Testing shelled corn for aflatoxin, Part II: modeling the observed distribution of aflatoxin test results

The suitability of several theoretical distributions to predict the observed distribution of aflatoxin test results in shelled corn was investigated. Fifteen positively skewed theoretical distributions were each fitted to 18 empirical distributions of aflatoxin test results for shelled corn. The compound gamma distribution was selected to model aflatoxin test results for shelled corn. The method of moments technique was chosen to estimate the parameters of the compound gamma distribution. Mathematical expressions were developed to calculate the parameters of the compound gamma distribution for any lot aflatoxin concentration and test procedure. Observed acceptance probabilities were compared to operating characteristic curves predicted from the compound gamma distribution, and all 18 observed acceptance probabilities were found to lie within a 95% confidence band. The parameters of compound gamma were used to calculate the fraction of aflatoxin-contaminated kernels in contaminated lots. At 20 ppb, it was estimated that about 6 in 10,000 kernels are contaminated.

Testing shelled corn for aflatoxin, Part III: evaluating the performance of aflatoxin sampling plans

The effects of changes in sample size and/or sample acceptance level on the performance of aflatoxin sampling plans for shelled corn were investigated. Six sampling plans were evaluated for a range of sample sizes and sample acceptance levels. For a given sample size, decreasing the sample acceptance level decreases the percentage of lots accepted while increasing the percentage of lots rejected at all aflatoxin concentrations, and decreases the average aflatoxin concentration in lots accepted and lots rejected. For a given sample size where the sample acceptance level decreases relative to a fixed regulatory guideline, the number of false positives increases and the number of false negatives decreases. For a given sample size where the sample acceptance level increases relative to a fixed regulatory guideline, the number of false positives decreases and the number of false negatives increases. For a given sample acceptance level, increasing the sample size increases the percentage of lots accepted at concentrations below the regulatory guideline while increasing the percentage of lots rejected at concentrations above the regulatory guideline, and decreases the average aflatoxin concentration in the lots accepted while increasing the average aflatoxin concentration in the rejected lots. For a given sample acceptance level that equals the regulatory guideline, increasing the sample size decreases misclassification of lots, both false positives and false negatives.

Testing shelled corn for aflatoxin, Part I: estimation of variance components

The variability associated with testing lots of shelled corn for aflatoxin was investigated. Eighteen lots of shelled corn were tested for aflatoxin contamination. The total variance associated with testing shelled corn was estimated and partitioned into sampling, sample preparation, and analytical variances. All variances increased as aflatoxin concentration increased. With the use of regression analysis, mathematical expressions were developed to model the relationship between aflatoxin concentration and the total, sampling, sample preparation, and analytical variances. The expressions for these relationships were used to estimate the variance for any sample size, subsample size, and number of analyses for a specific aflatoxin concentration. Test results on a lot with 20 parts per billion aflatoxin using a 1.13 kg sample, a Romer mill, 50 g subsamples, and liquid chromatographic analysis showed that the total, sampling, sample preparation, and analytical variances were 274.9 (CV = 82.9%), 214.0 (CV = 73.1 %), 56.3 (CV = 37.5%), and 4.6 (CV = 10.7%), respectively. The percentage of the total variance for sampling, sample preparation, and analytical was 77.8, 20.5, and 1.7, respectively.

Diagnosis and follow-up of acute promyelocytic leukemia by detection of PML-RAR alpha gene rearrangement

BACKGROUND

Rapid and accurate diagnosis of acute promyelocytic leukemia (APL) is essential for management of the disease, as all-trans retinoic acid (ATRA) therapy only induces complete remission in patients whose leukemic cells harbor a t(15;17) translocation, resulting in promyelocytic-retinoic acid receptor alpha (PML-RAR alpha) fusion transcripts. Moreover, a positive reverse transcriptase-polymerase chain reaction (RT-PCR) of PML-RAR alpha is reported to be a sensitive predictor of relapse in APL. This prompted us to use RT-PCR for rapid diagnosis and monitoring of minimal residual disease in APL patients.

