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The initial studies reported in this dissertation were attempts to induce mutations in those genes which control dissociation in cells of Nei sseria gonorrhoeae. These studies led to an investigation of survival curves of cells grown in liquid media. Instead of survival curves reflecting the diploid nature of gonococci, multiple cell kinetics were observed. It was found that large clumps contained a predominance of cells of the T2 type and that when these clumps were dispersed by DNAase, it appeared that dissociation of T2 was inhibited. The notion of a mechanism of T2 to T4 dissociation being due to genetic transformation was disspelled by these data.

The sinoatrial node (SAN) is the primary pacemaker in mammalian hearts and is vital to cardiac function. Genetic mutations in SAN can result in lose-of-function of ion channels, consequently arouse sinus node dysfunction (SND), Brugada syndrome (BrS) and progressive cardiac conduction disease (PCCD). The mechanisms underlying the he pathogenesis for cardiac pacemaker dysfunctions associated with genetic mutations has not been defined. In this project, by using computer modeling, mechanisms by which the HCN4 mutations impair cardiac pacemaking and possible pro-arrhythmic effects of ivabradine were investigated. Action potential (AP) models for rabbit sinoatrial node cells were modified to incorporate experimentally reported If changes induced by HCN4 gene mutations. At both the cellular and intact SAN-atrium tissue level, If reduction due to the HCN4 mutations slowed down pacemaking. At the tissue level, these mutations compromised the AP conduction across the SAN-atrium, leading to a possible sinus arrest or SAN exit block. Moreover, vagal nerve activity could amplify the bradycardiac effects of the HCN4 gene mutations, leading to sinus arrest and SAN exit block that was not observed with the mutations or ACh alone. Similarly, SND associated with SCN5A mutations and acquired cardiac conditions were studied. 1) Mathematical models of rabbit SAN cells and 2D tissue models were modified to investigate SAN function and intracardiac conduction in a murine model of long QT syndrome type 3. A prolonged tail current INa,L was introduced and incorporated with a normal INa,T to test the SAN pacemaker function and AP conduction from the SAN to atrial septum. Simulation results showed that a combined reduction in INa,T and introduction of INa,L achieved alterations in both pacemaking rate and conduction. 2) Mathematical models of mouse SAN cells were modified to investigate the mechanisms underlies the SAN associated with SCN5A deficiency and aging. A coupled SAN-atrium cell model was developed to replicate the experimentally observed slowing of SAN conduction with aging and SCN5A-disruption The modelling studies reconstructed the physiological mechanisms by which both aging and SCN5A-disruption lead to SND, thereby drawing parallels between these and similar conduction changes in the ventricle that occur in the possibly related condition of PCCD. At last, a 2D anatomically based model of the SAN-atrium was constructed. This model successfully reproduced the effects of vagal nerve stimulation and SCN5A-E161K gene mutation on spontaneous activity of the SAN and AP conduction across the SAN-atrium.

Ataxia Telangiectasia Mutated (ATM) gene helps to repair DNA damage and that increased cancer risks are associated with having a mutation in an ATM gene. ATM gene is newer compared to other known hereditary cancer genes. We present a rare care of 66-year-old female with extensive personal and family history of breast and pancreatic cancer had negative imaging surveillance until recent systemic imaging showed new pancreatic head 2.5x2.5 cm mass. Endoscopic ultrasound confirmed invasion of superior mesenteric vein with near confluence. No regional adenopathy was seen. She was felt to be borderline resectable and neoadjuavant chemotherapy was planned. She had a personal history of right breast cancer diagnosed in 1998 status post lumpectomy and axillary lymph node dissection and adjuvant chemotherapy with CMF regimen x 5 cycles and radiation therapy and endocrine therapy with tamoxifen for 5 years. In 2011 she was also diagnosed with rectal well to moderately differentiated adenocarcinoma status post abdominoperitoneal resection on 3/15/2011, 36 lymph nodes were negative, but the surgical circumferential radial margin was positive. She underwent adjuvant radiation therapy with total dose of 45 Gy. There was recurrence in vaginal and bladder wall adenocarcinoma in 2014 for which patient underwent an anterior exenteration. Pathology felt this was endocervical origin of malignancy and patient received megace therapy for 3 years based on hormone receptor positive status. For new diagnosis of pancreatic adenocarcinoma, she was started on Gemcitabine and Abraxane chemotherapy. Given extensive personal and family history of malignancy, she was referred to genetic counsellor. Hereditary cancers panel at invitae laboratory was positive for a heterozygous pathological variant in the ATM gene deletion (exons 62-63). ATM gene is associated with an increased risk for autosomal dominant breast, pancreatic and prostate cancer. Close relatives (children, siblings, and each parent) have up to a 50% chance of being a carrier of this variant. It is essential for treating physicians to educate patients and family members on the risk for subsequent malignancies.

