A variant t(X;15)(p11;q22) translocation in acute promyelocytic leukemia

Nonrandom reciprocal translocations involving chromosomes #15 and #17 are characteristic anomalies in a great majority of cases of acute promyelocytic leukemia (APL). Other complex translocations in APL that invariably involve chromosome #17 also have been described. We describe a patient with clinical and morphologic characteristics of APL but with a previously undescribed acquired karyotype, t(X;15)(p11;q22). This is the first translocation in APL described in which chromosome #17 is not involved. Although a comparative structure/function analysis of potentially relevant genes to the translocation breakpoints in both t(X;15) and t(15;17) APL showed no major alterations, the enhanced expression of the c-Ki-ras oncogene observed in t(X;15) APL supports the concept of heterogeneity in APL at the cytogenetic and molecular levels.

Cellular control of in vitro progression of murine myeloid leukemia: progression accompanies acquisition of independence from growth factor and stromal cells

The ability of bone marrow stroma cells of normal WCB6F1 (+/+) mice versus their congenic Sl/Sld stromal-defective littermates to support sustained proliferation and leukemic transformation of the growth factor-dependent myeloid cell line FDC-P1 was studied. Extensive proliferation of factor-dependent cells occurred on (+/+) normal long-term marrow culture stroma without the addition of growth factor, whereas factor-dependent cells dissipated from Sl/Sld stromal cultures after addition. The sustained proliferation that occurred on +/+ stromal layers later resulted in the appearance of factor-independent cell lines that were no longer dependent upon stroma. Factor-independent cell lines were cloned by limiting dilution and analyzed for expression of cell surface antigens to prove their origin from FDC-P1. Factor-independent cells, but not factor-dependent cells, formed tumors in syngeneic mice. These studies demonstrate a critical role for marrow stroma in the stepwise development of murine leukemia and are concordant with the previous data obtained in in vivo studies by McCool et al. that the splenic stroma of irradiated Sl/Sld mice do not support growth of Friend virus-induced preleukemic cell colonies. The present data demonstrate in a preleukemia model not induced by Friend virus complex that normal (+/+) stromal cells promote the in vitro proliferation of factor-dependent preleukemic cells and their subsequent transition to factor-independent leukemia cells, but Sl/Sld defective stroma do not efficiently promote this transition.

Isolated nipple recurrence seventeen years after subcutaneous mastectomy for breast cancer--a case report

A case of nipple recurrence presenting 17 years after subcutaneous mastectomy for carcinoma is presented. The tumour had become less well differentiated but did not appear to have metastasized. This case highlights the problems of follow-up that will accompany the use of treatments that preserve part of the breast.

Evaluation of STS-557 as an oral contraceptive in male rat

To examine the nature and site of post-testicular antifertility action of STS-557 (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one), male rats were given the steroid orally daily for 60 days. In doses of 1 and 5 mg per animal per day it had no effect on fertility at the end of 3 weeks of treatment. When the treatment was extended for 60 days, spermatogenic arrest and loss of libido were evident in animals treated with 5 mg dose; animals receiving 1 mg dose of steroid showed no decrease of spermatogenesis or sexual activity and their fertility remained unaffected. In 35-day-old growing rats the steroid produced inconsistent effects on spermatogenesis after a 15-day treatment period at 1 and 5 mg doses. Both in adult and in growing rats the steroid caused a significant reduction in the weights and secretory function of the epididymis and other accessory sex organs; a dose-dependent response was seen in all the sex organs. Evaluation in castrated rat model revealed that STS-557 is a weak anti-androgen. Although this steroid is a potent inhibitor of spermatogenesis, its inhibitory effect on Leydig cell function is a contraindication for its use as a male oral contraceptive.

