Age influences chemotherapy response in astrocytomas

OBJECTIVE

In patients with cerebral astrocytomas treated with nitrosourea-based chemotherapy, to determine whether age is predictive of response, time to progression, survival, or rate of complications.

DESIGN

Retrospective analysis of neuroimaging studies and clinical data.

SETTING

University hospital with a busy neuro-oncology service.

PATIENTS

One hundred forty-eight patients with pathologically confirmed malignant astrocytomas or recurrent astrocytomas.

RESULTS

Partial response occurred in 39% of patients aged < 40 years, in 17% of those aged 40 to 59, and in only 5% of those aged > or = 60 (p < 0.001). Median time to progression after chemotherapy was 23 weeks in patients aged < 60 and 6 weeks in patients aged > or = 60 (p < 0.001). Median survival after chemotherapy was 43 weeks in patients aged < 60 but only 24 weeks in patients aged > or = 60 (p < 0.001). Differences between age groups in response rate, time to progression, and survival persisted with adjustment for tumor grade. The risk of myelosuppressive complications requiring hospitalization was significantly related to age (p = 0.03); such complications occurred in 35% of patients aged > or = 60 and 16% of patients under 60 years.

CONCLUSION

Age is strongly predictive of the likelihood of a response to chemotherapy, time to progression, survival, and risk of myelosuppressive complications. Patients aged > or = 60 have a lower change of benefit and an increased risk of myelosuppressive complications from chemotherapy for astrocytomas compared with younger patients.

Posts, points, and instruments: how to retrieve them, II

This article deals with the removal of metal fragments from root canal spaces. In Part II, two other situations for use of the Masserann kit and the use of ultrasonics will be discussed.

Posts, points, and instruments: how to retrieve them, Part 1

Retrieving metallic objects from teeth and canals produces anxiety, particularly if the dentist retrieving the object placed it there purposely, as in the case of a post, or inadvertently, as in the case of an accidental separation. Part I of this two-part series describes three methods that can be used to retrieve such objects. Case reports are used to exemplify each method. This series cannot turn the experience into an enjoyable one, but it will point out some ways to remove unwanted fragments from root canals.

Protein kinase C modulation of queuine uptake in cultured human fibroblasts

Protein kinase C modulates the activity of a highly specific uptake mechanism for queuine in cultured human fibroblasts. Activators of protein kinase C induce an increased uptake rate for the radiolabeled analog of queuine, rQT3. The protein kinase C inhibitors, H-7, staurosporine and sphingosine all induced a dramatic decrease in the uptake rate of rQT3. This suggests that protein kinase C is tied to efficient cellular uptake of queuine. Uptake is prerequisite to the modification of transfer RNA with queuine. Perturbation of queuine-modified transfer RNA levels has been associated with neoplastic transformation, differentiation and growth control.

Interferon induced inhibition of queuine uptake in cultured human fibroblasts

Interferon inhibits uptake of the radiolabeled queuine analog, rQT3, into cultured human fibroblasts. Simultaneous exposure to 10 nM phorbol-12,13-didecanoate (PDD) potentiates interferon-induced inhibition of rQT3 into cultured fibroblasts. All three major classes of human interferon tested affected uptake similarly, with fibroblast derived beta-interferon being more effective in dose response than gamma or alpha interferons. This suggests that endogenous production of interferon by cultured cells, such as that observed during a low grade viral infection, inhibits queuine uptake and may subsequently lead to a decreased level of queuine modified transfer RNA. Queuine-hypomodified transfer RNA has been implicated in growth control, differentiation and neoplastic transformation.

Schwann cell dysfunction in uraemia

Examination of individual sural nerve fibres revealed segmental demyelination, in 10 out of 12 subjects with uraemia. Peripheral neuropathy was present in only two cases. The complex biochemical changes occurring with dialysis unmask the underlying demyelination in subjects with a latent neuropathy. This would explain the precipitation of a neuropathy in those subjects submitted for repeated dialysis. The possible correlation between creatinine retention, dialysis, and metabolic dysfunction in the Schwann cell system is discussed.