Expression of delayed toxicity and lethal mutations in the progeny of human cells surviving exposure to radiation and other environmental mutagens

PURPOSE

Delayed expression of lethal mutations in the progeny of cells which survived a toxic insult was first shown for ionizing radiation and is one of the signs of induced genomic instability. The effect appears to be related to DNA strand breakage or repair but not to the physical break itself. To investigate this and the relationship of lethal mutations or delayed death to other instability endpoints, cultures of immortal but non-transformed human keratinocytes were exposed to a range of environmental mutagens or cytotoxic compounds with different DNA damaging properties.

METHODS

Delayed expression of damage was assessed by scoring a number of endpoints in the progeny of cells which survived exposure and underwent at least 15 population doublings. Endpoints included delayed apoptosis, cloning efficiency of cells in 'healthy' colonies and expression of the apoptosis regulatory proteins bcl-2 and BAX.

RESULTS

The results clearly linked expression of delayed lethal mutations with substances that induced DNA strand breaks. All these substances are known also to induce oxidative stress. The occurrence of delayed damage required a threshold level of toxicity in the initially exposed population, which was remarkably similar for all the effective substances except cadmium. Alkylating agents or microtubule poisons that do not permit repair of DNA damage did not cause any delayed death.

CONCLUSION

It is concluded that delayed cell death may be caused by widespread radical damage to DNA which is either signalled, thereby inducing an apoptotic response, or (mis-)repaired yielding a weak or unstable genome. It is likely that the process may be an important factor in determining the long-term response of populations to 'sublethal' levels of environmental mutagens whose mechanism of action includes DNA strand breakage and repair.

Lung transplantation for cystic fibrosis: effective and durable therapy in a high-risk group

BACKGROUND

The purpose of this study was to review our experience with lung transplantation in patients with end-stage cystic fibrosis.

METHODS

Eight-two patients with cystic fibrosis have undergone bilateral lung transplantation (n=76) or bilateral lower lobe transplantation (n=6) since October 1990.

RESULTS

Actuarial survival for the entire cohort is 79% at 1 year and 57% at 5 years. The development of bronchiolitis obliterans syndrome is the leading cause of death after the first year. Freedom from bronchiolitis obliterans syndrome is 84% at 1 year and 51% at 3 years. Pulmonary function tests improve dramatically in recipients. There was no association between death within 1 year and recipient age, weight, graft ischemic time, cytomegalovirus seronegativity, or the presence of pan-resistant organisms. Similarly, there was no association between the development of bronchiolitis obliterans syndrome within 2 years and ischemic time, number of rejection episodes, cytomegalovirus seronegativity, or the presence of panresistant organisms.

CONCLUSIONS

Despite their poor nutritional status and the presence of multiply resistant organisms, patients with cystic fibrosis can undergo bilateral lung transplantation with acceptable morbidity and mortality.

Tumour marker detection in oesophageal carcinoma

Levels of the tumour markers CEA, CA 19-9, CA 125 and SCC were measured in 58 patients presenting with oesophageal carcinoma and compared with levels in patients with benign oesophageal disease and levels in normal volunteers. CEA and CA 19-9 were significantly increased in the patients with oesophageal cancer, however, individual sensitivity for CEA, CA 19-9, CA 125 and SCC was only 28, 34, 10, and 32%, respectively. The combined sensitivity of all markers was 64% and specificity was 80%. There was no difference in combined tumour marker sensitivity between squamous or adenocarcinomas of the oesophagus. No consistent change in marker levels occurred with treatment, and tumour marker levels could not be significantly correlated with stage of disease or short-term survival. These results indicate that tumour marker sensitivity is too low for oesophageal cancer screening and has poor prognostic significance in those undergoing treatment.

Maternal plasma beta-hCG in early human pregnancy

Beta-human chorionic gonadotrophin (beta-hCG) was assayed twice weekly in plasma from 20 subjects from 4 to 16 weeks gestation; 14 of these were normal. There was an initial rise, a plateau at weeks 7 to 9, and a further rise to a maximum at week 11. Levels then dropped steadily to week 16. There was no significant difference when mean levels were subdivided and calculated according to the subsequent sex of the baby. Of the 6 abnormal subjects, the twin pregnancy initially showed normal levels but at week 11 to 13 these were at least one standard deviation above the mean. The plasma beta-hCG levels of the two subjects who aborted were more than one standard deviation below the mean at week 5. Three subjects treated with progestogen therapy had beta-hCG levels which fluctuated within normal limits. The trends of beta-hCG levels were similar to those of plasma hCG levels in the two subjects who had both assays performed but peak times were different. There was considerable within patient and also patient to patient variation in beta-hCG levels.

