore, it appears that FAAH inhibitors reduce anandamide uptake by cells by shifting the anandamide concentration gradient in a direction that favors equilibrium. Because inhibition of FAAH increases the levels of extracellular anandamide, it may be a useful target for the design of therapeutic agents.

Initial lesions of vascular aging disease (arteriosclerosis).

BACKGROUND: In contrast to the well-known morphologic lesions of arteriosclerosis, the initial changes of the disease are less obvious. Commonly, functional disturbances of the endothelium, endothelial dysfunction, are suggested. On the other hand the significance of age-dependent changes in the extracellular matrix with their important role in vessel wall permeability and other features associated with arteriosclerosis should not be overlooked. New topics deal with possible infectious factors, the genetic basis of the disease and the particularities of the unstable atheroma. OBJECTIVE: Alterations in nitric monoxide and endothelin-1 balance of the endothelium are the key events in the initiation of arteriosclerosis induced by oxidized lipoproteins, cigarette smoking and endotoxin. This frequently supposed mechanism contrasts with earlier opinions on the primary alterations in glycosaminoglycan metabolism and other components of the extracellular matrix against atherogenic factors like hypertension, stress and physical inactivity. Based on a survey of the literature and our own experimental experiences, these changes in connection with the morphometrically determined age-conditioned increase in vascular wall thickness and the above-mentioned new topics on arteriosclerosis were analyzed. CONCLUSION: The initial lesions of arteriosclerosis starting in youth seem to be fundamentally different from those beginning in old age. The first step in the development of fatty streaks in the arteries of young people is endothelial dysfunction with a decreased formation of nitric monoxide and an increased expression of adhesion molecules. In comparison the genesis of arteriosclerosis in advanced age is characterized by metabolic changes in the endothelium combined with age-conditioned alterations in the extracellular matrix resulting in faster progression of the disease in old age. The multicausal genesis of arteriosclerosis cannot be doubted even if cooperation with infectious factors cannot be excluded. The histopathologic peculiarities of unstable atheroma are described.

[Serous cystadenofibroma of the epiploic appendix. A tumor of the secondary müllerian system: case report and review of the literature]. / Seröses Zystadenofibrom der Appendix epiploica. Ein Tumor des sekundären Müller-Systems--Fallbericht und Literaturübersicht.

We present a case of serous cystadenofibroma 2 cm in diameter in the epiploic appendix of the sigmoid as incidental finding in a 72-year-old patient who underwent hysterectomy and oophorectomy for endometrial carcinoma. The tumor showed the same histology as analogous tumors of the ovary and was associated with endosalpingiosis. Further findings were large adhesions between the epiploic appendices of the sigmoid and the parietal peritoneum and atypical cells in the peritoneal washings. Both may be explained by occult peritoneal endosalpingiosis. The histogenesis, histology, and locations of extraovarian müllerian tumors are reviewed.

Heat shock-induced arrests in different cell cycle phases of rat C6-glioma cells are attenuated in heat shock-primed thermotolerant cells.

The response kinetics of rat C6 glioma cells to heat shock was investigated by means of flow cytometric DNA measurements and western blot analysis of HSP levels. The results showed that the effects on cell cycle progression are dependent on the cell cycle phase at which heat shock is applied, leading to either G1 or G2/M arrest in randomly proliferating cells. When synchronous cultures were stressed during G0 they were arrested with G1 DNA content and showed prolongation of S and G2 phases after release from the block. In proliferating cells, HSC70 and HSP68 were induced during the recovery and reached maximum levels just before cells were released from the cell cycle blocks. Hyperthermic pretreatment induced thermotolerance both in asynchronous and synchronous cultures as evidenced by the reduced arrest of cell cycle progression after the second heat shock. Thermotolerance development was independent of the cell cycle phase. Pre-treated cells already had high HSP levels and did not further increase the amount of HSP after the second treatment. However, as in unprimed cells, HSP reduction coincided with the release from the cell cycle blocks. These results imply that the cell cycle machinery can be rendered thermotolerant by heat shock pretreatment and supports the assumption that HSP70 family members might be involved in thermotolerance development.