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J A Holt

Publications and source records attributed to J A Holt.

At least 37 records · Page 2Linked to original sources
PubMed1995

Some characteristics of the glutathione cycle revealed by ionising and non-ionising electromagnetic radiation.

The cyclic reaction of GSH-->GSSG-->GSH (designated R(exp) or R(e)) obeys the three specific features of life by producing energy in exponential quantities relative to time, is in effect irreversible and is inherited from generation to generation. In multicellular life, this reaction produces the energy for mitosis and is kept in controlled inactivity until needed to maintain perfection of form and function by energising mitosis. The immediate control of Re appears to be feedback process-dependent on the concentration of GSSG. Ultra high-frequency electromagnetic radiation of 434 MHz (UHF) will change Re from inactive to active and, in so doing, it causes resonance and/or fluorescence of the glutathione cycle which changes its radiosensitivity. Re is the primary direct target of ionising radiation and produces the energy for mitosis. Clinical observations suggest that, in the normal cell, Re is inactive and is not killed by 3 x 2700 rads or 6 x 1650 rads yet, when active, its sensitivity value (DO) is approximately 160 rads. Using the standard radiobiological equation of response to ionising radiation, it can be deduced that radiosensitive cancers have two or three Re units active per cell and radioresistance increases in proportion to the number of potentially active Re units per cell. Re appears to be the main cause of cancers' increased conductivity of electricity compared with normal tissue. In cancer therapy, UHF is the best radiosensitiser ever discovered (up to two or more decades). Re is also intelligent compared with non-exponential reactions but cannot be the basis of intellectual brain functions which must be based on non-electrical chemical processes.

Adolescent↗
PubMed1995

T-->A transversion 11 bp from a splice acceptor site in the human gene for steroidogenic acute regulatory protein causes congenital lipoid adrenal hyperplasia.

Congenial lipoid adrenal hyperplasia (lipoid CAH) is the most severe form of CAH. Affected individuals can make no adrenal or gonadal steroids. All affected individuals are phenotypic females irrespective of gonadal sex, and frequently die in infancy if mineralocorticoid and glucocorticoid replacements are not instituted. Recent data implicate the steroidogenic acute regulatory (StAR) protein in this disorder. We now describe a 46,XY patient of Vietnamese ancestry with lipoid CAH who had a somewhat milder form of the disease. Diagnosis was at 10 weeks of age, and low levels of plasma progesterone, corticosterone, 180H-corticosterone and androstenedione were detectable. Testicular RNA for StAR was reverse transcribed, amplified, cloned and sequenced, revealing a 185 bp deletion corresponding to all of exon 5. The corresponding mRNA did not encode active protein in transfected cells. Cloned genomic DNA from the patient revealed only a T-->A transversion in intron 4,11 bp from the splice acceptor site of exon 5. This transversion destroys an NcoI site; digestion of PCR-amplified genomic DNA from the patient and both parents confirmed that the patient was homozygous and the parents were heterozygous. Expression vectors for StAR minigenes were constructed containing all StAR exons plus introns 4, 5 and 6 either with or without the T-->A mutation in intron 4. RNase protection assays showed that expression of the vector with normal intron 4 yielded correctly spliced StAR mRNA in transfected COS-1 cells, while most, but not all StAR mRNA from the vector with the T-->A transversion in intron 4 was abnormally spliced. RNase protection of the patient's testicular RNA confirmed that most, but not all StAR mRNA was similarly spliced abnormally. Splicing errors appear to be a rare cause of genetic diseases, but subtle intronic mutations may be missed when genomic DNA is the only material available for study. The low level of normal StAR mRNA produced may account for the later clinical presentation and low levels of steroid hormones detected in this patient.

Adrenal Hyperplasia, Congenital↗
PubMed1995

Efficiency of screening procedures for assigning levels of the Stanford Achievement Test (eighth edition) to students who are deaf or hard of hearing.

Assignment to an appropriate test level is crucial to the validity of standardized test scores. The present study examined the efficiency of the Reading Screening Tests and Mathematics Screening Tests developed by the Center for Assessment and Demographic Studies (CADS) of Gallaudet University for assigning levels of the Stanford Achievement Test, 8th edition (SAT-8), to deaf and hard-of-hearing students. Data were collected from programs participating in the 1990 test standardization with this population. It was found that while the screening procedures provide a credible means of assigning test levels, they are more effective for the SAT-8's Reading Comprehension, Total Language, Mathematics Computation, and Mathematics Applications subtests than for the Spelling and Concepts of Number subtests. This article concludes with recommendations in regard to individual subtest assignments.

