Pancreatic necrosis: CT manifestations

Pancreatic necrosis is a potential sequela of acute pancreatitis, which pathologically represents a collection of devitalized tissue. Appropriate therapeutic planning requires definition of this irreversibly damaged gland, the presence of which is not consistently diagnosed on the basis of clinical and laboratory data. Over an 18-month period, 22 patients with pancreatic necrosis were studied by one or more computed tomographic (CT) examinations. Retrospective analysis showed the findings to vary with the developmental stage of the necrotizing process. During the acute phase, there was considerable morphologic overlap of necrosis and pancreatic phlegmon. Typical findings were seen in the subacute and chronic stages and included diffuse enlargement of the gland with largely decreased central density. A thick, smooth surrounding rim produced a characteristic saclike configuration. CT-guided aspiration for culture material was performed in four patients with suspected superinfection. Negative gram stain and culture results in two patients allowed surgery to be performed on a more elective basis.     

Synthesis of New 7-Substituted 4-Methylcoumarin Derivatives of Antimicrobial Activity

New cyclic derivatives derived from 4-methyl-7-coumarinyloxyacetic acid hydrazide have been synthesized. Some representative examples were screened for antimicrobial activity.     

Serological assessment of acyclovir treatment of herpes genitalis

Oral acyclovir was given to 60 patients with herpes genitalis--20 experiencing a first attack and 40 with recurrent attacks. All patients were followed up for 1 year. Serial serum samples from the patients as well as from 20 controls were studied to determine the effect of therapy on the immune response to herpes simplex virus (HSV). No toxicity was observed, and very few patients had rather insignificant side effects (e.g., diarrhea). The frequency of recurrence (number of recurrences per year) of genital herpes in acyclovir-treated patients was found significantly lower than in controls. More frequent recurrences were observed in those who had high antibody titer in their early convalescent phase sera than in those without or with a low titer of such antibodies. The antibody titers were reduced in those who received acyclovir as compared with controls. The mean time to seroconversion was longer in the acyclovir-treated group than in controls. Oral acyclovir is thus effective and well tolerated in patients with herpes genitalis. Treatment with acyclovir also diminishes the humoral antibody response to HSV, but it does not prevent recurrence. The effects of acyclovir on the immune response to HSV are discussed.     

Reduction of T2* dephasing in gradient field-echo imaging

Fast gradient field-echo imaging is becoming more common in morphologic studies but is not as widespread as might be hoped because of its susceptibility to local field inhomogeneities that lead to spin dephasing (reducing T2 to T2*) and geometric distortion (frequency misregistration). These problems are manifested in both the in-plane and section-select directions. The authors show that reversal of many of these adverse effects is possible through the acquisition of the gradient field echo in a three- and four-dimensional mode for a fixed echo time (TE), since phase-encoding leads to the capture of the echo within the sampling window. This echo centering is shown to be equivalent to the reduction of dephasing across a pixel. Improvements are also obtained by reducing TE to as short a value as possible.     

Effect of retinoic acid on the clonal growth of childhood myeloid and lymphoid leukemias: a pediatric oncology group study

We have studied the effects of retinoic acid (RA) on bone marrow leukemic cells from children with acute nonlymphocytic leukemia (ANLL) at the time of diagnosis, and on cells from four ALL/lymphoma cell lines (common-ALL, pre-B-ALL, T-ALL, and Burkitt's lymphoma) derived from children with these diseases. Cells were cultured in methylcellulose medium with clinically attainable concentrations (0.25-2.0 microM) of RA for two weeks prior to colony and cluster quantitation. Myeloid progenitor cells (CFU-GM) obtained from children with hematologically normal bone marrows were also cultured with RA. Of 19 patients with ANLL whose cells formed colonies, 16 (84%) were inhibited by RA; three patients showed either increased or unchanged colony numbers with RA. RA had a similar effect on both ANLL cluster and colony growth. RA (1-2 microM) also inhibited colony growth of the pre-B-ALL, common-ALL, and Burkitt's lymphoma lines; the T-ALL line and normal bone marrow CFU-GM were not inhibited. The inhibitory effects of RA on pediatric ANLL bone marrow cells and on some ALL/lymphoma cell lines compared with CFU-GM indicate that RA may be of value in the treatment of these malignancies in children.     

Effects of Recombinant Interferon-Gamma and Interleukin-2 on the Generation of Lymphokine-Activated Killer Cells in Vitro

In order to determine if recombinant interferon-γ (rIFN-γ) can augment the effect of recombinant interleukin-2 (rIL-2) in generating lymphokine-activated killer (LAK) cells, we have incubated normal peripheral blood mononuclear cells (PBMC) with these lymphokines for 3 days and then tested their LAK and natural killer (NK) cell activity. We have found that LAK activity in PBMC from 13 out of 13 normal donors was increased by the combined lymphokines above that due to either lymphokine alone, provided that rIL-2 was present at suboptimal concentration: Optimal levels of rIFN-γ (100 U/ml) were able to enhance the LAK-inducing activity of suboptimal levels (5 U/ml) but not optimal levels (100 U/ml) of rIL-2. NK activity showed a similar response to these concentrations of lymphokines. Activation of LAK/NK cells was accompanied by increases in the percentages of Leu 19⁺ (CD56) cells and TAC⁺ (IL-2-receptor) cells, and in the intensity of TAC antigen expression. These results indicate that combination rIFN-γ and rIL-2 may be more effective in generating LAK/NK cells than rIL-2 alone, particularly with suboptimal concentrations of rIL-2 such as occur during continuous infusion therapy with this agent.     

The relation between hypocholesterolemia and degree of maturation in acute myeloid leukemia

Plasma cholesterol concentrations were determined in 83 acute myeloid leukemia patients. Mean plasma cholesterol concentration (+/- S.D.) at the time of diagnosis was 2.91 mmol/L (+/- 1.13). The percentage of AML patients having hypocholesterolemia was 90.4 per cent. The lowest cholesterol levels were observed in the poorly differentiated FAB subtypes of acute myeloid leukaemia: AMyL(M1) and AMoL(M5a). The results showed that the initial hypocholesterolemia in acute myeloid leukemia is significantly related to the degree of both cytological and cytochemical maturation of leukemic blast cells at diagnosis. The degree of maturation at diagnosis has been shown to be related to prognosis in favour of more differentiated subtypes of acute myeloid leukemia. Also, hypocholesterolemia has been shown in several epidemiological studies to be related to an increased mortality from human cancer. Therefore, the degree of maturation may serve as a link between hypocholesterolemia and the increased mortality from human cancer.