METHODS

A nested RT-PCR technique was applied to detect the unique PML-RAR alpha fusion transcript in 13 APL patients. The test was applied to help clarify the diagnosis and monitor minimal residual disease after treatment.

RESULTS

All 13 APL patients had a positive test result: five patients with the S-form, seven patients with the L-form and one patient with the V-form of mRNA fusion transcripts. Minimal residual disease was prospectively monitored using this technique in six patients. Although in clinical remission, all four patients treated with ATRA alone were persistently PCR positive. Of the six patients receiving various forms of consolidation chemotherapy, one was persistently PCR positive while in remission and relapsed four months after the positive PCR test. Five patients were PCR negative. One of the five negative patients relapsed six months after a negative PCR test. The other four patients remained in remission, with a follow-up period of 25 to 46 months after the negative test. PCR was performed in two patients who had been in continuous remission for 3.5 and seven years, respectively. They both had negative PCR tests.

CONCLUSIONS

Nested RT-PCR is valuable for confirming the diagnosis of APL and in monitoring minimal residual disease. However, we found that negative test cannot absolutely exclude the possibility of future relapse.

Bilateral choroidal metastases as the initial presentation of a small breast carcinoma: a case report

Most ocular tumors metastasize from systemic origins in breast carcinoma in females, and bronchial carcinoma in males. Here, we report a case of choroidal carcinoma metastasis from the breast with visual problems being the only initial manifestations. In this case, both eyes were involved at almost the same time, with initial manifestation of blurred vision which progressed to complete visual loss. At first, the patient was diagnosed with malignant melanoma, and enucleation of the right eye was performed in another hospital. However, the tumor had already metastasized rapidly to numerous organs, including the lungs, brain and bone, although it had not affected the liver. Clinical presentations were, therefore, not compatible with those of malignant melanoma, which has usually been reported to metastasize to the liver. Persistent hypercalcemia and raised carcinoembryonic antigen (CEA) concentrations prompted investigations into the possibility of systemic malignancy. A very small breast nodule was finally located by thorough physical examination, and a lumpectomy was performed. A detailed review of the histopathology showed the tumors from the breast and the right eye to have the same origin. Simultaneous bilateral choroidal metastases from other malignancies is not uncommon; however, it is quite rare for breast carcinoma to present with visual problems as a first manifestation. Detailed history taking and physical examination are therefore essential when searching for a primary tumor, so that appropriate therapy can be given earlier.

Malignant lymphomas of sinonasal region, including cases of polymorphic reticulosis: a retrospective clinicopathologic analysis of 34 cases

BACKGROUND

Lymphomas occurring in nasal cavities and paranasal sinuses are uncommon neoplasms in Western, but are reported to be higher in Oriental, countries. A retrospective study was performed to analyze the clinical and pathological characteristics of sinonasal lymphomas/polymorphic reticulosis at Taichung Veterans General Hospital during a 14-year period.

METHODS

At Taichung Veterans General Hospital, 37 patients with sinonasal lymphomas (including three patients with polymorphic reticulosis) were seen from November 1982 through September 1996. Excluding three patients without sufficient data, a total of 34 patients with their clinical records were reviewed. Clinical information regarding characteristics of the tumors, histological studies, treatment modalities and follow-up was collected for analysis.

