Applications of mannose-binding lectins and mannan glycoconjugates in nanomedicine.

Glycosylated nanoparticles (NPs) have drawn a lot of attention in the biomedical field over the past few decades, particularly in applications like targeted drug delivery. Mannosylated NPs and mannan-binding lectins/proteins (MBL/MBP) are emerging as promising tools for delivery of drugs, medicines, and enzymes to targeted tissues and cells as nanocarriers, enhancing their therapeutic benefits while avoiding the adverse effects of the drug. The occurrence of plenty of lectin receptors and their mannan ligands on cell surfaces makes them multifaceted carriers appropriate for specific delivery of bioactive drug materials to their targeted sites. Thus, the present review describes the tethering of mannose (Man) to several nanostructures, like micelles, liposomes, and other NPs, applicable for drug delivery systems. Bioadhesion through MBL-like receptors on cells has involvements applicable to additional arenas of science, for example gene delivery, tissue engineering, biomaterials, and nanotechnology. This review also focuses on the role of various aspects of drug/antigen delivery using (i) mannosylated NPs, (ii) mannosylated lectins, (iii) amphiphilic glycopolymer NPs, and (iv) natural mannan-containing polysaccharides, with most significant applications of MBL-based NPs as multivalent scaffolds, using different strategies. Graphical abstract: Mannosylated NPs and/or MBL/MBP are coming up as viable and versatile tools as nanocarriers to deliver drugs and enzymes precisely to their target tissues or cells. The presence of abundant number of lectin receptors and their mannan ligands on cell surfaces makes them versatile carriers suitable for the targeted delivery of bioactive drugs.

The Lactate and the Lactate Dehydrogenase in Inflammatory Diseases and Major Risk Factors in COVID-19 Patients.

Lactate dehydrogenase (LDH) is a terminating enzyme in the metabolic pathway of anaerobic glycolysis with end product of lactate from glucose. The lactate formation is crucial in the metabolism of glucose when oxygen is in inadequate supply. Lactate can also be formed and utilised by different cell types under fully aerobic conditions. Blood LDH is the marker enzyme, which predicts mortality in many conditions such as ARDS, serious COVID-19 and cancer patients. Lactate plays a critical role in normal physiology of humans including an energy source, a signaling molecule and a pH regulator. Depending on the pH, lactate exists as the protonated acidic form (lactic acid) at low pH or as sodium salt (sodium lactate) at basic pH. Lactate can affect the immune system and act as a signaling molecule, which can provide a "danger" signal for life. Several reports provide evidence that the serum lactate represents a chemical marker of severity of disease similar to LDH under inflammatory conditions. Since the mortality rate is much higher among COVID-19 patients, associated with high serum LDH, this article is aimed to review the LDH as a therapeutic target and lactate as potential marker for monitoring treatment response of inflammatory diseases. Finally, the review summarises various LDH inhibitors, which offer potential applications as therapeutic agents for inflammatory diseases, associated with high blood LDH. Both blood LDH and blood lactate are suggested as risk factors for the mortality of patients in serious inflammatory diseases.

Status of mannose-binding lectin (MBL) and complement system in COVID-19 patients and therapeutic applications of antiviral plant MBLs.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a virus called "Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)." In the majority of patients, infection with COVID-19 may be asymptomatic or may cause only mild symptoms. However, in some patients, there can also be immunological problems, such as macrophage activation syndrome (CSS) that results in cytokine storm syndrome (CSS) and acute respiratory distress syndrome (ARDS). Comprehension of host-microbe communications is the critical aspect in the advancement of new therapeutics against infectious illnesses. Endogenous animal lectins, a class of proteins, may perceive non-self glycans found on microorganisms. Serum mannose-binding lectin (sMBL), as a part of the innate immune framework, recognizes a wide range of microbial microorganisms and activates complement cascade via an antibody-independent pathway. Although the molecular basis for the intensity of SARS-CoV-2 infection is not generally understood, scientific literature indicates that COVID-19 is correlated with unregulated activation of the complement in terms of disease severity. Disseminated intravascular coagulation (DIC), inflammation, and immune paralysis contribute to unregulated complement activation. Pre-existing genetic defects in MBL and their association with complement play a major role in immune response dysregulation caused by SARS-CoV-2. In order to generate anti-complement-based therapies in Covid-19, an understanding of sMBL in immune response to SARS-CoV-2 and complement is therefore essential. This review highlights the role of endogenous sMBL and complement activation during SARS-CoV-2 infection and their therapeutic management by various agents, mainly plant lectins, since antiviral mannose-binding plant lectins (pMBLs) offer potential applications in the prevention and control of viral infections.

