Point mutation analysis of ras genes in spontaneous and chemically induced C57Bl/10J mouse liver tumours.

The high incidence and profile of ras gene mutations reported in spontaneous and chemically induced liver tumours of the B6C3F1 mouse provides a potential means of determining in vivo genotoxicity and its relevance to carcinogenicity. We analysed spontaneous and chemically induced [with 4-amino-biphenyl (ABP), 2-acetylaminofluorene (AAF) and diethylnitrosamine (DEN)] hepatocellular tumours of the C57Bl/10J mouse for H-ras, K-ras and N-ras gene mutations to see if mutational analysis of the ras genes could be useful for such a determination in this strain. Regions of DNA spanning codons 12, 13 and 61 of the ras genes were amplified from formalin fixed liver tumour sections using the polymerase chain reaction. Mutations were detected using allele specific oligonucleotide probing and confirmed by sequencing. We have found that there are few ras mutations in either spontaneous or chemically induced liver tumours in the C57Bl/10J mouse. Out of 25 spontaneous tumours two contained an A to T transversion and one contained an A to G transition in base 2 of H-ras codon 61 and two contained a G to A transition in base 2 of K-ras codon 13 (the K-ras mutations were only faintly detectable and may be present in a subpopulation of the tumour cells). In the case of the 18 ABP induced tumours one contained a C to A transversion in base 1 of H-ras codon 61, and one contained an A to T transversion in base 2 of H-ras codon 61 and one contained a G to C transversion in base 1 of K-ras codon 13. One C to A transversion in base 1 of H-ras codon 61 was detected out of eight AAF induced tumours. Of the 25 DEN induced tumours, one contained an A to G transition and one contained an A to C transversion in base 2 of H-ras codon 61. The data indicate that at least in hepatocellular tumours of the C57Bl/10J strain and using chronic dosing regimes the ras genes do not represent markers for in vivo genotoxic activity.     

Persistent or recurrent acromegaly. Long-term endocrinologic efficacy and neurologic safety of postsurgical radiation therapy.

As in other clinics, pituitary surgery was definitive treatment in less than 50% of cases of acromegaly treated at one institution over several decades. From 1965 to 1989, 24 acromegalic patients who had noncurative pituitary surgery received radiation therapy at the National Institutes of Health, with a basal human growth hormone level of greater than 5 ng/ml as the criterion for active disease. Using megavoltage irradiation, more than 60% of these patients stabilized at a normal hormonal range, and the overwhelming majority had decreasing growth hormone levels with time. No major side effects of irradiation were encountered except panhypopituitarism of varying degrees. The authors evolved a policy of surgery as the first option, followed by irradiation for patients with postoperative growth hormone levels more than 5 ng/ml.     

Effect of diltiazem on silent myocardial ischemia]

Thirty-four patients with coronary heart disease who had silent myocardiac ischemic episodes as evidenced by long-term ECG monitoring were examined. Silent ST-segment elevations and depressions were encountered 2.7- and 4.9-fold as compared to manifest ones. The fact that the CHD patients had silent ST-segment depressions and/or prolonged high-amplitude silent ST-segment elevations suggests a grave severity of abnormal myocardial processes. There was a reduction in the number, duration of silent ST-segment elevations and depression episodes and in the amplitude of silent ST-segment depressions. This may indirectly indicate that the agent affects predominantly coronary blood flow and coronary vascular tone.     

Depression in patients with cancer

This paper reviews the clinical aspects of depression in cancer from the perspective of prevalence, diagnosis, clinical symptoms, classification and treatment. Clinical trials, reported since 1960, of psychosocial, psychopharmacologic and behavioral interventions are critically evaluated. Therapeutic guidelines are offered for the management of the depressed patients with cancer. Research directions are suggested for the future.     

A programme for treating chemically dependent medical students

Summary. The first American programme for chemically dependent medical students at the University of Tennessee, Memphis is described. The goals of the Aid for the Impaired Medical Student (AIMS) Program are to provide confidential treatment for chemically dependent medical students, to assure that recovering students are able to resume their education, and to protect patients and others from the harm that may be caused by impaired students. The Program is administered by the AIMS Council, consisting of medical professionals and elected student representatives. The Council oversees the management of cases, including investigation of students who may be impaired, intervention when chemical dependency is suspected, diagnostic evaluation, treatment and aftercare, and post-recovery advocacy for students. The Program's experience includes 18 cases of suspected chemical dependency, with four self-referrals and 14 students referred by third parties. Eleven students have been diagnosed as chemically dependent and have completed treatment programmes. Nine have maintained recovery and eight have graduated. One student subsequently relapsed and committed suicide. Obstacles in programme implementation have involved absence of perceived need, the view that chemically dependent students should be dismissed from school, and reluctance of students to report classmates. Resources have included highly respected student representatives, a supportive administration, assistance of the impaired physicians programme, and medical insurance and professional courtesy to defray costs. Although the number treated has been modest, the AIMS Program is an important vehicle for training students regarding chemical dependency and their professional obligations toward impaired colleagues.     

Pathological study of corticospinal-tract degeneration in Friedreich''s ataxia

The pattern of fibre degeneration in the lateral corticospinal tract (LCST) was studied in a case of Friedreich's ataxia (FA). There was preferential involvement of the lateral area of the LCST in the cervical spinal cord. More caudally, the degeneration involved the entire area of the LCST and did not reveal a medial to lateral gradient of involvement. We suggest that this distinctive pattern of tract degeneration is a consequence of the somatotopic organization of the LCST, with the dying-back degeneration preferentially affecting those LCST fibers that extend to the lumbo-sacral spinal cord. This pattern of tract degeneration may be a useful morphological marker of dying-back degeneration in corticospinal tracts.     

Osteochondritis dissecans of the humeral head.

A rare case of osteochondritis dissecans (OCD) occurring in the humeral head is presented. As there are only six available records in the literature concerning OCD in the humeral head, clinical features, treatment, and etiology of OCD involvement of this anatomical part remains unclear. These points are discussed on the basis of the previous cases and ours. Osteochondritis dissecans of the humeral head commonly affects middle-aged and young males rather than females. The prevalent location of involvement is the anterosuperior aspect of the humeral head. We propose that repetitive microtrauma is one of the important causes of OCD in the humeral head. Moreover, we suggest that the most authentic treatment for OCD with a partial detached osteochondral fragment is removal of this fragment and drilling.     

Pharmacokinetics of fluorinated 2-nitroimidazole hypoxic cell radiosensitizers in murine peripheral nervous tissue.

We have previously reported that KU-2285, a 2-nitroimidazole with a fluorinated N1-substituent (-CH2-CF2CONH(CH2)nOH, n = 2), was a promising hypoxic cell radiosensitizer. In this study the pharmacokinetics of KU-2285 and its related compounds (n = 3 and n = 4) were compared with those of etanidazole (a 2-nitroimidazole with an N1-substituent of -CH2CONH(CH2)nOH, n = 2) and its related compounds (n = 3 and n = 4) to assess the effects of incorporation of a CF2 group. The lipophilicity of the fluorinated compounds was higher than that of etanidazole, as measured by the octanol/water partition coefficient. As the number of CH2 groups increased, the lipophilicity of the compounds in both the KU-2285 and etanidazole series increased. The brain tissue levels of the fluorinated compounds were as low as those of the etanidazole derivatives, while the biological half-lives of the fluorinated compounds in peripheral nervous tissues were shorter than those of related non-fluorinated compounds.