RESULTS

The 34 patients who underwent review showed a male-to-female ratio of 2.1:1. Median age was 60 years (range 13-83 years). The most common symptoms were nasal obstruction, nasal discharge/rhinorrhea and epistaxis. Median duration of symptoms at the time of diagnosis was two months. The most frequently involved sites were nasal cavities (right more than left side). There were 31 non-Hodgkin's lymphomas and three polymorphic reticuloses. The pathological classifications revealed 13 diffuse large cell lymphomas, 14 diffuse mixed small and large cell lymphomas and four pleomorphic T-cell lymphomas. Of the 21 adequately staged patients, 13 patients were in stage I; four, stage II; two, stage III and two, stage IV. The immunophenotypic study was performed in 20 patients. Eighteen (90%) of them were T-cell lymphomas and only two cases (10%) derived from B-cell. Though approach to therapy and follow-up periods varied during the time period covered by this study, the differences in survival according to treatment modalities were not statistically significant. The follow-up period ranged from 9 days to 130 months. The mean survival was 84.2 months. The overall five-year survival rate was 63%.

CONCLUSIONS

The majority of the cases here were T-cell lymphomas. Most histologic grading by Working formulation belonged to the intermediate grade. Optimal treatment for such a group of patients still has no consensus, but adequate local control is important. If diagnosed and treated early, primary sinonasal lymphomas can be associated with a favorable outcome even with local treatment alone.

Pharmaceutical services in the United States Air Force

The status of pharmaceutical services in the United States Air Force medical service is described. Air Force pharmacy is adopting new programs, staffing standards, inventory methods, and roles for pharmacists and technicians. One of the most visible changes is TRICARE, an interservice program that provides improved access to care. Many Air Force medical treatment facilities have been closed; prescription mail-out programs and networks of community pharmacies are filling the gap. The Air Force pharmacy team consists of more than 1300 pharmacists and technicians. Air Force pharmacists are military officers first. Great emphasis is placed on medical readiness training and continuing education. Some Air Force pharmacies are very small outpatient operations filling fewer than 300 prescriptions per day; others fill well over 4000. Many hospitals are being considered for more outpatient-focused operations. Because of anticipated minor reductions in pharmacist staffing, Air Force pharmacists will have to maximize efficiencies to maintain or improve current levels of service. More and better patient information will be provided and distributive processes streamlined. A greater role for technicians is anticipated. The future includes pharmacists serving in a wide variety of leadership and staff positions, improving the use of computers, and incorporating new technologies. Air Force pharmacy is changing to ensure uninterrupted fulfillment of its responsibilities.

Spontaneous remission in acute myelogenous leukemia: a case report

A 62-year-old woman with hypocellular acute myelogenous leukemia experienced spontaneous remission after repeated episodes of severe infections. Transient surge of profuse blasts in the peripheral blood was observed prior to the occurrence of spontaneous remission. The duration of the spontaneous remission was relatively short, and the disease relapsed five months later. A second complete remission was achieved after chemotherapy with low-dose cytosine arabinoside. The patient finally died of relapsed leukemia after a second remission of three year duration. Possible mechanisms implicated in the occurrence of spontaneous remission in this patient are discussed.

Prenatal and molecular diagnosis of hemophilia B

Prenatal diagnosis was carried out on a woman who had previously given birth to a son with a spontaneous mutation of C-->T transition at nt 31133 of the factor IX (F.IX) gene. The diagnosis was performed on chorionic villi sampling by the method of amplification-created restriction site (ACRS). It revealed a female fetus with a normal F.IX gene, as confirmed by DNA sequencing after delivery. Meanwhile, a survey using the ACRS method to evaluate the inheritance of 63 individuals from 8 hemophilia B families was done. A different single-point mutation in each family was proved by DNA sequencing. One individual had a mutation with a naturally-created restriction site. In each of the remaining patients, we were able to show an enzyme-cutting site in their DNA amplification product for ACRS with the designed mutagenesis primers. All patients and carriers could be diagnosed accurately by comparing ACRS results with clinical and laboratory findings. There were new novel mutations among the patients.

Three novel and one C31133T (Arg-338-->Stop) mutations of antihemophilic factor IX gene detected in Taiwan

BACKGROUND

Hemophilia-B is caused by mutation of the coagulation factor IX (F.IX) gene. The gene is about 34 kilobases in length and contains 8 exons ranging from 25 to 548 base pairs. There is no common mutation pattern of this gene in any population as there is in thalassemia. The hope is to localize the mutations in patients for use in making rapid familial surveys and for prenatal diagnoses.

