The Remove-the-Mask Open-Source head and neck Surface-Guided radiation therapy system

Background and Purpose

Surface Guided Radiotherapy (SGRT) for head and neck radiotherapy is challenging as obstructions are common and non-rigid facial motion can compromise surface accuracy. The purpose of this work was to develop and benchmark the Remove the Mask (RtM) SGRT system, an open-source system especially designed to address the challenges faced in radiotherapy of head and neck cancer.

Materials and Methods

The accuracy of the RtM SGRT system was benchmarked using a head phantom positioned on a robotic motion platform capable of sub-millimetre accuracy which was used to induce unidirectional shifts and to reproduce three real head motion traces. We also assessed the accuracy of the system in ten humans volunteers. The ground truth motion of the volunteers was obtained using a commercial motion capture system with an accuracy < 0.3 mm.

Results

The mean tracking error of the RtM SGRT system for the ten volunteers was of -0.1 ± 0.4 mm -0.6 ± 0.6 mm and 0.3 ± 0.2 mm, and 0.0 ± 0.2° 0.0 ± 0.1° and 0.0 ± 0.2° for translations and rotations along the left-right, superior-inferior and anterior-posterior axes respectively and we also found similar results in measurements with the head phantom. Forced facial motion was associated with lower tracking accuracy. The RtM SGRT system achieved submillimetre accuracy.

Conclusion

The RtM SGRT system is a low-cost, easy to build and open-source SGRT system that can achieve an accuracy that meets international commissioning guidelines. Its open-source and modular design allows for the development and easy translation of novel surface tracking techniques.

The first clinical implementation of real-time 6 degree-of-freedom image-guided radiotherapy for liver SABR patients

PURPOSE

Multiple survey results have identified a demand for improved motion management for liver cancer IGRT. Until now, real-time IGRT for liver has been the domain of dedicated and expensive cancer radiotherapy systems. The purpose of this study was to clinically implement and characterise the performance of a novel real-time 6 degree-of-freedom (DoF) IGRT system, Kilovoltage Intrafraction Monitoring (KIM) for liver SABR patients.

METHODS/MATERIALS

The KIM technology segmented gold fiducial markers in intra-fraction x-ray images as a surrogate for the liver tumour and converted the 2D segmented marker positions into a real-time 6DoF tumour position. Fifteen liver SABR patients were recruited and treated with KIM combined with external surrogate guidance at three radiotherapy centres in the TROG 17.03 LARK multi-institutional prospective clinical trial. Patients were either treated in breath-hold or in free breathing using the gating method. The KIM localisation accuracy and dosimetric accuracy achieved with KIM + external surrogate were measured and the results were compared to those with the estimated external surrogate alone.

RESULTS

The KIM localisation accuracy was 0.2±0.9 mm (left-right), 0.3±0.6 mm (superior-inferior) and 1.2±0.8 mm (anterior-posterior) for translations and -0.1◦±0.8◦ (left-right), 0.6◦±1.2◦ (superior-inferior) and 0.1◦±0.9◦ (anterior-posterior) for rotations. The cumulative dose to the GTV with KIM + external surrogate was always within 5% of the plan. In 2 out of 15 patients, >5% dose error would have occurred to the GTV and an organ-at-risk with external surrogate alone.

CONCLUSIONS

This work demonstrates that real-time 6DoF IGRT for liver can be implemented on standard radiotherapy systems to improve treatment accuracy and safety. The observations made during the treatments highlight the potential false assurance of using traditional external surrogates to assess tumour motion in patients and the need for ongoing improvement of IGRT technologies.

The dosimetric error due to uncorrected tumor rotation during real-time adaptive prostate stereotactic body radiation therapy

BACKGROUND

During prostate stereotactic body radiation therapy (SBRT), prostate tumor translational motion may deteriorate the planned dose distribution. Most of the major advances in motion management to date have focused on correcting this one aspect of the tumor motion, translation. However, large prostate rotation up to 30° has been measured. As the technological innovation evolves toward delivering increasingly precise radiotherapy, it is important to quantify the clinical benefit of translational and rotational motion correction over translational motion correction alone.