Deafness↗
PubMed1994

The structure of the human sterol carrier protein X/sterol carrier protein 2 gene (SCP2).

Sterol carrier protein X (SCPx) is a 58-kDa protein that is localized to peroxisomes. The amino acid sequence of the protein suggests that SCPx may function as a thiolase. The gene encoding SCPx also codes for a 15.3-kDa protein called sterol carrier protein 2 (SCP2). Here we report the structure of this gene (SCP2), which spans approximately 80 kb and consists of 16 exons and 15 introns. Multiple transcription start sites were identified. The 5' flanking region has characteristics of other peroxisomal protein promoters, which include the absence of a TATA box and a G+C-enriched region containing several reverse GC boxes.

Acetyl-CoA C-Acetyltransferase↗
PubMed1994

CA-125 in peritoneal fluid from patients with nonmalignant gynecologic disorders.

To assess the diagnostic value of measuring CA-125 levels in peritoneal fluid from women with nonmalignant gynecologic disorders, we determined CA-125 levels in peritoneal fluid and in serum collected simultaneously from 46 women undergoing gynecologic surgery. Patients with benign ovarian disease, non-ovarian gynecologic pathology and severe endometriosis had, on average, higher CA-125 levels in peritoneal fluid than did patients with a normal pelvis and those with mild endometriosis. There was no obvious correlation between peritoneal fluid and serum levels of CA-125. Our data show that (1) measurement of serum CA-125 levels is not useful for distinguishing between different benign gynecologic disorders, and (2) levels of CA-125 in peritoneal fluid in benign gynecologic disorders are comparable to the reported lower range of levels observed in women with intraperitoneal malignancies.

Aftercare↗
PubMed1993

Rapid vascular escape of arterially injected 16 alpha-radioiodo,17 beta-estradiol.

PURPOSE: We undertook this study because confirmation of a rapid vascular escape and slow release back into the circulatory system suggests that arterial injection of radiohalogenated steroid receptor ligands might provide an efficacious route of administration for imaging or treatment of receptor-rich malignant tumors in peripheral tissues. METHODS AND MATERIALS: We injected radiolabeled 16 alpha-iodo,17 beta-estradiol ([I]-E), an estrogen receptor ligand, into the femoral artery of swine in a solution that contained [125I]-E in a known ratio to [99mTc]-labeled red blood cells. Fractions of femoral venous blood were collected at short intervals during 10 min. We looked for changes in the ratio of the radiolabels. [99mTc]-labeled red blood cells are known to remain in the vascular system for an hour or more. RESULTS: After passage of the injectate through the capillary bed of the swine leg, a dramatic decrease of the initial 125I:99mTc ratio to only 10% was observed in the femoral venous blood. This ratio increased gradually during the next 10 min to approximately 30% of that in the injectate, indicating that a significant portion (approximately 90%) of the [125I]-E was initially trapped in the limb and then slowly re-entered the vascular system. To obtain visual confirmation of the rapid vascular escape of iodo-estrogen, we injected either an imageable form of [I]-E (123I]-E) or [99mTc]-labeled red blood cells into the dorsal aorta of superovulated rabbits, whose smaller size allowed whole-body imaging. The biodistributions of these radiopharmaceuticals were surveyed continuously by real-time planar gamma imaging. Within 2 min after the injection of [123I]-E, the outlines of the circulatory system were entirely lost; however, some estrogen receptor-rich tissues (the ovaries) as well as some non-target tissues, for example, the lower leg extremities, yielded well-defined images. In contrast, after intra-arterial injection of [99mTc]-labeled red blood cells, the circulatory system remained sharply defined for the duration of the study (40 min). CONCLUSION: A large fraction of [I]-E escapes from the vascular system during the first pass through an organ or limb, without regard to the estrogen receptor content of the tissue.

Animals↗
PubMed1993

Breaks in DNA accompany estrogen-receptor-mediated cytotoxicity from 16 alpha[125I]iodo-17 beta-estradiol.