Hypoglycaemic and hypolipaemic effects of Cyamopsis tetragonoloba (guar) in normal and diabetic guinea pigs

Information available in literature is contradictory regarding the glycaemic and cholesterolaemic activities of various legume proteins. Present work deals with the study of the effect of 'Guar' feeding on serum total lipids, free and esterified cholesterol, triglycerides and phospholipids. Normal and alloxan induced diabetic guinea pigs were kept on the whole seed diet of 'Guar' for four weeks. Blood sugar and total lipid levels were found to be decreased significantly in normal and as well as diabetic animals; free and esterified cholesterol levels were also observed to be lowered significantly in normals, whereas esterified fraction alone was found to be lowered in diabetics. Significant fall in the levels of other lipids i.e., triglycerides, phospholipids and total lipids was also noticed.

Replication of the adeno-associated virus DNA termini in vitro

The validity of the model proposed by Cavalier-Smith for the replication of linear, single-stranded DNA molecules was tested by using subgenomic DNA termini isolated from adeno-associated virus (AAV), a defective parvovirus. In purified DNA replication systems, the terminal hairpin structure of AAV DNA with a 3'-OH end was shown to prime the synthesis of the daughter DNA strand, which was covalently linked to the parental strand. This resulted in the synthesis of a duplex DNA structure with a terminal hairpin. The availability of such a hairpin structure should facilitate the isolation and characterization of the pivotal enzyme, the putative nickase, for the replication of AAV DNA.

Testicular regulation and sub-cellular distribution of zinc in the epididymis and vas deferens of rhesus monkey (Macaca mulatta)

The zinc concentration in the epididymis (caput, corpus and cauda regions), vas deferens and caudal lobe of prostate of adult rhesus monkeys was determined by atomic absorption spectrophotometry. Zinc content (microgram/g wet weight) was found to be maximum in the prostate (709 micrograms) followed by epididymis and vas deferens. The three segments of the epididymis did not differ from one another in their zinc content (165-177 micrograms). On a protein basis maximum concentration of zinc was present in the nuclear fraction followed by microsomal, cytosolic and mitochondrial fractions in that order. Ligation of testicular efferent ducts or castration 90 days prior to autopsy caused a marked reduction in zinc concentration in different sub-cellular fractions of the organs examined; castration was relatively more effective in this regard. The importance of androgen and other testicular products in controlling zinc content and the possible physiological role of zinc in the male genital tract are discussed.

Neovascularization in human cutaneous melanoma: a quantitative morphological and Doppler ultrasound study

A study of tumour blood flow in 36 patients with 38 malignant melanomas using Doppler Ultrasound flowmetry has shown that tumour blood flow can be detected in most melanomas more than 0.9 mm thick, and is absent in most melanomas less than this thickness. Histological quantitation of blood vessels using lectin staining to delineate vascular endothelium and automated image analysis has shown a high degree of correlation between vascularity at the tumour base and tumour thickness. Since it is likely that the development of a vascular plexus at the tumour base is a prerequisite for dissemination, the development of these blood vessels may prove to be an independent prognostic factor for thin melanomas. This work also provides a new model for dynamic, in vivo investigation of the vascularity of human tumours.

Doppler ultrasound as an adjunct to the differential diagnosis of pigmented skin lesions

One hundred and forty-one pigmented skin tumours were examined with a 10 MHz ultrasound Doppler flowmeter to investigate the value of detecting blood flow in the diagnosis of raised pigmented skin lesions. Most of the benign lesions except for those with an angiomatous basis were devoid of blood flow signals while all basal cell carcinomas and 96 per cent of thick melanomas (greater than or equal to 0.9 mm) were associated with detectable Doppler frequency shift signals. While the characteristics of analysed Doppler waveforms are of research interest, the simple detection of blood flow by a hand held instrument gives sufficient information for clinical purposes. In practice this simple test has been sufficiently reliable to prove a useful adjunct in the diagnosis of raised pigmented skin lesions. It has been found particularly helpful in the common clinical problem of differentiation of nodular melanoma from basal cell papilloma and benign intradermal naevus. If such a lesion is thought to be benign, and has detectable flow signals, one should reconsider the diagnosis. Absence of flow signals is strong confirmation of a benign clinical diagnosis. The test should be regarded as an adjunct to clinical diagnosis since, in common with all noninvasive diagnostic techniques, false negative and false positive cases will be encountered. The technique is not appropriate to macular lesions since these are usually flow negative, irrespective of the pathology.

