Practicable approaches to facilitate rapid and accurate molecular cytogenetic mapping in birds and mammals.

Molecular cytogenetic mapping by FISH is a common feature of most genome projects as it provides a global, low-resolution overview of the genome and facilitates comparative genomics. An essential prerequisite for cytogenetic mapping is the ability to identify accurately the chromosome on which the clone (e.g. BAC) resides. This is not usually a barrier to human mapping as knowledge of the human karyotype is commonplace. For other species however accurate assignment can be problematic either because, as in birds, the karyotype is too complex to analyze by standard means or because of the paucity of individuals skilled to perform the karyotyping. Using chicken as a model we have developed a reproducible approach for accurate cytogenetic mapping that involves: a single colour FISH, measurement of the ratio of the size of the signal bearing chromosome to that of chromosome 8, and final assignment through a small series of dual colour experiments. Reference values for size ratios were established using base pair estimate information from the Ensembl browser. By this method cytogenetic mapping to highly complex karyotypes can be achieved in a small number of simple steps. We have also developed and tested a karyotyping tutorial programme adapted from one previously reported in this journal. That is, we have used pig as an example of a model species with a relatively tractable karyotype and demonstrated that scientists and students, even after only one hour using our tutorial, can readily identify pig chromosomes and thus make appropriate assignments using FISH. Simple, practicable means often provide preferable solutions than complex alternatives (e.g. m-FISH) to the solution of scientific problems. Such is the case for the approaches described here.

Thoracoscopy versus thoracotomy: indications and advantages.

Although the diagnosis and treatment of intrathoracic diseases have been affected by the use of thoracoscopy, the indications and advantages of this procedure are poorly defined. To review the indications and results in a community practice, 52 consecutive cases of thoracoscopy were reviewed and the postoperative courses were compared to a control group of 43 simultaneous thoracotomies. Operative indications for thoracoscopy included investigation or treatment of a lung mass (n = 33), spontaneous pneumothorax (n = 10), mediastinal mass (n = 4), pleural effusion (n = 2), mesothelioma (n = 2), and a ruptured hemidiaphragm (n = 1). General endotracheal anesthesia was used in each case. Overall, thoracoscopy was successful in 40 cases (77%). Conversion to formal thoracotomy was required in 14 cases (27%) secondary to poor visualization or to aid in further dissection. Compared to thoracotomy, complication rates were less (7.6 vs 16.2%), hospital stay shorter (5.5 vs 8 days), ICU stay shorter (0 vs 2 days) and pleural drainage time less (2 vs 5 days) in the thoracoscopy group. In summary, 73% of the patients in this study who formerly would have undergone thoracotomy were successfully managed with thoracoscopy alone, with acceptable morbidity and mortality. These data define the indications, morbidity, and mortality of thoracoscopy and suggest that thoracoscopy may emerge as the procedure of choice in the diagnosis and management of many thoracic diseases.