PURPOSE

The purpose of this work was to quantify the dosimetric impact of intrafractional dynamic rotation of the prostate measured with a six degrees-of-freedom tumor motion monitoring technology.

METHODS

The delivered dose was reconstructed including (a) translational and rotational motion and (b) only translational motion of the tumor for 32 prostate cancer patients recruited on a 5-fraction prostate SBRT clinical trial. Patients on the trial received 7.25 Gy in a treatment fraction. A 5 mm clinical target volume (CTV) to planning target volume (PTV) margin was applied in all directions except the posterior direction where a 3 mm expansion was used. Prostate intrafractional translational motion was managed using a gating strategy, and any translation above the gating threshold was corrected by applying an equivalent couch shift. The residual translational motion is denoted as T r e s $T_{res}$ . Prostate intrafractional rotational motion R u n c o r r $R_{uncorr}$ was recorded but not corrected. The dose differences from the planned dose due to T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ , ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) and due to T r e s $T_{res}$ alone, ΔD( T r e s $T_{res}$ ), were then determined for CTV D98, PTV D95, bladder V6Gy, and rectum V6Gy. The residual dose error due to uncorrected rotation, R u n c o r r $R_{uncorr}$ was then quantified: Δ D R e s i d u a l $\Delta D_{Residual}$ = ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) - ΔD( T res ${T}_{\textit{res}}$ ).

RESULTS

Fractional data analysis shows that the dose differences from the plan (both ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) and ΔD( T r e s $T_{res}$ )) for CTV D98 was less than 5% in all treatment fractions. ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) was larger than 5% in one fraction for PTV D95, in one fraction for bladder V6Gy, and in five fractions for rectum V6Gy. Uncorrected rotation, R u n c o r r $R_{uncorr}$ induced residual dose error, Δ D R e s i d u a l $\Delta D_{Residual}$ , resulted in less dose to CTV and PTV in 43% and 59% treatment fractions, respectively, and more dose to bladder and rectum in 51% and 53% treatment fractions, respectively. The cumulative dose over five fractions, ∑D( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) and ∑D( T r e s $T_{res}$ ), was always within 5% of the planned dose for all four structures for every patient.

CONCLUSIONS

The dosimetric impact of tumor rotation on a large prostate cancer patient cohort was quantified in this study. These results suggest that the standard 3-5 mm CTV-PTV margin was sufficient to account for the intrafraction prostate rotation observed for this cohort of patients, provided an appropriate gating threshold was applied to correct for translational motion. Residual dose errors due to uncorrected prostate rotation were small in magnitude, which may be corrected using different treatment adaptation strategies to further improve the dosimetric accuracy.

Elastic Scattering and Reaction Cross-section of 8Li on 209Bi

Nuclear physics in the 21st century is driven by a quest to understand the properties of ever more exotic nuclear systems. Unusual structural phenom- ena are observed to arise in light weakly bound nuclei such as 8Li. 8Li has a cluster structure core of 7Li surrounded by a loosely bound neutron which is observed to influence reaction mechanisms near the fusion barrier. Elastic scat- tering provides a vital step towards understanding more complicated reaction mechanisms. In this work, elastic scattering was measured for 8Li + 2°9Bi at energies 2% to 34% above the barrier, allowing extraction of reaction cross- sections. The systematics of the reaction cross-sections of 8Li compared to neighbouring nuclei 6,7,9,11Li are discussed.

Systematic Study of Quasifission in 48Ca-induced reactions

The production of superheavy elements through the fusion of two heavy nuclei is severely hindered by the quasifission process, which results in the fission of heavy systems before an equilibrated compound nucleus (CN) can be formed. The heaviest elements have been synthesised using 48Ca as the projectile nucleus. However, the use of 48Ca in the formation of new superheavy elements has been exhausted, thus a detailed understanding of the properties that made 48Ca so successful is required. Measurements of mass-angle distributions allow fission fragment mass distribution widths to be determined. The effect of the orientation of prolate deformed target nuclei is presented. Closed shells in the entrance channel are also shown to be more important than the stability of the formed CN in reducing the quasifission component, with reduced mass widths for reactions with the closed shell target nuclei 144Sm and 208Pb. Comparison to mass widths for 48Ti-induced reactions show a significant increase in the mass width compared to 48Ca-induced reactions, highlighting the difficulty faced in forming new superheavy elements using projectiles with higher atomic number than 48Ca.