The significance of blood flow in cutaneous malignant melanoma demonstrated by Doppler flowmetry

The vascularity of malignant melanoma has been studied in 23 patients by Doppler ultrasonic frequency shift recordings. A 10 or 8 MHz directional Doppler probe was used and the signals were analysed on an Angioscan II spectrum analyser. No blood flow was detected in 7 primary melanomas each of thickness less than 0.75 mm and one recurrent subcutaneous nodule. Abnormal blood flow signals were detected in 8 primary melanomas--each of thickness greater than 1.2 mm--and in 7 skin nodules of secondary melanoma. Three tumours did not conform to the general pattern--one primary tumour 0.7 mm thick had abnormal blood flow signals whereas one primary lesion of 2 mm thickness and one secondary deposit were flow negative. Thus neovascularization corresponds in general to the cut-off point for good prognostic tumours, suggesting that it is a development of biological significance. This vascular pattern can be detected non-invasively by means of a Doppler probe and may have a prognostic importance, particularly with melanomas of the intermediate thickness range of 0.75-3.0 mm, where precise outcome cannot at present be predicted. The significance of an abnormal blood flow in one thin tumour remains to be determined from long-term follow-up.

Human alphoid family of tandemly repeated DNA. Sequence of cloned tetrameric fragments and analysis of familial divergence

Three tetramers of the 170 base-pair monomer repeat unit of human centromeric DNA (alphoid DNA) have been cloned and sequenced. Adjacent subunits differed in sequence by 30 to 45%, while dimers varied by 13 to 20% whether adjacent or not. Divergence was distributed unevenly across the monomeric sequence, such that two highly conserved segments adjoined clusters of insertions/deletions. Divergence, calculated from the cloned sequences or measured in uncloned DNA by thermal destabilization of mismatched reassociated duplexes, was far greater than previously estimated for the total human alphoid family. The population of these repeats within the human genome was not uniformly diverged, however, since restriction subsets of alphoid DNA contained as little as one-tenth the overall level of divergence. This indicates a hierarchical or familial structure of the genomic repeat population. Using cloned probes, human alphoid DNA was shown to be highly methylated and transcriptionally inactive. These data, along with evidence of conserved segments and periodicities (dimeric and higher-order) overlying considerable sequence diversity, support a structural role for this DNA family.

Zinc in the seminal vesicle and cranial and caudal prostate of rhesus monkey (Macaca mulatta): testicular regulation and subcellular distribution

Zinc concentration and its subcellular distribution in the seminal vesicle and cranial and caudal prostate of adult rhesus monkey was determined by atomic absorption spectroscopy. Its concentration (microgram/mg protein) was maximum in the caudal lobe of prostate (5.7 micrograms) followed by cranial prostate (2.8 micrograms) and seminal vesicle (1.26 microgram). Analysis of subcellular fractions revealed that zinc concentration was highest in the microsomal fraction constituting about 50% of total zinc in the two lobes of prostate (cranial: 5 micrograms; caudal: 17 micrograms/mg protein). A significant reduction occurred in their zinc content following castration. The possible role of zinc in the accessory sex glands is discussed.

c-Ha-ras-1 proto-oncogene amplification and overexpression during the limited replicative life span of normal human fibroblasts

The cellular proto-oncogene c-Ha-ras-1 undergoes up to 4-fold amplification during the limited replicative life span of normal human diploid fibroblasts in vitro. Levels of c-Ha-ras-1 messenger RNA and its p21 protein product are correspondingly elevated. Cellular proto-oncogene amplification and overexpression, although frequently associated with tumorigenesis, may thus occur during normal cellular growth.

Isolation of Acanthamoeba culbertsoni from a patient with meningitis

A case of amoebic meningitis, presumably primary, was encountered in the Christian Medical College Hospital, Vellore, South India, in November 1983. The patient, a 40-year-old man, had cerebrospinal fluid rhinorrhea before the meningitis developed. Acanthamoeba culbertsoni was repeatedly demonstrated in and cultured from the cerebrospinal fluid. The patient responded dramatically to a combination therapy of penicillin and chloramphenicol.