LDH-C4: a target with therapeutic potential for cancer and contraception.

The lactate dehydrogenase (LDH) has been studied widely because it exists in various isozymic forms. The association of A and B subunits of LDH can generate five tetrameric isozymes, but the finding of the sixth isozyme in mature human testis and sperm indicated the presence of an additional subunit of LDH, designated as LDH-X (also termed LDH-C4 due to tetrameric nature of C-subunit). LDH-C4 isozyme is an iso-, allo-, and auto-antigen present in mammalian sperm cells. The synthesis of LDH-C4 in the testis takes place during sexual maturation, and it is the predominant fraction in mature spermatozoa. Though, originally considered to be testis specific, LDH-C or Ldh3 in mice was later detected in the murine oocyte and early embryo. Ldh3 in mouse supports its role in energy production in spermatids that favor lactate as substrate and in spermatozoa with a characteristic aerobic glycolytic path to yield ATP. During last two decades, cancer/testis-associated genes (CTAs) which are expressed only in the germinal epithelium of the testis are also expressed in some cancer cells, but not in non-cancerous somatic tissues. The CTAs are considered promising candidates for diagnosis and immunotherapy of cancer. The sperm-specific Ldh-c gene has been shown to express in a broad spectrum of human tumors, with high frequency in lung cancer, melanoma, and breast cancer; the protein being expressed virtually in all tumor types tested. Accordingly, LDH-C4 is the unique target for contraception in both males and females and offers potential future for immunotherapy of different types of cancers. As LDH-C has a preference for lactate as a substrate, LDH-C activation in cancer may depend on lactate for ATP production. The major aim of this article is to review the salient features of LDH-C subunit and the immune responses of LDH-C4 in homologous and heterologous species in relation to its role in acceptance or rejection of the allograft and its application in contraception and immunotherapy of cancer, directly or indirectly through the regulation of its substrate, the lactate.

Newly exposed immunochemically cross-reactive epitopes in sperm-specific LDH after glucosylation and gossypol interaction.

PROBLEM: In a previous study, mouse lactate dehydrogenase-C4 (LDH-C4) after chemical modifications with gossypol (Gossy-LDH-C4) and glucosylation with lactose (Glu-LDH-C4) was found to induce high immunological infertility in allogenic mice. In the present study, the characterization of antibodies and cross reactivity of the antisera produced against Gossy- and Glu-LDH-C4 with purified somatic isozymes are being reported. METHODS: Allo-antisera generated in Balb/c mice (i.r. route) against one primary (50 microg) and two secondary doses (30 x 2 microg) in Al(OH)3 were tested for cross-reactivity by ELISA and antibody avidity using Scatchard plot and Sip's plot. RESULTS: Results suggested that IgG against native LDH-C4 failed to recognize somatic isozyme, while antisera against chemically modified LDH-C4 consistently reacted with purified LDH from kidney and placenta. Scatchard plots and antibody saturation curves of native and complexed LDH supported the presence of heterogenous antibodies with a mean association constant (Ka) of the order of 10(6)-10(7) M(-1), whereas diversity of heterogeneity, defined by diversity constant (a), ranged between 0.89 and 1.23. In general, anti-Glu-LDH-C4 antiserum and native LDH-C4. reacted with higher Ka (low affinity) with a diversity constant of 0.89 compared with interaction between native LDH-C4 and it's antibodies. CONCLUSIONS: It is concluded that LDH-C4 is not an immunochemically sperm-specific protein, in which crossreactive epitopes are hidden within its conformation. Due to the large intake of cotton seed (a source of gossypol) by cattle, its unrefined oil by humans in various parts of the world, and the prevelance of diabetic state all the world over, the present study warns of immunological consequences in situ following gossypol interaction and glucosylation of LDH and conformationally related proteins in circulation.