Strategies for diagnosis and therapy in which sex steroid receptor ligands serve as carriers for radionuclides are attractive because a high incidence of carcinomas of the female genital tract and the breast that are seen clinically have an abundant expression of one or more of the receptor proteins. A radiohalogenated estrogen receptor (ER) ligand, 16 alpha-[123I]iodo-17 beta-estradiol [123I]E, has met clinical criteria for receptor-mediated diagnostic imaging. Its [125]I-labeled sister nuclide derivative [125I]E decays by orbital electron capture with emission of very-low-energy (Auger) electrons, which gives this latter radiohalogen the potential to serve in pharmaceuticals for radiotherapy; as examples, [125I]deoxyuridine, when incorporated into the DNA molecule, or [125I]E, when bound to the receptor within ER-rich tumor cells, are both cytotoxic in vitro. Whereas the mechanisms and subcellular changes that accompany the cytotoxicity from [125I]deoxyuridine are well documented in the form of aberrations and breaks in the cellular DNA, the effects at the subcellular level causing the cytotoxicity of the sex steroid receptor ligand [125I]E have not been characterized and are the focus of our study. We found that in a standard colony-forming assay the addition of [125I]E to the cultures decreased the survival rate of ER-positive MCF-7 cells in a dose-dependent manner. The decreased survival rate was prevented by the addition of competing excess radioinert ER ligand (diethylstilbestrol); [125I]E did not reduce survival in ER-negative MCF-7 cells. The [125I]E-induced and ER-mediated cytotoxicity was accompanied by aberrations in the DNA components of the nuclei of the cells. These included chromatid and chromosome breaks, gaps, and tri-radial chromosome formation. Our findings add plausibility and credence to the notion that the cytotoxicity imparted by Auger-electron-emitting radioligands for sex steroid receptors is in part attributable to radiodecay that causes double-stranded breakage of DNA.

Chromosomes↗
PubMed1993

The glutathione cycle is the creative reaction of life and cancer. Cancer causes oncogenes and not vice versa.

Life is definable as a chemical reaction which obeys exponential growth and dies if reversed. Such a reaction must be the commencement of all life so that every evolved form of it inherits these characteristics. As no single reaction known has these two features, life must be a combination of two or more reactions which whilst obeying all the classical laws of physics and chemistry assume an exponential form and effectively act as being irreversible. The reactions of glutathione--oxidation and reduction--when combined in sequence as a cyclical process fulfill these criteria. The cyclic changes of glutathione from reduced to oxidised to reduced forms must therefore be the reaction which creates life and is responsible for cancer's growth. 434 mHz electromagnetic radiation stimulates cancer growth rate by forcing this cycle into activity. Proof of this hypothesis is the long-term control of cancer in 11 patients treated with oxidised glutathione and 434 mHz radiation. Genetic material does not contain any energy system with exponential form, neither is it self-replicating. Genetic material will only reproduce if placed within an immortal cell in which all controls of the glutathione system have been lost, as in a cancer cell. Oncogenes must be the product of cancer and not the reverse.

Adult↗
PubMed1992

Correlation of cervicovaginal fluid volume with serum estradiol levels and total follicular volume during human gonadotropin stimulation.

During the normal menstrual cycle the volume of cervicovaginal fluid (CVF), as determined by the patient at home using a simple volumetric aspirating pipette, increases significantly over several days prior to the luteinizing hormone (LH) surge and decreases characteristically shortly after ovulation. The present study was undertaken to test the hypothesis that self-determined measurements of CVF volume would correlate positively with serum estradiol (E2) levels and with total follicular volume (TFV) in cycles stimulated with exogenous gonadotropins. Consequently, 20 infertility patients, undergoing human menopausal gonadotropin (hMG)-stimulated cycles, were asked to measure daily CVF. Routine serum E2 determinations and vaginal follicular ultrasound studies were performed up to and including the day of human chorionic gonadotropin (hCG) administration (designated day 0). The mean daily CVF volume (+/- SD) increased from 0.1 +/- 0.01 ml on day -6 to 0.7 +/- 0.40 ml on day -1 and then decreased to 0.6 +/- 0.40 ml on day 0. On day 0, 7 of 20 cycles (35%) demonstrated a decrease in CVF, which ranged from 0.1 to 1.0 ml (mean, 0.42 ml). The mean daily CVF correlated positively (correlation coefficient = r) with the mean daily serum E2 (r = 0.89) and with the mean daily TFV (r = 0.88). The mean daily correlation of TFV for E2 was r = 0.98. The correlation between CVF and E2 of individuals ranged from r = 0.38 to r = 0.99 and the correlation between CVF and TFV ranged from r = 0.12 to r = 1.0, while the individual correlations of E2 to TFV ranged from r = 0.60 to r = 0.99.(ABSTRACT TRUNCATED AT 250 WORDS)

Cervix Mucus↗
PubMed1992

Detection of the HER-2/neu proto-oncogene protein p185erbB2 by a novel monoclonal antibody (MAB-145ww) in breast cancer membranes from oestrogen and progesterone receptor assays.