The distribution of zinc in the subcellular fractions of the rhesus monkey testis

The zinc content in the testis of sexually immature, adult, and efferent duct-ligated adult rhesus monkeys was determined by atomic absorption spectrophotometry. Zinc content (μg/g wet wt) was found to be high in adult testis (165.9) when compared to immature (68.9) or efferent duct-ligated (104.2) animals. Analysis of subcellular fractions revealed that the concentration of zinc (expressed in relation to protein) was maximum in the microsomal fraction. The possible significance of this trace metal as a constituent of membrane proteins and enzymes, and as an activator of mitochondrial function in testis, is discussed.

Autocrine regulation of growth: II. Glucocorticoids inhibit transcription of c-sis oncogene-specific RNA transcripts

The ductus deferens smooth muscle tumor cell line (DDT1MF-2) expresses c-sis proto-oncogene poly A+ RNA transcripts which are thought to encode at least one subunit of the potent mitogen platelet derived growth factor (PDGF). We have previously demonstrated that glucocorticoids block DDT1MF-2 cells in G0/G1 stage of the cell cycle, and that exogenously applied PDGF reinitiates cell cycle progression. In this paper we document that glucocorticoids act to inhibit cell cycle progression by inhibiting the expression of c-sis poly A+ transcripts, which we suggest are encoding a PDGF-like molecule for DDT1MF-2 cells.

Biochemical analysis of human seminal plasma. II. Protein, non-protein nitrogen, urea, uric acid and creatine

Seminal levels of protein, non-protein nitrogen (NPN), urea, uric acid and creatine were determined in human males divided as normal (Group I), azoospermia (Group II), infertile (Groups III, IV and V) with different sperm numbers and vasectomized (Group VI) cases. The geometrical mean level of seminal protein of Gr. I and Gr. V were significantly greater than that of Gr. IV. No significant difference in the levels of NPN and urea between any of the groups revealed. The seminal creatine level of Gr. I was significantly higher than that of Gr. III which in its turn was greater than that of Gr. VI, which recorded a value lowest of all the groups. Mean levels of uric acid of Gr. I was significantly greater than those of other five groups, taken individually. A direct correlation between uric acid level and sperm counts is an important observation that has emerged from this study.

Evidence for the involvement of coupling factor B in the H+ channel of the mitochondrial H+-ATPase

Membrane energization by ATP has been measured in vesicles containing purified bovine heart mitochondrial H+-ATPase (ATP synthase) with the voltage-sensitive dye oxonol VI. The dithiol chelator, Cd2+, and the thiol oxidant, copper o-phenanthroline, produced discharge of the membrane potential when added at the steady state and inhibited its establishment when added prior to energization by ATP. These effects, which were reversed by dithiothreitol, were not accompanied by an increase in the nonspecific H+ permeability of the membrane. Passive H+ conduction in proteoliposomes containing F0 (hydrophobic segment of ATP synthase) was assayed by the quenching of 9-aminoacridine fluorescence after establishing a K+ diffusion potential. This conductance was blocked by Cd2+, an inhibitor of coupling factor B (FB). Labeling of F0 with 115Cd2+ at the concentrations that inhibited the F0 conductance followed by gel electrophoresis yielded a single radioactive band with a molecular weight corresponding to FB, the presence of which in the F0 preparation was confirmed by immunoblot staining. The data offer strong evidence that FB is an essential component of the H+ channel of F0, because H+ conduction through the channel is inhibited by chemical modification of FB.