Regulation of immune functions by sperm-specific LDH and its differences with somatic isozyme in primary and secondary lymphocyte cultures.

PROBLEM: Sperm-specific lactate dehydrogenase-C4 (LDH-C4) is an autoantigen that produces experimentally induced autoimmune orchitis in testes. In the present study, immunological functions of B and T cells have been examined and compared after immunization with sperm-specific LDH and the LDH from somatic cells. METHODS: Three sets of experiments were performed. In the first set, effects of Balb/C LDH isozymes at 10(-3) - 1 L microg/well were investigated: (i) by mixed lymphocyte cultures (MLC) using C-57 B1/6 female cells as responders and AKR lymphocytes (irradiated) as stimulators, (ii) for regulatory T cell activity in MLC co-cultured along with Con-A-induced AKR lymphoblasts and (iii) for modulation of lymphocyte activation by PHA in vitro. In the second set of experiments, female mice (C-57 B1/6) were distributed in six groups for various treatments: i) saline (as vehicle), ii) adjuvant, iii) LDH-B4 (20 x 3 microg), iv) LDH-B4 (40 x 3 microg), v) LDH-C4 (20 x 3 microg), and v) LDH-C4 (40 x 3 microg). Mice were hyperimmunized with -B4 or -C4 (Balb/c) with a primary dose of 20 or 40 microg of protein per mouse, emulsified in Freund's complete adjuvant (FCA) and two identical doses in Freund's incomplete adjuvant (s.c.) within 22 days. Saline (group i) or adjuvant treated dams (group ii) served as controls. One week after the second booster, sera were tested for IgG response and lymphocytes harvested for polyclonal activation in vitro using LPS and Con-A as mitogens. In the third set of experiments, female Balb/c mice were divided into six groups as in the second experiment and immunized with a single primary dose of isogenic LDH-B4 or LDH-C4 at 20 or 40 microg of protein in FCA. On day 5, after sensitization with LDH, lymphocytes were evaluated for mitogenesis and for IgM production in vitro using LPS and Con-A as mitogens. RESULTS: i) Primary MLC(s) were non-specifically suppressed in the presence of 10(-3)- 1 L x microg allogenic LDH-C4 or -B4, although LDH-C4 tended to abolish MLC completely. But MLC co-cultured with blast cells was suppressed by LDH-C4 alone, indicating that sperm LDH suppresses induced formation of regulatory T cells. ii) FCA primed lymphocytes in situ were significantly inhibited for Con-A stimulation in vitro. Since LPS stimulation remained unaffected, it appeared that FCA is immunosuppressive for T cell proliferation alone. iii) Cells primed with LDH increased mitogenic activity of LPS several fold, although LDH-C4 was less effective than LDH-B4 in sensitization of B lymphocytes. iv) However, effect of Con-A in mitogenesis was dose-dependent, viz. cells primed at 20 x 3 microg of each isozyme overcame the immunosuppressive nature of FCA by bringing back the SI ( x 25) equivalent to saline primed cells, while pre-treatment of cells with 40 x 3 microg LDH-C4 abolished SI completely, indicating that -C4 primed cells were immunologically suppressed for Con-A stimulation. Such a response was markedly visible when allogenic LDH-C4 was used for hyperimmunization; lymphocytes challenged with somatic LDH under similar conditions did not react. Loss of T cell functions by LDH-C4 was confirmed in the presence of PHA in primary cultures. v) For antibody responses, although sperm LDH was highly reactive and dose-dependent, somatic LDH was also immunogenic for IgG production in serum to a lesser degree. Besides, IgM antibody was also discernible by two isozymes in LPS-induced cultures. Significantly, -C4 primed cells at the higher dose, in comparison with the lower dose, were less responsive for IgM production. CONCLUSIONS: It is concluded that LDH(s) from sperm and somatic cells share functionally related antigenic epitopes that can generate/modify immune responses in vivo and in vitro with qualitative differences. However, immunosuppressive determinant of LDH-C4 is cell specific and dose selective.