Amplification of the proto-oncogene HER-2/neu and/or overexpression of the transmembrane protein p185erbB2 that it encodes occur in approximately 30% of human breast and gynaecological cancers seen clinically and are strongly associated with an unfavourable outcome. We report on the use of a new monoclonal antibody (Mab-145ww) together with immunoblotting for detection of p185erbB2 in membranes that remain after routine processing of breast cancer tissue for steroid receptor assays. Human breast cancer cell lines SKBR3 and MCF-7 were used as high and low controls, respectively, for p185erbB2 expression. Mab-145ww was detected p185erbB2 in more than half of the breast cancer specimens; the expression was intense in SKBR3 cells, but only faint in MCF-7 cells. These results demonstrate that routine processing of cancer tissue for steroid receptor status can include providing a preparation with which to assess p185erbB2 expression and, thus, can provide information potentially useful for the clinical management of individual cancer patients.

Antibodies, Monoclonal↗
PubMed1992

Intracellular actions of steroid hormones and their therapeutic value, including the potential of radiohalosteroids against ovarian cancer.

The biological activities of steroid hormones are effected via intracellular receptors. The receptors are part of a ligand-activated family of transcription regulator proteins that are critical for steroid-regulated cell differentiation. With recombinant cDNA technology, yeast and cultured animal cells can be made to express mammalian cDNA steroid receptors from cDNA clones that contain deletions and substitutions. Among the leading problems addressed in these models is the characterization of sequences that promote association or interaction with other transcription regulating molecules, including oncogene products. Recently it has been found that heat shock proteins may serve not only to stabilize the receptor proteins but also to precondition the activation imparted by ligand binding. Aberrant receptor proteins can be found in ovarian cancer. Whether aberrant receptor proteins are associated with transformation in general or with a variable clinical response to steroidal or anti-steroidal therapy is not known. Even after chemotherapy, steroid receptors are expressed in the metastases of ovarian cancers seen clinically, and they may have potential uses for localization and treatment of receptor-rich cancers. Radioligand pharmaceuticals appropriate for imaging or for site-directed radiocytotoxicity can be sequestered to the nuclei of receptor-rich cancers. Initial clinical imaging and therapy trials with such pharmaceuticals have been approved and begun. In the use of halogenated estrogen radiopharmaceuticals, liver metabolism and enterohepatic recirculation are important considerations. Ascites prolongs retention of a radiohalogenated estrogen in the abdominal cavity. Distant metastases have been localized with [123I]-estrogen in breast cancer patients in pre-operative procedures. Receptor-mediated cytotoxicity occurs when estrogen receptor radioligand pharmaceuticals that are Auger electron emitters are used in vitro.

Animals↗
PubMed1992

[Regulation of sterol carrier protein-2 in human luteal cells by LH and LH-RH].

Conversion of cholesterol to pregnenolone is the most important and, at the same time, the rate-limiting step of steroidogenesis. Sterol carrier protein-2 (SCP2) or nonspecific lipid transfer protein (nsL-TP) is an intracellular protein, which plays an important role in the pre- and transmitochondrial transport of cholesterol and for the mitochondrial synthesis of pregnenolone. Synthesis of pregnenolone in rat Leydig cells can be increased by LH and LH-RH; however, only LH leads to characteristic changes in intracellular concentrations of SCP2. This means that synthesis of pregnenolone is regulated in two different ways. In this study we aimed to find out whether such a 'second way' of steroidogenesis is also demonstrable for the human corpus luteum (i.e. human luteal cells). Human luteal cells were collected during follicle punctures and were cultured as described previously. We demonstrate that (human) LH/hCG are able to enhance pregnenolone synthesis; this process is accompagnied by typical changes of SCP2 and an increase in activity of 7-dehydrocholesterol reductase, which is a marker enzyme for SCP2. LH-RH was shown to exert no effect. Thus, we conclude that a second way of steroidogenesis (i.e. synthesis of pregnenolone) cannot be proved for the human corpus luteum.

Carrier Proteins↗
PubMed1991

Prolonged clearance of intraperitoneal 16 alpha-[125I]iodo-17 beta-estradiol in presence of ascites.