Zinc content in the epididymis, vas deferens, prostate, and seminal vesicles of juvenile rhesus monkey (Macaca mulatta): effect of androgen and estrogen

The zinc content in the three segments of the epididymis (caput, corpus, and cauda), vas deferens, seminal vesicles, and prostate of juvenile monkeys was determined by atomic absorption spectrophotometry. Zinc content (micrograms/gm wet weight) was found to be maximum (328) in the vas deferens; in the other organs it measured in the following order: caput 191, corpus 238, cauda 193, prostate 133 and seminal vesicles 85. In order to investigate the endocrine control of the zinc in these organs, two groups of animals were treated with testosterone propionate (2 mg) or estradiol dipropionate (10 micrograms) once daily for 30 days. In response to androgen, a rise in both concentration and content of zinc was evident only in the prostate. The results further suggested that the prostatic zinc may be under dual hormonal control, but in the epididymis and vas deferens it may be under the influence of estrogen. It is concluded that the hormonal effects on zinc content and growth stimulation in accessory sex organs are quite separate and may be under different hormonal control.

Biochemical analysis of human seminal plasma. I. Fructose, ascorbate, cholesterol, adenosine triphosphatase and lactic dehydrogenase

Seminal levels of fructose, ascorbate, cholesterol, adenosine triphosphatase (ATPase) and lactate dehydrogenase (LDH) were estimated in human males divided into normal (Group I), azoospermic (Group II), infertile (Groups III, IV and V with different sperm numbers) and vasectomized (Group VI) cases. The fructose level of the normal subjects (Gr. I) recorded the lowest geometric mean value and that of the azoospermic patients being the highest; other groups registered intermediate values. A significant difference was evident in the level of ascorbate between normal (Gr. I) and azoospermic (Gr. II) conditions, the level being higher in the normal group. The seminal ATPase activity of different groups varied inversely with the number of sperms, the mean value of the normal (Gr.I) being the lowest. The results suggest that determination of seminal ATPase and ascorbate levels is likely to yield some useful information about the semen quality.

Effect of irradiated dib-cAMP on the tonic and phasic activity of human myometrium

Cyclic AMP, used as dibutyryl derivative for better permeability, has a relaxing effect on smooth muscle preparations from human uterine tissue (surgical material). The observed decrease of tonus and frequency depends on the concentration applied, shown in the range between 50 and 300 microM. cAMP looses its physiological activity by irradiation in vitro; in addition an inhibitory action of the irradiation products on uterine tissue could be proved. From the data of the Lineweaver-Burk plots, showing the competition between non-irradiated and irradiated cAMP, a ten-to twentyfold higher affinity of the irradiation products to the receptor compared to that of this transmitter could be calculated. The results show that preparations of human origin with beta-receptors behave similarly to animal tissues with beta-receptors. They are further discussed with respect to a better understanding of dose-response curves for chemical and physiological inactivation.

Rescue of adeno-associated virus from recombinant plasmids: gene correction within the terminal repeats of AAV

We have isolated three types of pBR322-AAV recombinant plasmids that contain deletions within the 145 bp AAV terminal repeats. When the plasmids were transfected into human cells, mutants that contained deletions within the left (type I) or right (type II) terminal repeat were viable. Of four mutants examined that contained deletions in both termini (type III), only one was viable. All of the viable mutants produced AAV virions that contained wild-type AAV DNA. Furthermore, the viable type III deletion could be converted to a nonviable mutant by deleting all copies of an 11 bp sequence from its termini. We conclude that there is an efficient mechanism for correcting deletions within the AAV termini. A model that could account for these observations is also discussed.

Urethral myiasis

A case of urethral myiasis is reported. The authors are not aware of any such reference in the literature.

Nucleotide sequence and organization of the adeno-associated virus 2 genome

The complete nucleotide sequence of the adeno-associated virus 2 genome was determined. The single-stranded genome is 4,675 nucleotides in length and contains inverted terminal repeats of 145 nucleotides, the first 125 nucleotides of which form a palindromic sequence. Within the inverted terminal repetitions, there are two distinct sequences representing an inversion of 43 nucleotides that can exist on either terminus. The 5' and 3' termini of three major mRNA transcripts, which are present in both spliced and unspliced forms, were also mapped on the viral genome. Potential initiation and termination codons for efficient protein synthesis were identified, and genome segments were assigned that code for three major viral capsid proteins and, possibly, some as-yet-unidentified, nonstructural viral proteins.