Molecular and kinetic properties of sperm specific LDH after radiation inactivation.

Radiation inactivation of sperm specific lactate dehydrogenase-C4 (LDH-C4) has been studied and compared with the somatic LDH in aqueous solution. D37 of C isozyme was 470 Gy and that of B isozyme was 520 Gy. Semi-log plots of log N/No versus dose suggested that the inactivation of two LDH isozymes in presence of normal saline follows a single hit kinetics. Target molecular weight calculated by radiation analysis was found as 1.52 x 10(5) gm/mole for LDH-C4 and 1.38 x 10(5) gm/mole for LDH-B4. SDS-PAGE of irradiated enzymes showed a band of 35 kDa but did not indicate the presence of any other extra band, when compared with sham-irradiated enzymes. Chemical kinetics of residual activity following irradiation at D37 showed decrease in Vmax with coenzymes and primary substrates. However, decrease in Km was seen with pyruvate as increasing substrate. Nevertheless, K did not change when NAD+ was the leading substrate for LDH-B4 or LDH-C4. A hyperchromicity in intrinsic fluorescence and a blue shift in lambdamax over sham-irradiated LDH-C4 revealed the exposure of buried tryptophan residues to the surface after radiation inactivation. Results suggest that inspite of presence of variant amino acids, the conformations of two isozymes are stabilized by similar forces which behave in a similar way for radiation inactivation in aqueous phase.

State of pregnancy modifies lead toxicity in mice.

Toxicity of lead acetate after administration through the oral route at 0-50 mg/kg body weight of animal has been assessed in the liver of pregnant mice and compared with the effect in the liver of nonpregnant dams. Analysis showed that the basal level of hepatic lead is considerably reduced during pregnancy as compared to that in nonpregnant state. After administration of Pb-acetate, deposited lead in liver of nonpregnant mice was 3- to 4-fold while in pregnant mice was, it was 1.8- to 3.0-fold over their respective control values. Although hepatic Fe, Cu, and Zn levels had a tendency to be lowered during pregnancy, it appeared that the added trace quantity of lead prior to and during pregnancy helped in the retention of these metals, which either remained unaffected (as Fe) or declined (Cu and Zn) after lead administration during the nonpregnant state. The effect of lead on Mn diminution, however, was visible at the dose of 50 mg/kg body wt of lead-acetate. Alkaline phosphatase, which increased during pregnancy along with Mn, was reversed between the pregnant and nonpregnant states after oral administration of lead. On the other hand, the level of delta-aminolevolunic acid dehydratase, which declined during normal pregnancy, continued to fall further after lead exposure. It is concluded that the distribution of basal or administered lead and its effect on enzyme activities and trace metal composition in liver depends on the pregnant and nonpregnant states of female hosts.

Role of GABA receptor complex in low dose lindane (HCH) induced neurotoxicity: neurobehavioural, neurochemical and electrophysiological studies.

Lindane is widely used as an insecticide and scabicide in mammals. High doses in chronic exposures caused hyperexcitability and convulsions and impaired motor activity involving GABA-ergic mechanism. To investigate the role of GABA/Benzodiazepine mechanism in the neurotoxicity of low doses of lindane, rats were administered 2, 3, or 5 mg/kg orally for 90 days and behavioural, electrophysiological, and neurochemical studies were conducted. The animals exposed to lindane exhibited increased geotaxis and decreased spontaneous drug-induced locomotor activity (which further potentiated by phenobarbitone and increased after leptazol). The EEG of the treated rats showed high voltage slow-wave activity (HVSA) patterns with occasional spindles (9-10 HZ-amplitude of 100 uv). A significant increase (p < 0.01) in GABA levels in cerebellum and significant increase in benzodiazepine receptors in cerebellar membrane measured by (3H)flunitrazepam binding were observed in the animals exposed to 3 and 5 mg lindane. The study suggests that low dose chronic exposure of lindane causes neurobehavioral, neurochemical, and electrophysiological effects involving GABA-ergic mechanism(s).

