Linkage and mutational analysis of familial Alzheimer disease kindreds for the APP gene region

A large number of familial Alzheimer disease (FAD) kindreds were examined to determine whether mutations in the amyloid precursor protein (APP) gene could be responsible for the disease. Previous studies have identified three mutations at APP codon 717 which are pathogenic for Alzheimer disease (AD). Samples from affected subjects were examined for mutations in exons 16 and 17 of the APP gene. A combination of direct sequencing and single-strand conformational polymorphism analysis was used. Sporadic AD and normal controls were also examined by the same methods. Five sequence variants were identified. One variant at APP codon 693 resulted in a Glu-->Gly change. This is the same codon as the hereditary cerebral hemorrhage with amyloidosis-Dutch type Glu-->Gln mutation. Another single-base change at APP codon 708 did not alter the amino acid encoded at this site. Two point mutations and a 6-bp deletion were identified in the intronic sequences surrounding exon 17. None of the variants could be unambiguously determined to be responsible for FAD. The larger families were also analyzed by testing for linkage of FAD to a highly polymorphic short tandem repeat marker (D21S210) that is tightly linked to APP. Highly negative LOD scores were obtained for the family groups tested, and linkage was formally excluded beyond theta = .10 for the Volga German kindreds, theta = .20 for early-onset non-Volga Germans, and theta = .10 for late-onset families. LOD scores for linkage of FAD to markers centromeric to APP (D21S1/S11, D21S13, and D21S215) were also negative in the three family groups. These studies show that APP mutations account for AD in only a small fraction of FAD kindreds.

The polymorphic locus for glycogen storage disease VI (liver glycogen phosphorylase) maps to chromosome 14

Human liver glycogen phosphorylase deficiency, also known as glycogen storage disease type VI (GSD VI) or Hers disease, is characterized by hepatomegaly and reduced or absent glycogenolytic response to the injection of glucagon. The recently isolated cDNA encoding the liver isozyme of glycogen phosphorylase was used to map the gene and identify restriction-fragment polymorphisms in normal Caucasians as a prerequisite for detecting linked GSD VI abnormalities. Results of restriction-enzyme analysis using a downstream fragment of the liver glycogen phosphorylase cDNA indicated the existence of a single gene copy per haploid genome. Hybridization of this downstream liver phosphorylase probe to dual laser-excited, sorted human chromosomes localized the gene to human chromosome 14. When the downstream probe was tested on genomic DNA cut with seven different restriction enzymes, a single MspI restriction-fragment-length polymorphism (RFLP) was observed in a single individual. In contrast, similar Southern blots performed with an upstream portion of the cDNA encoding liver phosphorylase revealed common RFLPs for four of eight enzymes tested, with minor polymorphic allele frequencies ranging from 33% to 44%. One of the four enzymes (TaqI) revealed two independent polymorphisms. If random distribution of these haplotypes among normal and disease loci, is assumed, approximately 92% of fetuses at risk for Hers disease will be informative when tested with the upstream liver phosphorylase probe.

Intravesical chemotherapy in urinary bladder cancer

Monthly instillation therapy with Adriamycin in a standardized dose of 300 ng/ml/h together with a phosphate buffer at pH 7.4 seems to give satisfactory results in patients with primary bladder carcinoma in situ and in patients with secondary carcinoma in situ of the bladder who have previously received full courses of irradiation. The side-effects are transient and few.

Diarrhea in breast-fed and non-breast-fed infants

During the first year of life a group of babies was prospectively observed for diarrhea and for fecal carriage of heat-labile toxigenic bacteria, with or without colonization factor, and rotavirus. Approximately half of the babies were breast-fed for the first six months of life. There was no difference between groups (breast-fed vs non-breast-fed) in number of babies who had diarrhea during any two-month period. Nor was there any difference between groups in the number of babies who had diarrhea while carrying toxigenic bacteria, with or without colonization factor. Secretory antibody to toxin was found in 37% of colostrum and milk samples. There was a small but insignificant difference in the number of babies who had diarrhea when they carried toxigenic bacteria depending on the presence of antibody in the breast milk they received.

Role of the cellular oxidation-reduction state in methotrexate binding to dihydrofolate reductase and dissociation induced by reduced folates