Background: Patent Foramen Ovale (PFO), a remnant of the foetal circulation, is emerging as a new cause of disease. It has been found to be associated with cryptogenic stroke in young adults, peripheral arterial embolism and neurological decompression sickness in divers. The detection of PFO remains a diagnostic challenge; transoesophageal echocardiogram being currently considered the ‘gold standard’. The development of a non-invasive technique is crucial for the identification of a venous-to-arterial shunt (v-aCS) which may permit paradoxical embolism. Little is known about the genetic basis of PFO and our limited knowledge is based on animal studies and gene mutations detected in patients with other cardiac septal defects. Methods: Study 1: PFO Detection and Evaluation: This study was designed to evaluate transcranial Doppler (TCD), transthoracic echocardiogram (TTE) and transoesophageal echocardiogram (TOE) with administration of contrast via arm and femoral veins. We then developed a standardized protocol for PFO detection and quantification using TCD. Study 2: PFO and Migraine: The PFO detection protocol developed from the first study formed the diagnostic technique to detect v-aCS in an adequately powered matched case control study to explore the association between PFO and migraine. Study 3: The Genetic basis of PFO: This study was designed to explore the genetic basis of a PFO using a candidate gene approach. Results: Study 1 - PFO Detection Study: When compared with TOE with femoral vein contrast injection as the ‘gold standard’, TCD with arm vein contrast was 100% sensitive and 97.4% specific for detecting a PFO. We defined a PFO positive (+ve) study on TCD as > 15 microbubbles entering the cerebral circulation, on TCD following arm vein injection and >16 microbubbles with a femoral contrast injection. A ‘major’ PFO+ve v-aCS was defined as >35 microbubbles with arm vein injection or >90 microbubbles with femoral vein injection. We then developed a new diagnostic pathway for PFO detection in clinical practice. Study 2 - PFO Migraine study: A significant difference in prevalence of v-aCS between migraine with aura M+A) and their matched controls was demonstrated with adjusted OR=3.72 (1.48-9.38) p=0.005 for a PFO+ve v-aCS, and a highly significant difference between M+A and controls for a ‘major’ PFO+ve v-aCS with adjusted OR = 6.38 (1.89 – 21.48) p = 0.003. There was significant association with APC resistance and migraine on thrombophilia screen. Study 3 - The PFO Genetics Study: This study detected mutations of GATA4 and NKX2-5 in both PFO+ve cases and PFO-ve controls. Two novel non synonymous mutations of GATA4, c.461T>A and c.994G>A were found only in PFO positive individuals and may be associated with a PFO. All the PFO+ve cases with a GATA4 gene mutation had a major PFO+ve v-aCSConclusion:TCD detects PFO with a sensitivity of 100% and specificity of 92.3% and is the most reliable non-invasive technique for PFO detection. When arm vein injections are used both cough and valsalva provocation is essential. There was a highly significant association between PFO+ve v- aCS and M+A, especially with a ‘major’ PFO+ve v-aCS. GATA 4 mutations though infrequent were found PFO+ve cases and all had major v-aCS.

Yes / The revolution in Big Data has opened the gate for new research challenges in biomedical science. The aim of this study was to investigate whether germ-line gene mutations are a significant factor in 29 major primary human cancers. Using data obtained from multiple biological databases, we identified 424 genes from 8879 cancer mutation records. By integrating these gene mutation records a human cancer map was constructed from which several key results were obtained. These include the observations that missense/nonsense and regulatory mutations might play central role in connecting cancers/genes, and tend to be distributed in all chromosomes. This suggests that, of all mutation classes missense/nonsense and regulatory mutation classes are over-expressed in human genome and so are likely to have a significant impact on human cancer aetiology and pathomechanism. This offers new insights into how the distribution and interconnections of gene mutations influence the development of cancers.

The thesis The analysis of genetic factors of breast cancer by NGS deals with the current serious problematics of breast cancer from the perspective of genetic predisposition. Breast cancer is one of the most common tumors in women. Every year more than 7000 women are diagnosed with this disease and the mortality rate in the Czech Republic is nearly 2000 cases. Of the total number of patients diagnosed with breast cancer, approximately ten percent of patients have congenital mutations in one of the predisposing genes that cause a significantly increased risk of developing a cancer. More than half of these mutations occur in germline mutations of the BRCA1 or BRCA2 genes, others include a number of other genes, eg tp53, CDH1, PTEN, STK11, ATM, PALB2, CHEK2.Early diagnosis and identification of persons with increased risk of developing breast cancer is of key importance for their inclusion in preventive programs. Therefore, the thesis aims to testing genes that can cause a breast cancer. In the thesis, 219 known and candidate predisposition genes were analyzed in a group of 263 non-selected breast cancer patients using a targeted panel NGS, the Illumina platform. Selected identified suspect variants were further confirmed by Sanger sequencing. The aim of this work was also a mutational analysis of...