Trace metals and metalloenzymes in placenta after oral administration of lead acetate.

The present study was carried out to find the effects of Pb acetate (10-50 mg/kg body wt) after oral administration on: 1. The distribution of elements, such as Fe, Cu, Zn, and Mn; 2. The activity of 6-amino levulenic acid dehydratase (delta-ALAD) and alkaline phosphatase (PAP); and 3. On the level of reduced glutathione (GSH) in murine placenta. Pb toxicity expressed on a dry-wt basis was reflected in terms of deficiency of delta-ALAD and PAP and enhanced content of GSH. Analysis of trace elements following Pb exposure showed low levels of Mn and Cu. Although Fe composition of placenta remained within normal range with increasing load of endogeneous Pb, Zn decline was not consistent after oral feeding of Pb acetate. Deficiency of PAP after Pb exposure did not correlate with the endogeneous levels of Pb or Zn therein, but correlated with endogeneous levels of Mn. Placental deficiencies of Cu and Mn have been related to the disturbed placental functions by Pb accumulation.

LDH-C4-substrate binary complexes studied by intrinsic fluorescence method.

Lactate dehydrogenase-C4 (LDH-C4) has been studied in presence of substrates using intrinsic fluorescence measurements. Excitation maximum of LDH-C4 occurred at 282 nm whereas fluorescence emission maximum was obtained at 340 nm. Fluorescence intensities at 340 nm showed that ligands viz. NAD+, NADH, pyruvate and lactate quench the relative fluorescence intensities of LDH-C4 in a concentration dependent manner. NAD+ and NADH produced a maximum quenching between 92-93% while pyruvate and lactate quenched the fluorescence of LDH up to 29% and 21% respectively. Association constants (Ka) based on fluorescence measurements were 6.05 x 10(4)M-1, 20 x 10(4)M-1, 0.113 x 10(4)M-1 and 0.3 x 10(4)M-1, for NAD+, NADH, lactate and pyruvate respectively. Stern-Volmer constants (Ksv) show that NAD+ and NADH have single Ksv of 4.07 x 10(4)M-1 and 1.47 x 10(5)M-1, whereas lactate and pyruvate indicated quenching reaction to be made up of two components. Ksv at low and high concentration of lactate respectively were 0.645 x 10(2)M-1 and 0.05 x 10(2)M-1, whereas corresponding Ksv with pyruvate were 1.008 x 10(3)M-1 and 0.408 x 10(3)M-1. Low Ksv at higher concentrations suggested that the aromatic chromophores are located within a hydrophobic environment. Red shift in fluorescence maximum (lambda max) by 2nm with lactate and 6nm with pyruvate showed that interaction of these ligands with LDH-C4 exposes some buried chromophores of the enzyme to the surface.

Immune responses of chemically modified homologous LDH-C4 and their effect on fertility regulation in mice.

PROBLEM: Lactate dehydrogenase-C4 (LDH-C4) is an iso-, allo- and auto-antigen of mammalian sperm. In spite of being cell specific, LDH-C4 does not induce infertility in females of homologous species after immunization. The present study examines the application of homologous LDH-C4 after chemical modifications in the immunological infertility of female mice. METHODS: LDH-C4 from testes of LACA mice was chemically modified by interacting it with gossypol (gossy-LDH-C4) and glucosylation with lactose (Glu-LDH-C4) in vitro and evaluated for immune responses and induced immunological infertility in allogeneic Balb/c mice after inoculation through intrarectal route using A1(OH)3 as adjuvant. RESULTS: Native LDH-C4, which elicited high antibody response after immunization with a primary (50 microgram) and three secondary doses (30 micrograms each) at an interval of 15 days each, did not reduce fertility significantly in mice. In contrast, study provides evidence that chemically modified LDH-C4 induces high infertility, since 85-100% of mice failed to conceive in two independent sets of experiments. Mice inoculated with modified LDH-C4 were associated with 2-3 fold anti-LDH-C4 antibody titre compared to antibody response elicited by native LDH-C4. Splenocytes from immunized non-pregnant mice were evaluated for polyclonal activation using Con A as mitogen. It was found that splenocytes primed with native LDH-C4 were significantly more stimulated than the non-immune control cultures. However cells primed with gossy-LDH-C4 were non-reactive to Con A and cells primed with glu-LDH-C4 were suppressed for ConA proliferation. CONCLUSIONS: It is concluded that LDH-C4-gossypol adduct offers a potential application in the induction of infertility of homologous species in marked contrast to native LDH-C4. Application of A1(OH)3 as adjuvant in the induction of immune response through intra-rectal route has been suggested.