METHODS

Diagnoses for a male patient with a newly-discovered mutation in Taiwan and three others with different novel mutations of F.IX gene were made from the results of prothrombin time (PT), activated partial thromboplastin time (APTT), assay of coagulation factors activity and factor IX antigen (F.IX:Ag) and also by assay of its inhibitor. The polymerase-chain-reaction (PCR)-based direct sequencing method was applied to evaluate all of the 8 exons and their flanking regions of F.IX gene for these patients.

RESULTS

The four male patients are all severe hemophilia-B. In the three patients with novel mutation of F.IX gene, two have a very low F.IX:Ag of less than 1% and one has 73%, but no one has any inhibitor. One of the four mutations is A to C transversion at nucleotide (nt) 10458 resulting in tyrosine (69) to serine change in epidermal growth factor (EGF) type B domain. Although the F.IX:Ag is present, the F.IX activity (F.IX:C) is markedly deficit owing to the change of beta-hydroxylase recognition site. Another two have mutations at the splicing junctions. They are G to C transversion at nt 118, i.e. the first base of IVS-1 splicing donor, and G to T transversion at nt 17668, the last base of IVS-4 splicing recipient. These mutations may cause splicing failure and subsequently result in deficiency of both F.IX activity and antigen. The other mutation that has never previously presented in this country is a C to T transition (arginine-338 to stop) at nt 31133 that results in early termination of translation.

CONCLUSIONS

The G to C mutation at nt 118 creates an Alu I restriction site and the C to T mutation at nt 31133 abolishes a Taq I site. Therefore, familial survey and rapid prenatal diagnosis for these patients by PCR-based direct sequencing method or by the restriction of enzyme cutting method pointing at the known mutation sites are certainly possible to achieve in our patients.

Parameters governing steam sterilization of deadlegs

Use of saturated steam for sterilization-in-place (SIP) is limited by factors effecting displacement of air from deadlegs. Effects of tube diameter, length, orientation and position within a deadleg were quantitatively studied by examining temperature profiles and rates of kill of Bacillus stearothermophilus spores. Tube diameter had the greatest effect on sterilization. For small diameter tubes, 0.4 cm inside diameter (ID), air displacement was minimal and due mainly to diffusion. 8.8 cm long tubes with 0.4 cm IDs could not be sterilized at 121 degrees C. As tube diameter was increased and buoyant driven convective flow became dominant over viscous forces, sterilization was achieved and tube orientation became critical. Sterilization time, as defined by a twelve log reduction in spore population, was 75 minutes in a 19.0 cm long vertical tube with 1.7 cm ID, whereas 167 minutes were required for an 8.8 cm long tube with 1.0 cm ID. For 8.8 cm long tubes, only the 1.7 cm ID tube could be sterilized when orientated 5 degrees above horizontal. Data show that length to diameter ratios, L/Ds, do not provide a general guideline which can be used to predict sterilization. In the absence of steam bleeders, equipment should be designed to assure strong buoyancy driven convective flow to assure adequate air removal. This requires elimination of small diameter deadlegs (0.4 cm ID and less) and vertical positioning of deadlegs.

Isolated extramedullary relapse of acute lymphoblastic leukemia presenting as an intraspinal mass

Leptomeningeal relapse is a common finding in acute lymphoblastic leukemia (ALL), but a solid intraspinal mass with cord compression as the sole site of extramedullary relapse is unusual. We report an adult patient with ALL, after 2 years of complete remission, who developed a spinal cord compression due to an intraspinal mass as a first manifestation of extramedullary relapse. Manifestation of first relapse in ALL presenting as an intraspinal mass is rare and may be added to other unusual extramedullary sites of relapse.