Mechanisms Suppressing Superheavy Element Yields in Cold Fusion Reactions

Superheavy elements are formed in fusion reactions which are hindered by fast nonequilibrium processes. To quantify these, mass-angle distributions and cross sections have been measured, at beam energies from below-barrier to 25% above, for the reactions of ^{48}Ca, ^{50}Ti, and ^{54}Cr with ^{208}Pb. Moving from ^{48}Ca to ^{54}Cr leads to a drastic fall in the symmetric fission yield, which is reflected in the measured mass-angle distribution by the presence of competing fast nonequilibrium deep inelastic and quasifission processes. These are responsible for reduction of the compound nucleus formation probablity P_{CN} (as measured by the symmetric-peaked fission cross section), by a factor of 2.5 for ^{50}Ti and 15 for ^{54}Cr in comparison to ^{48}Ca. The energy dependence of P_{CN} indicates that cold fusion reactions (involving ^{208}Pb) are not driven by a diffusion process.

Origins of Incomplete Fusion Products and the Suppression of Complete Fusion in Reactions of ^{7}Li

Above-barrier complete fusion involving nuclides with low binding energy is typically suppressed by 30%. The mechanism that causes this suppression, and produces the associated incomplete fusion products, is controversial. We have developed a new experimental approach to investigate the mechanisms that produce incomplete fusion products, combining singles and coincidence measurements of light fragments and heavy residues in ^{7}Li+^{209}Bi reactions. For polonium isotopes, the dominant incomplete fusion product, only a small fraction can be explained by projectile breakup followed by capture: the dominant mechanism is triton cluster transfer. Suppression of complete fusion is therefore primarily a consequence of clustering in weakly bound nuclei rather than their breakup prior to reaching the fusion barrier. This implies that suppression of complete fusion will occur in reactions of nuclides where strong clustering is present.

Sarcoptic mange in wombats-A review and future research directions

Sarcoptic mange is caused by the mite Sarcoptes scabiei and has recently been recognized as an emerging infectious disease of wildlife worldwide. The mite is one of the main causes of population decline in southern hairy-nosed (Lasiorhinus latifrons) and bare-nosed wombats (Vombatus ursinus). This review focuses on Sarcoptes scabiei infestations in wombats and provides insights into why the disease may be so prevalent in wombats. Current treatment practices and trials conducted in the field to reduce the incidence of sarcoptic mange in wombats are described and critically reviewed. Current and potential future avenues of research are discussed.

Antigenaemia and antibody response to Toxoplasma gondii in human immunodeficiency virus-infected patients

Toxoplasma encephalitis in immunocompromised patients results from reactivation of previously acquired (latent) infection. The aim of the study is to assess the antigenaemia and antibody response to Toxoplasma gondii in human immunodeficiency virus (HIV)-infected patients to determine the best marker for early diagnosis of toxoplasmosis in such patients. Indirect enzyme-linked immunosorbent assay (ELISA) for detection of IgG, IgM and IgA anti-toxoplasma antibodies and double-sandwich ELISA for toxoplasma antigen is carried out in serum samples collected from 100 HIV seropositive patients and 75 controls. Toxoplasma-specific IgG, IgM and IgA antibody response and antigenaemia were detected in 12%, 6%, 7% and 14% of HIV-infected patients, respectively. On retrospective analysis of 14 patients with antigenaemia only one had central nervous system (CNS) symptoms attributable to toxoplasma infection. In this patient, the CD4+ cell count was below 50/microL and none of the specific immunoglobulin isotype responses could be detected. The patient showed clinical improvement following specific chemotherapy for toxoplasmosis. In 25 HIV-negative and anti-toxoplasma IgG antibody-positive controls, IgM was detected in two (8%), IgA in five (20%) and antigenaemia in 10 (40%), while 50 HIV seronegative healthy controls were negative for both antigen and antibody responses. The study indicates that detection of toxoplasma antigen in addition to IgG antibody response may prove to be a useful indicator in the early diagnosis of reactivated toxoplasmosis in HIV/AIDS patients.