Quenching of intrinsic fluorescence of sperm specific LDH by optical isomers of gossypol.

Intrinsic fluorescence of LDH-C4 has been studied in the presence of optical isomers of gossypol. The study showed that fluorescence due to tryptophan residues after excitation of LDH at 282 nm is quenched by each gossypol enantiomere in a concentration dependent manner. Half of the maximum quench (Q50%) of enzyme occurred with gossypol (-) at 0.9 x 10(-4) mol/l and with gossypol (+) at 1.4 x 10(-4) mol/l showing a maximum quench (Qmax) of 45% and 65% respectively, with a corresponding association constant (Ka) of 1.0 x 10(4) l/mol and 0.4 x 10(4) l/mol. Stern-Volmer constant (Ksv) inferred that quenching of LDH comprises at least two components with two different Ksv values. Ksv(I) and Ksv(II) between LDH-C4 and gossypol (-) were 1.97 x 10(3) l/mol and 1.22 x 10(3) l/mol, and those between LDH-C4 and gossypol(+) were 2.3 x 10(3) l/mol and 1.56 x 10(3) l/mol. Smaller Ksv at higher concentrations of gossypol indicated that some of the tryptophan residues in LDH-C4 are deeply buried within a hydrophobic environment. There was no blue or red shift of LDH-C4 when interacting with either of the gossypol enantiomeres.

Sex dependent immune responses by allogenic LDH isozymes.

Regulatory effects on polyclonal activation of primed splenocytes have been studied following immunization through the intrarectal route with allogenic sperm specific lactate dehydrogenase (LDH-C4) and somatic LDH from kidney. Results indicate that LDH primed cell proliferation by mitogens is dependent on the nature of the isozyme and sex of donor cells. Compared to somatic LDH, LDH-C4 was immunosuppressive for T cell proliferation in vitro and the effect was more significant with female splenocytes as compared to male spleen cells. However, the suppressive effect of LDH-C4, on B cell function was identical in both males and females. In contrast to the somatic LDH which did not produce alloantibody in significant amount, LDH-C4 was highly immunogenic in production of humoral antibody in female mice. Alloantibody formation in dams was substantiated with a similar degree of immune regulation of B cell functions as shown by lipopolysaccharide stimulation. The role of LDH-C4 in protection of allogenic sperm in the female genital tract has been suggested. However, it is concluded that recipients of sperm constituents through the intrarectal route are at greater risk for immune suppression and bacterial/viral infection.

Molecular inactivation of testicular hyaluronidase in solid state after proton irradiation: a study based on target size, substrate binding and thermodynamic analysis of heat denaturation.

