Overproduction and rapid purification of the phosphoenolpyruvate:sugar phosphotransferase system proteins enzyme I, HPr, and Protein IIIGlc of Escherichia coli.

We present methods for the rapid, simple purification of Enzyme I, HPr, and Protein IIIGlc of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system (PTS) using plasmids overproducing gene products. The gene for HPr (ptsH) was cloned into the expression vector pKC30. A simple procedure was devised for the purification to homogeneity of this protein from extracts of heat-induced cells containing pKC30/ptsH recombinant clone. The genes for Enzyme I (ptsI) and Protein IIIGlc (crr) were cloned separately into the expression vector pRE1. Rapid purification procedures were developed for the isolation of homogeneous preparations of these two proteins from extracts of heat-induced cells containing pRE1/ptsI and pRE1/crr recombinants. From about 6 g of cells, these procedures yielded 100, 86, and 50 mg of Enzyme I, HPr, and Protein IIIGlc, respectively. The activity of the proteins purified by these methods was comparable to that of the proteins isolated by previously published less efficient procedures.     

Global convergence properties in multilocus viability selection models: the additive model and the Hardy-Weinberg law

A natural coordinate system is introduced for the analysis of the global stability of the Hardy-Weinberg (HW) polymorphism under the general multilocus additive viability model. A global convergence criterion is developed and used to prove that the HW polymorphism is globally stable when each of the loci is diallelic, provided the loci are overdominant and the multilocus recombination is positive. As a corollary the multilocus Hardy-Weinberg law for neutral selection is derived.Research supported in part by NIH grants GM 39907-01, GM 10452-26 and NSF Grant DMS 86-06244Research supported in part by a US-Israel Binational Science Foundation grant 85-00021 and NIH grant GM 28016     

The role of the electromechanical and reaction-diffusion system of intraneuronal information processing in brain function

The experimental data of previous papers are considered as a basis for the hypothesis about intraneuronal system controlled by cyclic nucleotides and changing the membrane permeability upon creating the generatory potential. This system is suggested to be an extremal molecular regulator in which the price of action per single operation approximates the physical limit. The electro-mechanical intraneuronal system is capable of solving multidimensional physical problems by means of molecular "digital" hypersound holo-gram coded by DNA molecular text which is an image of functions of target search.     

Mutations in the SLC3A1 Transporter Gene in Cystinuria

Cystinuria is an autosomal recessive disease characterized by the development of kidney stones. Guided by the identification of the SLC3A1 amino acid–transport gene on chromosome 2, we recently established genetic linkage of cystinuria to chromosome 2p in 17 families, without evidence for locus heterogeneity. Other authors have independently identified missense mutations in SLC3A1 in cystinuria patients. In this report we describe four additional cystinuria-associated mutations in this gene: a frameshift, a deletion, a transversion inducing a critical amino acid change, and a nonsense mutation. The latter stop codon was found in all of eight Ashkenazi Jewish carrier chromosomes examined. This report brings the number of disease-associated mutations in this gene to 10. We also assess the frequency of these mutations in our 17 cystinuria families.     

XY gonadal dysgenesis and gonadoblastoma: a study in two sisters with a cryptic deletion of the Y chromosome involving the SRY gene

This paper reports a case of XY gonadal dysgenesis in two sisters. Both patients presented an eunochoid female phenotype with normal external genitalia. At laparotomy, the elder sister was found to have bilateral gonadoblastoma. Cytogenetic studies, which included G and C banding and in situ hybridization, showed that the patients had an apparently normal 46, XY karyotype. PCR analyses revealed absence of the conserved portion (HMG box) of the SRY gene and of the Y chromosome pseudoautosomal boundary region sequence in both patients. The presence of the ZFY sequence was detected by Southern hybridization in the two affected sisters. The patients' father (46, XY, no mosaicism detected in peripheral blood lymphocytes) was positive for SRY and ZFY sequences. The occurrence of gonadoblastoma is discussed in terms of the genetic factors that may lead to tumor development.     

Ectopic ACTH syndrome

Ectopic ACTH syndrome represents a cancer-induced amplification of a property [proopiomelanocortin (POMC) peptides production] normally present in the cells from which the cancer originated but with aberrant posttranslational processing of POMC resulting in a greatly elevated secretion of ACTH precursors. The classic ectopic ACTH-producing tumors described in the 1960s were highly malignant but more recently slowly growing tumors such as carcinoids are reported with increasing frequency. Clinical features of patients with ectopic ACTH were analyzed, including biochemical abnormalities, plasma ACTH, cortisol and urinary steroids. Dynamic tests such as high-dose dexamethasone suppression, metyrapone and ovine-CRH (oCRH) stimulation were explored, as well as inferior petrosal sinus ACTH sampling before and after oCRH. Among the tumor markers examined, elevation of ACTH precursors was uniformly present followed by increased output of calcitonin, gut hormones, oncofetal and placental hormones in decreasing order. Since more than 90% of ectopic ACTH tumors are neuroendocrine in nature exhibiting APUD characteristics, their 2 markers, neuron-specific enolase and chromogranins are very useful. The imaging procedures for localization of the tumor ranged from chest X-rays to computed tomography and magnetic resonance of the chest and abdomen. Abdominal ultrasonography was also useful. Finally somatostatin receptor scintigraphy permitted demonstration of unrecognized tumors and/or metastases, even when the tumors were occult. The ACTH content, immunostaining for APUD markers and altered POMC processing were evaluated in ectopic tumors and/or metastases. Occult ectopic ACTH syndrome of more than 4–6 months of symptoms without the emergence of an obvious source was reviewed. Since the tumors are often clinically and biochemically undistinguishable from pituitary-dependent Cushing's disease, inferior petrosal sinus sampling for ACTH after oCRH stimulation established the diagnosis in over 90% of the cases. 60% of the occult tumors were thoracic carcinoids (3/4 bronchial carcinoids), followed by small cell lung cancer and pancreatic neuroendocrine tumors. In 12% the primary etiology was not detected. The rare syndrome of ectopic CRH syndrome (6 published cases) leading to excessive stimulation of the pituitary which became hyperplastic and secreted excessive amounts of ACTH is discussed. Finally, the 12 published cases and 1 unreported patient with ectopic CRH-ACTH tumors were reviewed, the majority being metastatic small cell lung carcinomas, bronchial and thymic carcinoids.     

Tuberous sclerosis with pulmonary involvement.

Pulmonary tuberous sclerosis produced interstitial disease in a woman with normal-sized lungs; numerous hemosiderin-laden macrophages were found in the fluid obtained through bronchoalveolar lavage. The pathological changes seen in the lungs were identical to those of pulmonary lymphangiomyomatosis, in which the constellation of clinical signs usually found in tuberous sclerosis is absent. The two conditions are sufficiently similar in clinical presentation, pathological changes and prognosis to be considered variants of the same disease. The recent findings of progestin receptors in lung tissue from patients with pulmonary lymphangiomyomatosis will likely direct future management towards hormonal manipulation.