Current knowledge on the distribution of arsenic in groundwater in five states of India

Testing of groundwater used for drinking for arsenic has been undertaken more widely by state governments in several states of India in recent years with the support of UNICEF. Available data for five states are collated in this paper and this provides the most up-to-date picture of areas known to be affected by arsenic in groundwater in the Indian portion of the Ganges-Brahmaputra river basin. In West Bengal, water from 132,262 government installed handpumps in 8 districts has been tested and overall 25.5% of samples were found to contain arsenic at concentrations greater than 50 microgL(-1) and 57.9% at concentrations greater than 10 microgL(-1). On the banks of the Brahmaputra in Assam, to date, samples from 5,729 government handpump sources in 22 districts have been tested for arsenic. Overall, samples from 6.3% of sources were found to contain arsenic at concentrations greater than 50 microgL(-1) and 26.1% at concentrations greater than 10 microgL(-1). In Bihar, on the River Ganges upstream of West Bengal, 66,623 sources from 11 districts have been tested and water samples from 10.8% of sources were found to contain arsenic at concentrations greater than 50 microgL(-1) and 28.9% at concentrations greater than 10 microgL(-1). Upstream of Bihar in Uttar Pradesh, home of the Taj Mahal, to date water samples from 20,126 government-installed handpump sources have been tested. As a result 2.4% of the samples tested were found to contain arsenic at concentrations greater than 50 microgL(-1) and 21.5% at concentrations greater than 10 microgL(-1). Finally in one district of Jharkhand, lying on the Ganges alluvial plain between Bihar and West Bengal, 9,007 sources have been tested and water samples from 3.7% of sources were found to contain arsenic at concentrations greater than 50 microgL(-1) and 7.5% at concentrations greater than 10 microgL(-1). State governments have adopted different sampling strategies and these are described in this paper. Testing is ongoing in several states and the complete picture is yet to emerge in some areas.

Antigenaemia and antibody response to Leishmania donovani stage-specific antigens and rk39 antigen in human immunodeficiency virus-infected patients

In order to define the possible markers for the early diagnosis of asymptomatic visceral leishmaniasis in human immunodeficiency virus (HIV)-infected individuals, the antigenaemia and antibody response to stage-specific Leishmania donovani and rk39 antigens is assessed by enzyme-linked immunosorbent assay (ELISA) and immunoreactivity to stage-specific antigens analysed by Western blot. Serum samples from two out of 100 HIV-infected individuals were found positive for antigenaemia, antibody response to stage-specific L. donovani antigens and rk39 antigen, and one sample was also positive for antigenaemia and antibody response to L. donovani antigens, while antibody detection to rk39 antigen was not carried on this sample. Additionally, one sample was found positive for amastigote antigenaemia and antibody response to amastigote antigen, while in this patient promastigote antigenaemia and antibody response to promastigote L. donovani and rk39 antigen could not be detected. One sample was found positive for antigenaemia, antibody response to amastigote antigen and negative for antibody response to promastigote antigen, while in this patient response to rk39 antigen was borderline. Although antibody response to rk39 antigen could be detected in 9/88 (10%) HIV-infected individuals, in six of these nine patients neither antigenaemia nor antibody response to stage-specific L. donovani antigens could be detected. All 10 confirmed visceral leishmaniasis and HIV-negative control patients had positive antigenaemia and antibody response to L. donovani amastigote and promastigote antigens, while all the normal healthy individuals were negative. The study indicated that detection of antibody response to rk39 antigen, amastigote antigenaemia and antibody response to amastigote antigen may prove to be better markers than detection of promastigote antigenaemia, antibody response to promastigote antigen and immunoblot reactivity.