Radioestrogens have potential as adjunct therapeutic agents against ovarian carcinoma, because selected radionuclides can deposit lethal doses of radiation to tumor cells and many ovarian carcinomas and their metastases express estrogen receptors. Because intraperitoneal administration is a possible approach, we investigated absorption from the peritoneal cavity of a radioiodoestradiol after intraperitoneal application in rats with and without ovarian tumors and ascites and compared the distribution of the radioactivity with that obtained after intravenous injection. In the absence of ascites, 70% of the intraperitoneal dose was cleared into the intestine within 2 hours after injection, indicating fast absorption from the peritoneal cavity. In the presence of ascites, clearance of intraperitoneal radioiodoestradiol was considerably slower; at 2 hours after injection, 50% of the injected dose remained in the ascites, mostly as radioiodoestradiol. Uptake of radioactivity in estrogen receptor-rich tissues, e.g., uterus, after intraperitoneal injection was high (about 20:1 over blood), regardless of the presence of ascites, but moderately lower than that observed after intravenous injection of radioiodoestradiol.

Animals↗
PubMed1991

Biodistribution, with high uptake by the reproductive tract, of an intraperitoneally infused radiohalogenated steroidal estrogen-receptor ligand.

We infused [123I]16 alpha-(123I)-iodo-estradiol ([123I]E2) intraperitoneally (i.p.) into swine to study its biodistribution and to explore the i.p. use of radiohalogenated steroid estrogen-receptor (ER) ligands as a potential option for diagnosing and treating intra-abdominal, retroperitoneal, and distant sites of advanced ER-rich malignancies. Fifty to 80% of the radiolabel was absorbed from the peritoneal cavity within 30 minutes, and 30 to 50% of the infused radiolabel was excreted in the urine within 2 hr. The rate of biliary clearance was maximal within 25 minutes. At 3 hr, the ER-rich reproductive tract had greater than 63 times the concentration of radiolabel in blood; the former was blocked by non-labeled competitors for ER. Uptake by non-ER-rich tissues, compared to blood, ranged from 0.7:1 (heart and lungs) to 16:1 (spleen); the omentum, however, exhibited a concentration as high as 64:1, which was not blocked by non-labeled ER ligands. Uptake by ER-rich target tissue remained high when charcoal was used to prevent reabsorption of radiolabel from the digestive tract after its biliary excretion, and when the products of biliary excretion were removed by catheterization of the common bile duct. Neither charcoal nor exteriorization of bile appeared to affect urinary clearance of the radiolabel over the time course of the experiments. Taken together with the recent development of syntheses that yield radiohalogenated sex steroid receptor ligands of high specific activity, our findings are encouraging for the potential application of radiolabeled ligands as i.p. administered pharmaceuticals. The advantage of the i.p. route is that it provides direct uptake of the pharmaceutical by free-floating clusters and individual cancer cells in ascitic fluid, as well as delivery via the circulation to vascularized intra- and/or extraperitoneal metastases.

Abdomen↗
PubMed1991

Rapid liver metabolism, urinary and biliary excretion, and enterohepatic circulation of 16 alpha-radioiodo-17 beta-estradiol.

The radiohalogenated estrogen 16 alpha-[123I]iodo-17 beta-estradiol ([123I]E2) is emerging as a diagnostic tool for imaging of ER-rich malignant tumors, with potential application for site-directed radiotherapy. Clinical use requires an accurate accounting for the biodistribution of the radioactivity, including an assessment of its enterohepatic circulation. We investigated the metabolism and circulation of [125I]E2 in the enterohepatic system in swine, a pharmacokinetic model that resembles humans. With indicator dilution methods, we found that, after its injection into the portal vein, more than 99% of [125I]E2 was cleared from the blood by the liver during the first pass. Water-soluble metabolites were then partly released into the blood and partly excreted into bile. After injection of [125I]E2 into the external jugular vein, one-third of the radioactivity was excreted in bile and two-thirds in the urine. More than 90% of the radioactivity in urine and bile was that of [125I]E2-glucuronide or [125I]E2-sulfate; only a very small fraction of the excreted radioactivity was from free 125I. Radioactivity in bile collected from one swine after i.v. injection of [125I]E2, and then infused into the proximal duodenum of a second swine, was almost totally absorbed during passage through the intestine at 5-7 hr after infusion. The reabsorbed radioactivity was cleared in the urine.

Animals↗