Ultrasound studies in varicocele

Renal function, the anatomic and functional status of the vena cava inferior, renal arteries and veins, and spermatic veins were evaluated in healthy individuals and patients with varicocele before and 12 months after laparoscopic ligation of the left spermatic vein. The renal vessels were assessed by color Doppler ultrasonography and renal function was examined by complex radionuclide study with 99mTc-pentatech. There were no significant changes in the diameter of renal arteries and vena cava inferior and the right arterial blood flow velocities in healthy individuals and patients. No difference were found in the diameter of renal veins and in the blood flow velocity in renal arteries and veins. The enlarged renal veins and decreased mean blood flow velocity in the left renal vein in healthy persons and patients with varicocele and lower blood flow in the left renal artery than in the right one indicate left-sided renal hypertension that is attributable to left renal vein overload due to a great variety of collaterals and to compression at the site of "a forcepts". At the same time 12-month postoperative ultrasonic, Doppler and complex radionuclide studies revealed no significant changes in the diameter and blood flow velocity in the left renal vein.     

Saccharomyces cerevisiae MutLalpha is a mismatch repair endonuclease

MutL homologs are crucial for mismatch repair and genetic stability, but their function is not well understood. Human MutLalpha (MLH1-PMS2 heterodimer) harbors a latent endonuclease that is dependent on the integrity of a PMS2 DQHA(X)2E(X)4E motif (Kadyrov, F. A., Dzantiev, L., Constantin, N., and Modrich, P. (2006) Cell 126, 297-308). This sequence element is conserved in many MutL homologs, including the PMS1 subunit of Saccharomyces cerevisiae MutLalpha, but is absent in MutL proteins from bacteria like Escherichia coli that rely on d(GATC) methylation for strand directionality. We show that yeast MutLalpha is a strand-directed endonuclease that incises DNA in a reaction that depends on a mismatch, yMutSalpha, yRFC, yPCNA, ATP, and a pre-existing strand break, whereas E. coli MutL is not. Amino acid substitution within the PMS1 DQHA(X)2E(X)4E motif abolishes yMutLalpha endonuclease activity in vitro and confers strong genetic instability in vivo, but does not affect yMutLalpha ATPase activity or the ability of the protein to support assembly of the yMutLalpha.yMutSalpha.heteroduplex ternary complex. The loaded form of yPCNA may play an important effector role in directing yMutLalpha incision to the discontinuous strand of a nicked heteroduplex.     

PARP-1 enhances the mismatch-dependence of 5'-directed excision in human mismatch repair in vitro

End-directed mismatch-provoked excision has been reconstituted in several purified systems. While 3'-directed excision displays a mismatch dependence similar to that observed in nuclear extracts (≈20-fold), the mismatch dependence of 5'-directed excision is only 3-4-fold, significantly less than that in extracts (8-10-fold). Utilizing a fractionation-based approach, we have isolated a single polypeptide that enhances mismatch dependence of reconstituted 5'-directed excision and have shown it to be identical to poly[ADP-ribose] polymerase 1 (PARP-1). Titration of reconstituted excision reactions or PARP-1-depleted HeLa nuclear extract with purified PARP-1 showed that the protein specifically enhances mismatch dependence of 5'-directed excision. Analysis of a set of PARP-1 mutants revealed that the DNA binding domain and BRCT fold contribute to the regulation of excision specificity. Involvement of the catalytic domain is restricted to its ability to poly(ADP-ribosyl)ate PARP-1 in the presence of NAD(+), likely through interference with DNA binding. Analysis of protein-protein interactions demonstrated that PARP-1 interacts with mismatch repair proteins MutSα, exonuclease 1, replication protein A (RPA), and as previously shown by others, replication factor C (RFC) and proliferating cell nuclear antigen (PCNA) as well. The BRCT fold plays an important role in the interaction of PARP-1 with the former three proteins.     

Endonucleolytic function of MutLalpha in human mismatch repair

Half of hereditary nonpolyposis colon cancer kindreds harbor mutations that inactivate MutLalpha (MLH1*PMS2 heterodimer). MutLalpha is required for mismatch repair, but its function in this process is unclear. We show that human MutLalpha is a latent endonuclease that is activated in a mismatch-, MutSalpha-, RFC-, PCNA-, and ATP-dependent manner. Incision of a nicked mismatch-containing DNA heteroduplex by this four-protein system is strongly biased to the nicked strand. A mismatch-containing DNA segment spanned by two strand breaks is removed by the 5'-to-3' activity of MutSalpha-activated exonuclease I. The probable endonuclease active site has been localized to a PMS2 DQHA(X)(2)E(X)(4)E motif. This motif is conserved in eukaryotic PMS2 homologs and in MutL proteins from a number of bacterial species but is lacking in MutL proteins from bacteria that rely on d(GATC) methylation for strand discrimination in mismatch repair. Therefore, the mode of excision initiation may differ in these organisms.     

GABA metabolism and the formation of a sensorimotor cortex evoked potential in the presence of excess zinc ions

Changes in GABA content, the enzymatic activity of its metabolism and the formation of sensorimotor cortical evoked potential (EP) were studied following long-term ZnCl2 administration. It has been established that a single ZnCl2 injection at a dose of 0.1 and 1 mg/kg was accompanied by an increase in the amplitude of sensorimotor cortical EP, though GABA accumulation in this brain structure was observed. This might account for the prolongation of the period of the potential appearance. Long-term (for 7, 14, 21 days) ZnCl2 administration at a dose of 0.1 mg/kg produced a sharp depression in the potential appearance and an increase in GABA content by 50% with the enhancement of glutamate decarboxylase activity and the attenuation of GABA-transaminase activity.     

Aflatoxicosis in rabbits: Effectiveness of Egyptian raw bentonite in prevention or diminution the detrimental effects of naturally aflatoxin contaminated diets

Thirty five females and 15 males of New Zealand White mature rabbits about 6 months of age, were assigned to 1–5 dietary treatments (7 does+3 bucks for each): uncontaminated control diet, naturally aflatoxin contaminated diet without or with 1,2 and 3% bentonite. Rabbit fed with the aflatoxin-diet had a decreased (P<0.01 or 0.05) physical semen characteristics of bucks and a reproductive performance traits of does. The values of conception rate (%), gestation length (days), litter size (n) and litter weights (g) at birth and viability (%) of litters of doe rabbits, fed with the aflatoxin-diet, recorded, respectively: 64.5; 31.0; 4.4; 275.0 and 57.1 versus 85.6; 30.3; 7.9; 508.0; and 100 for those fed with the uncontaminated diet. Addition of bentonite to the aflatoxin contaminated diet improved in general the physical semen characteristics of buck and reproductive performance traits of doe rabbits. The results of the study demonstrate that adding 1% of Egyptian raw bentonite to the naturally aflatoxin contaminated rabbit diets can provide an effective, cheap and safe practical technique for preventing the aflatoxicosis in mature rabbits.