Exploring effects of different antioxidants on dexamethasone-induced lipid peroxidation using common laboratory markers

As a part of our ongoing effort to explore drug-induced lipid peroxidation in relation to drug-induced toxicity, our recent observations on lipid peroxidation induction potential of dexamethasone, a commonly used glucocorticoid compound in inflammatory and allergic conditions, has been presented considering lipid peroxidation a possible mediator of toxicity. An attempt was made to see the suppressive actions of some conventional antioxidant compounds, viz, ascorbic acid, alpha-tocopherol and probucol on dexamethasone-induced lipid peroxidation. It was found from the study that dexamethasone increased malondialdehyde content vis-a-vas decreased the level of reduced glutathione significantly in the liver homogenate. This suggests that dexamethasone caused a significant extent of lipid peroxidation which may be related to the toxic potential of the drug. It was further found all of the above antioxidants could suppress dexamethasone-induced lipid peroxidation to the significant extent.

QSAR of matrix metalloproteinase inhibitor N-[(substituted phenyl)sulfonyl]-N-4-nitrobenzylglycine hydroxamates using LFER model

QSAR analyses of matrix metalloproteinase (MMP) inhibitor N-[(substituted phenyl)sulfonyl]-N-4-nitrobenzylglycine hydroxamates, recently reported by Scozzafava and Supuran, have been attempted using linear free energy related (LFER) model of Hansch to explore the contribution patterns of the phenyl ring substitutions (P1' anchoring site of the ligands) to the activities against MMP-1, -2, -8 and -9 (pC1, pC2, pC, and pC9) and C. histolyticum collagenase (pC(ChC)) and also to find out relations among the activities. Multiple regression analyses applied on the data set reveal that electron withdrawing meta substituents and lipophilic ortho and meta substituents are conducive to pC1 while presence of substituents (larger than hydrogen) at vicinal positions on the phenyl ring and bulkier ortho substituents are detrimental to the activity. Again, the electronic and steric parameters of meta substituents (sigmam and MRm) and lipophilicity parameter of ortho substituents (pio) contribute significantly to pC2, pC8 and pC9: sigmam shows parabolic relationships (optimum sigmam values being 0.518, 0.584 and 0.522 respectively) and steric bulk of meta substituents has negative impact while presence of hydrophilic groups at the ortho positions increases the activities. Further, presence of electron withdrawing meta substituents and hydrophilic para substituents is conducive to the C. histolyticum collagenase (pC(ChC)) activity. The study suggests that the structural and physicochemical requirements of the P1' anchoring site for the activities against MMP-2, -8 and -9 are highly intercorrelated and these are comparatively less correlated with those for the activities against MMP-1 and C. histolyticum collagenase.

Evaluation of alpha-tocopherol, probucol and ascorbic acid as suppressors of digoxin induced lipid peroxidation

Protective effects of three free radical scavengers, tocopherol (TOC), probucol (PR) and ascorbic acid (AA), on cardiotonic glycoside digoxin (DIG) induced lipid peroxidation in goat liver homogenate, have been studied by measuring malondialdehyde and glutathione contents as indicator parameters. The level of reduced glutathione decreased vis-a-vis malondialdehyde content increased in the drug treated samples in comparison with the controls. This suggests that DIG may have significant lipid peroxidation induction capacity. Considering lipid peroxidation as a toxicity mediating process, this may be related to the toxic potential of the drug. When the liver homogenate samples were incubated with antioxidant (TOC/PR/AA) in conjunction with the drug (DIG), lipid peroxidation was suppressed as indicated by increased level of reduced glutathione and decreased level of malondialdehyde in comparison with those of drug treated samples. This indicates that TOC, PR and AA may have considerable suppressive action on DIG induced lipid peroxidation. Thus, these antioxidants merit further extensive study to explore their potential in reducing DIG induced toxicity that may be mediated by free radical mediated process.

Hansch analysis of antimalarial cyclic peroxy ketals with physicochemical and electrotopological parameters

Hansch analysis of some antimalarial cyclic peroxy ketals (IV) having structural variations at the para substituted phenyl ring and an alicyclic ring of different size reveals that electronic and steric parameters of the phenyl ring substituents are important for explaining the variation in the activity while hydrophobicity parameter is of little significance. Electron withdrawing substituents with higher MR (molar refractivity) or V(W) (van der Waals volume) are preferred for the activity. Use of structural descriptors suggests that presence of a seven membered alicyclic ring attached to the peroxy bridge containing ring is conducive to the activity. Application of electrotopological state atom index (ETSAI) suggests a pharmacophore containing the peroxy bridge. This is corroborated by earlier observation on importance of oxygen atoms of the peroxy linkage of artemisinin for antimalarial activity. Although incorporation of ETSAI into Hansch model does not improve the relations, the electronic parameter sigma is found to be significantly correlated with it.