Zinc content of maturing spermatozoa in oestrogen treated rats

Zinc content of spermatozoa collected from the caput and cauda portions of the rat epididymis was determined by atomic absorption spectroscopy. The results showed about 60% reduction in the spermatozoal zinc content by the time they reach the cauda epididymis. This reduction was inhibited in rats receiving micro dose oestrogen which induced 'functional' sterility. It appears that the fall in zinc content of spermatozoa during their transport in the epididymis is related to sperm maturation and that oestrogen treatment interferes with this reduction in sperm zinc content.

Sagittal diameter of the cervical canal in normal Indian adults

This paper is based on a radiographic study of 300 normal individuals from 18 to 34 years of age comprising 207 males and 93 females. A lateral radiograph of the cervical spine with a focal-film distance of 6 ft was obtained of each subject to measure the sagittal diameter of the cervical spinal canal. The mean sagittal diamter ranged from 21.43 mm at C1 to 16.42 mm at C7 in males and from 20.13 mm at C1 to 15.54 mm C7 in females. This diameter decreased from C1 down to C4 or C5 where there was a gradual but marginal increase to C6. This diameter was smallest at C7. In general the sagittal diameters In females were about 1 mm less than in males at all vertebral levels. The smallest sagittal diamter from C3 to C7 in both sexes was 13 mm. The largest sagittal diameter varied from 20.5 to 28 mm in males and 18.5 to 26 mm in females. The mean sagittal diameter showed some relationship to height in males. No significant difference was observed in relation to weight. The posterior component of the sagittal diameter was smaller in females than in males due to a difference in development of the laminae.

Zinc in the epididymal and vasal spermatozoa of rhesus monkey (Macaca mulatta)

Zinc level in maturing spermatozoa collected from caput, corpus, and cauda regions of the epididymis and vas deferens of rhesus monkey was measured. Spermatozoa collected from the caput epididymis have the highest concentration of zinc (36 micrograms/10(8) spermatozoa). There was a marked reduction in the zinc content of corpus spermatozoa and a further decrease in the spermatozoa of cauda epididymis. Thus the zinc content of spermatozoa gradually decreases as they migrate from the caput to cauda epididymis. There was a significant increase in the zinc content of vasal spermatozoa as compared to those collected from the cauda region of epididymis.

Determination of sulphur functions with iodoso-compounds

Iodoso derivatives, e.g., m- and p-chlorophenyl, m- and p-methylphenyl and p-nitrophenyl-iodosoacetates and o-diacetoxyiodobenzoate, have been thoroughly investigated as oxidants and are proposed as analytical reagents for the determination of thiols, thioureas, isothiocyanates, organic sulphides, disulphides, xanthates, dithiocarbamates, amines and alcohols in aqueous and non-aqueous (acetic acid, acetonitrile, dimethylformamide) media. The error of the determination of thiols is 0.2% thioureas 0.5%, organic sulphides and disulphides 0.4%, isothiocyanates 0.4%, dithiocarbamates 0.4%, and xanthates 0.5%. All the methods are precise to 0.2-0.5%. It is also shown that the properties of the o-derivatives differ markedly from those of the m- and p-derivatives. The o-derivatives contain a 1-substituted 1,2-benzoiodoxilin-3-one ring system. The stability of this system is apparently associated with the size of the five-membered ring; other compounds in which iodine is apparently part of larger rings are less stable. o-Diacetoxyiodobenzoate appears to be the best analytical reagent of the iodoso series. The m- and p-iodosobenzoates are found unsuitable for quantitative oxidation of cysteine.