5-Formyltetrahydrofolate promotes the net dissociation of methotrexate bound to dihydrofolate reductase in the Ehrlich ascites tumor (L. H. Matherly et al., Cancer Res., 43: 2694-2699, 1983). Treatment of Ehrlich tumor cells with glucose or inhibitors of electron transfer stabilized the association of the antifolate with dihydrofolate reductase as reflected by a 2-fold increased fraction of dihydrofolate reductase-bound methotrexate and an abolition of the 5-formyltetrahydrofolate-induced dissociation of the inhibitor-enzyme complex. Glucose and azide were also found to increase the intracellular ratio of reduced nicotinamide adenine dinucleotide phosphate (NADPH) to oxidized nicotinamide adenine dinucleotide phosphate (NADP+) in the tumor approximately 8- and 11-fold, respectively. However, other agents which enhanced the association between methotrexate and its target enzyme were less effective in increasing the intracellular level of NADPH relative to NADP+. Micromolar concentrations of NADPH promoted methotrexate binding to the purified Ehrlich tumor dihydrofolate reductase. Bound methotrexate could be dissociated from the purified enzyme by 5-methyltetrahydrofolate but less readily by 5-formyltetrahydrofolate and only in the presence of reduced levels of NADPH relative to NADP+. The tetraglutamate derivative of 5-methyltetrahydrofolate was even more effective than the underivatized compound in dissociating methotrexate from dihydrofolate reductase. These findings suggest a critical role for the cellular oxidation-reduction state in determining the affinity of dihydrofolate reductase for methotrexate and thus the cellular sensitivity to the antifolate. In addition, the data are consistent with the possibility that dihydrofolate reductase is a key locus for intracellular competitive interactions between reduced folates and methotrexate during leucovorin rescue from the pharmacological effects of the antifolate.

Syme amputation in children: indications, results, and long-term follow-up

Syme amputations are not always effective. Heel pad migration, skin sloughs, and problems with prosthetic fitting may complicate a seemingly simple procedure. We reviewed 69 Syme amputations performed in 62 children at the Los Angeles Shriners Hospital between 1956 and 1980. The major indication was leg length discrepancy, due to either paraxial fibula hemimelia (33 cases) or proximal focal femoral deficiency (19 cases). The average age at amputation was 5.6 years, with an average follow-up of 10.5 years (range 1-25 years). The results were assessed by a combination of chart review, patient recall examinations, and questionnaires. Satisfaction in adulthood was high. Early complications included three skin sloughs and one infection. Late complications included 2 retained os calcis apophyses, 1 exostosis, and 16 cases of heel pad migration. Only one of the heel pad group required revision; prosthetic adjustment resolved the others. Prosthetic knees were often too low because of failure to limit the length of the stump appropriately. Syme amputation should be considered a primary reconstructive procedure, rather than a last resort, in fibula hemimelia and proximal femoral focal deficiency.

Thioguanine administered as a continuous intravenous infusion to pediatric patients is metabolized to the novel metabolite 8-hydroxy-thioguanine

Thiopurine antimetabolites have been in clinical use for more than 40 years, yet the metabolism of thiopurines remains only partially understood. Data from our previous pediatric phase 1 trial of continuous i.v. infusion of thioguanine (CIVI-TG) suggested that TG was eliminated by saturable mechanism, with conversion of the drug to an unknown metabolite. In this study we have identified this metabolite as 8-hydroxy-thioguanine (8-OH-TG). The metabolite coeluted with the 8-OH-TG standard on HPLC and had an identical UV spectrum, with a lambda(max) of 350 nm. On mass spectroscopy, the positive ion, single quad scan of 8-OH-TG yielded a protonated molecular ion at 184 Da and contained diagnostic ions at m/z 167, 156, 142, and 125 Da. Incubation of TG in vitro with partially purified aldehyde oxidase resulted in 8-OH-TG formation. 8-OH-TG is the predominant circulating metabolite found in patients receiving CIVI-TG and is likely generated by the action of aldehyde oxidase.

Poorer prognosis in older patients with endometrial adenocarcinoma

It has been suggested that there are two types of endometrial carcinoma: the first arises in younger women who have hyperestrogenism and has a favorable prognosis and the second occurs in older women, is not associated to estrogen stimulation, and has a poorer prognosis. This study examined the hypothesis that more aggressive carcinomas are found in older patients with no evidence of estrogen stimulation. A retrospective review of all patients (N = 82) with endometrial carcinoma diagnosed and treated at our institution between 1978 and 1990 was undertaken. The following data were analyzed: age at diagnosis, stage, race, histologic type, grade, depth of myometrial invasion, absence or presence of associated hyperplasia, and survival. The mean age of the patients was 64.8 years. Sixty (73%) of the 82 patients were considered estrogen-positive either because of obesity (body mass index > or = 27.3) or the use of unopposed exogenous estrogen. There were no statistically significant differences between estrogen-positive and estrogen-negative patients. Patients > or = 65 years had a 5-year survival of 60% compared with 74% for younger patients. There was a trend toward higher histologic grade among the older patients. Otherwise no statistically significant differences were found between these two groups. Estrogen-negative women > or = 65 years had the worst prognosis with a 5-year survival of 29%. As identified by other investigators, age at diagnosis is a significant indicator of prognosis in patients with endometrial carcinoma. In this series, thin, older (> or = 65 years) women who developed endometrial carcinoma had the worst prognosis.