Dose response activity curve of testicular hyaluronidase (HDase) following proton irradiation in dry state follows complicated mechanisms which may involve multiple hits and multiple targets of variable sizes giving a constant G value of 1.66. Target analysis appears to be modified by slow recovery of activity when irradiated enzyme is brought to aqueous phase. However, pattern of irradiation at a dose of 1 x 10(5) to 8 x 10(5) Gy reveals that though binding affinity of enzyme to the substrate (hyaluronic acid) increases as shown by declining Km from 500 mg/l to 300-70 mg/l, the reaction rate of catalysis by irradiated HDase is decreased due to decrease in reaction velocity (Vmax: 266 versus 76 units at 8 x 10(5) Gy). Activation analysis of heat denaturation of nonirradiated HDase suggested the involvement of 78 kcal/mole of energy of activation (E*a) which declined to 63-52 k cal/mole after irradiation at 1 x 10(5) to 8 x 10(5) Gy for residual enzyme. The corresponding change in entropy of activation (delta S*) increased from a control value of -291 eu to -236 eu at 8 x 10(5) Gy. From thermodynamic analysis in association with recovery in aqueous phase, it is concluded that HDase is inactivated due to dissipation of proton energy among weak forces including H bonds associated with secondary/tertiary structure of molecules.

Possible role of calcium in the cardiovascular effects of prolonged administration of gamma-HCH (lindane) in rats.

Gamma-HCH (lindane) administered for long durations is reported to cause toxic cardiovascular effects. Present study was carried out to assess the changes in cardiovascular activity and cellular calcium homeostatic mechanisms in rats administered 3 mg kg-1 day-1 of gamma-HCH p.o. for 6 weeks. The changes in electrocardiogram were marked by a decrease in R-R interval and the amplitude of the P wave by 53% and 50%, respectively. The amplitude of R and T waves was increased by 65% and 58%, respectively. Calcium-45 influx was increased in atrial trabeculae (33%) and in papillary muscle (10%). The plasma calcium concentration was increased (32%) and Ca,K-ATPase activity in heart was decreased (50%). It is suggested on the basis of these findings that cellular calcium homeostatic mechanisms are involved in the cardiovascular effects of gamma-HCH administered chronically in rats.

Renal toxicity after oral administration of lead acetate during pre- and post-implantation periods: effects on trace metal composition, metallo-enzymes and glutathione.

The present study was undertaken to compare the effects of 10-50 mg/kg b.wt. of Pb acetate after chronic treatment through oral gavage on: (a) the distribution of trace elements such as Fe, Cu, Zn, and Mn, (b) enzyme activity of delta-amino levulinic acid dehydratase (delta-ALAD) and alkaline phosphatase, and (c) glutathione (GSH) in kidney and (d) delta-ALAD in blood of pregnant and non-pregnant mice. Treatment with Pb acetate was given on every alternate day for 4 weeks prior to mating and for 3-4 weeks until pregnancy became apparent and confirmed by laporatomy. Lead administration reduced the rate of reproduction as assessed by number of living viable embryos. During normal pregnancy renal Cu, Fe and GSH tended to decline although non-significantly and continued to do so after lead administration. Mn was considerably and significantly elevated, whereas activity of delta-ALAD (non-activated) was quite low in pregnant mice. Following administration of Pb acetate, kidneys of pregnant and non-pregnant dams accumulated Pb in a dose-dependent manner, but as compared to non-pregnant mice, Pb increase in pregnant dams was significantly lower. Pb toxicity was associated with the loss of delta-ALAD in blood and kidney, but unlike the non-activated form of delta-ALAD, the dithiothreitol-activated form of delta-ALAD declined in a significant amount. The residual activity showed a high degree of negative correlation with endogenous Pb as well as with Zn/Pb ratio. Pb toxicity did not modify renal Fe, Cu, and Zn in the pregnant state, but reduced renal Fe during pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoimmune-like activity of sperm specific LDH: a pathophysiological and electron microscopic study of atrophied testis and epididymis.

Hyper-immunization of male mice with human LDH-C4 evoked autoimmune reactions illustrated by the loss of LDH activity, associated histopathological changes in testes and epididymis and induction of sterility in mice. This was substantiated by the altered morphology of sperm mitochondria and plasma membrane, and by reduced number of cytoplasmic droplets as observed by electron microscopy. However, the presence of lymphoblasts and other lymphoid cells in testes indicated that the testicular damage is accentuated by activated T lymphocytes. It is concluded that immunization with human LDH-C4 produces lesions in mouse testis and epididymis, which are similar to experimentally induced autoimmune orchitis.