Social interaction and neuroses (the family and the primary group): a pilot study

The present work examines the social interaction with the primary group of 30 neurotic patients and 30 matched controls. A comparison of the degree of family jointness in the two groups was also done keeping in view the nature of Indian family system and to find out the association, if any, it bears to social interaction. Evaluation instruments were Social Interaction Schedule (Henderson et al., 1978) and Khatri's Scale to Measure Jointness of Families in India (1970). The findings indicate that neurotic patients do not have a deficient primary group, as far as the numerical size and the duration and type of interaction is concerned. However, the patients appear to be less active than controls in making contacts with members of their primary group outside their household. Further, our group of patients perceived their personal lives to be deficient in some respects. Patients and controls did not differ with regard to the degree of family jointness as measured on Khatri's Scale.

Biochemistry of terminal deoxynucleotidyltransferase: identification, characterization, requirements, and active-site involvement in the catalysis of associated pyrophosphate exchange and pyrophosphorolytic activity

Terminal deoxynucleotidyltransferase (TdT) has been found to catalyze both pyrophosphate exchange and pyrophosphorolysis reactions. Both reactions are strongly inhibited by antiserum to TdT. The reactions require the presence of a divalent cation, a single- or double-stranded oligomeric or polymeric DNA or RNA, and deoxyribonucleoside triphosphates (for PPi exchange only). Of the three divalent cations tested, Mg2+ and Co2+ are equally effective, while Mn2+ neither is used for catalysis nor inhibits the Mg2+-catalyzed reactions. Ribonucleoside triphosphates have been found to support the PPi exchange reaction to a minor extent and have no inhibitory effect on the catalysis mediated by dNTPs. Inhibition studies, using SH group inhibitors, Zn chelator, and a substrate binding site specific reagent, revealed that PPi exchange and pyrophosphorolysis reactions may be distinguished by differences in their sensitivity to inhibition by various reagents. While the PPi exchange reaction is strongly inhibited by sulfhydryl reagents, o-phenanthroline, and pyridoxal phosphate, the pyrophosphorolysis reaction is insensitive to these reagents. In addition, the pyrophosphorolysis reaction is also found not to require a free 3'-OH terminus of a primer. This difference in the susceptibility of the two reactions indicates that discrete active-site structures exist in TdT which catalyze PPi exchange and pyrophosphorolysis reactions.

Increased susceptibility of rabbits to intravenous challenge with Mycobacterium avium after mild hepatitis produced by carbon tetrachloride

A mild grade of liver damage in rabbits was produced by giving 23 subcutaneous injections of carbon tetrachloride (CCl4). The CCl4-treated rabbits and untreated controls were subsequently challenged with the mildly virulent strain of Mycobacterium avium Kirschberg (TMC 801). In two successive experiments it has been found that liver damage increased the susceptibility of rabbits to infection with this organism.

Enzymatic activities associated with avian and murine retroviral DNA polymerases. Catalysis of and active site involvement in pyrophosphate exchange and pyrophosphorolysis reactions

Reverse transcriptase isolated from avian myeloblastosis virus (AMV) and Rauscher murine leukemia virus (RLV) were examined for their ability to catalyze polymerization, ribonuclease H, pyrophosphate exchange, and pyrophosphorolysis reactions. A detailed characterization and a study of requirements for the expression of pyrophosphate exchange and pyrophosphorolysis reactions indicated that a variety of RNA and DNA template-primers supported these catalytic reactions. Furthermore, hydrogen bonding of template to primer was essential, although RNA:RNA template-primers, e.g. poly(rA) . (rU)9 or 70 S RNA . tRNA complex, were not utilized for these reactions. AMV enzyme required Mg2+, and RLV enzyme Mn2+, as the preferred divalent metal ion for the expression of these activities. Response of various catalytic reactions to site-specific inhibitors revealed that polymerization and pyrophosphate exchange reactions were susceptible to reagents that affected either the substrate or the template binding site, intrinsic zinc, or sulfhydryl groups. RNase H and pyrophosphorolysis activities, on the other hand, exhibited susceptibility only to the template site-specific reagent. We, therefore, conclude that RNase H and pyrophosphorolysis reactions are catalyzed through the template binding site while polymerization and pyrophosphate exchange reactions require additional participation of the substrate binding site, as well as that of intrinsic zinc and the presence of reactive sulfhydryl groups.