The PADL-1.0/2 system for defining and displaying solid objects

PADL (Part and Assembly Description Language) is a language for defining solid objects via constructive solid geometry, i.e. as (regularized) set-theoretical compositions of primitive solid “building blocks”. The current processor for Version 1.0 of the language accepts PADL statements either in batch or in keyboard-interactive mode and produces line drawings of objects on CRT's and plotting devices. A variety of drawing styles is available: dimensioned orthographics, perspectives, section views, interference drawings, etc.

Novel characteristics of the PADL-1.0/2 system include 1) general combinational operators that may be applied to any part defined in PADL, 2) correct handling of “pathologies” that occur when (for example) two objects have partially coincident boundaries, 3) maintenance of consistent multiple representations of the same object, and 4) automatic posting on drawings of dimensions to reflect user-defined geometric relations between features of objects.

This paper provides an overview of both the language and the current processor's capabilities and organization. Detailed discussions of the underlying mathematics, algorithms, and implementation are presented elsewhere.

Arteriography of peripheral hemangiomas

Arteriography has proved useful in evaluation of 17 patients with peripheral soft-tissue hemangiomas (15 benign, 2 malignant) by defining their extent, degree of vascularity, and source of vascular supply and allowing differentiation from arteriovenous malformations. In 11 cases (all benign), moderate fine-caliber hypervascularity with some degree of staining was seen. In 6 (4 benign, 2 malignant) there was marked hypervascularity with coarse, irregular vessels. The coarse or fine hypervascularity which characterizes most benign hemangiomas closely resembles that seen in malignant soft-tissue tumors and may preclude correct diagnosis by angiography alone. However, peripheral hemangiomas frequently exhibit distinctive clinical features which when combined with the arteriographic findings enable the radiologist to identify the lesion.

The use of spermatic cord lymphatics in the relief of surgically created lower extremity edema. A preliminary report of experiments in dogs

When lower extremity lymphedema is not amenable to control by medical methods, attempts to ameliorate the problem surgically have generally been unsatisfactory. The intact testis and spermatic cord provide a potential bridge that may permit communication between the unobstructed lymphatics of the gonadal system and the obstructed lymphatics of the lower extremity. Preliminary experience in male dogs wherein lower extremity lymphedema is first induced surgically and is treated by testicular implantation into the edematous thigh shows that lympholymphatic communications between the lower extremity and the gonadal system may result.

Hemobilia complicating needle liver biopsy. A case report with arteriographic demonstration

Massive hemobilia secondary to a needle liver biopsy developed in a 16-year-old boy with Hodgkin's disease. Cholecystectomy and common bile duct drainage failed to control the condition and the patients bled massively; management of the hemobilia was effected with left hepatic artery ligation. A review of the literature is presented, with a brief discussion of the clinical picture, pathophysiology, diagnosis, and management of this condition.

Therapeutic transluminal arterial embolization for bleeding in the upper part of the gastrointestinal tract

Diagnosis and the treatment of gastrointestinal bleeding by selective and superselective technique and the perfusion of vasopressors have been noted to have significant success. Transluminal embolization of a bleeding site represents an alternative method in patients who represent a poor operative risk and in those in whom vasopressor therapy has failed. The potential risks include intestinal ischemia and vary with the anatomic site.

Tumors of the liver as demonstrated by angiography, scan and laparotomy

One hundred and eighteen patients with various hepatic tumors proved by laparotomy have been analyzed for accuracy and for pitfalls of preoperative studies, namely, physical examination, celiac and superior mesenteric angiography and liver scan. Angiography is correct in detecting a hepatic tumor in 93 per cent and scan, in 87 per cent, overall. When angiography and scan are combined, tumors are detected in 97 per cent of patients. As for specific location and extent of the hepatic tumor to determine its resectability, angiography is correct in 75 and scan in 62 per cent, over-all. Eleven of 39 resectable tumors were deemed nonresectable in preoperative studies. Although angiography and scan are the best available means of diagnosing hepatic tumors, presently, true resectabilty of hepatic tumors can be determined only be exploratory examination.