QSAR of antineoplastics IV: Hansch analysis of N-(7-indolyl)benzenesulfonamides against KB human nasopharynx carcinoma, colon 38 murine adenocarcinoma and P388 murine leukemia cell lines

Hansch analysis of recently reported antitumor activities of novel N-(7-indolyl)benzenesulfonamide derivatives against KB human nasopharynx carcinoma, colon 38 murine adenocarcinoma and P388 murine leukemia cell lines reveals that the pattern of receptor interactions in human KB cells differs from that in murine (colon 38 and P388 leukemia) cells. The latter two activities are autocorrelated and show similar receptor specificity. It seems that two binding sites, one interacting with the indole fragment and another with phenyl fragment of the indolylbenzenesulfonamide compounds, are present on the murine cell receptors (colon 38 and P388 leukemia) while only the latter binding site is active on the human KB cell receptors. For the activity against KB cells, a para-methyl or paramethoxy substituent on the phenyl ring of benzenesulfonamide moiety greatly enhances the activity. For the other two activities, a 3-chloro or 3-cyano substituent on indole nucleus enhances activities, while presence of bulkier meta or para substituent on the phenyl ring decreases activities. Presence of an ortho substituent on the phenyl ring appears to be detrimental for all the three activities. Equations generated by both QSAR and QAAR studies are quite robust as evidenced from cross-validation by 'leave-one-out' technique.

QSAR of antineoplastics V: Exploration of receptor interaction sites of antitumor N-(7-indolyl)benzenesulfonamides targeting GI phase using electrotopological state atom index

Quantitative structure activity relationship (QSAR) study of antiproliferative activities of N-(7-indolyl)benzenesulfonamides with electrotopological state atom (ETSA) index corroborates the conclusions of the previously reported Hansch analysis that the structural requirements for interactions with receptors of human KB nasopharynx cell line are different from that for murine colon 38 and P388 leukemia cell lines. The study suggests that both phenyl ring and indole moiety are the important receptor interaction sites present on the ligands for the murine cell lines, while the latter site does not appear to play significant role in case of human KB cell carcinoma.

Effects of oral contraceptive norethindrone on blood-lipid and lipid peroxidation parameters

Considering importance of the lipophilicity of norethindrone (log P=2.97), a significant contributor to its mechanism of action, interaction of the drug with total lipids of goat whole blood have been investigated using phospholipid binding, fatty acid composition and peroxidation phenomena as the parameters under investigation. The objective was to derive an insight into the pharmacodynamic behavior of the drug by correlating biological activity with drug induced changes in lipid constituents. Significant loss in phospholipid along with changes in fatty acid cotmposition was observed after incubation of whole blood with norethindrone at 56 ng/ml (effective contraceptive concentration in blood) in varying periods of time. This may be ascribed to binding affinity of norethindrone with lipid constituents in blood. Lipid binding potential of the drug may have a role in its therapeutic effect. Lipid peroxidation induction potential of norethindrone was quantitatively measured in the context of its toxicity. The results reveal that northindrone caused significant extent of lipid peroxidation. Ascorbic acid, a promising antioxidant, at equivalent human dose levels of 250 mg and 500 mg could significantly reduce norethindrone induced lipid peroxidation.

Effect of aspirin on blood-lipid interaction and lipid peroxidation phenomena in relation to partition coefficient and biological activity

Considering the lipophilicity of aspirin (log P = -1.15), a significant contributor to its action mechanism, interaction of the drug with the whole lipids of goat blood have been investigated using phospholipid binding and lipid peroxidation phenomena as the parameters under investigation. The lipid content change along with the peroxidation induced by aspirin and its suppression with ascorbic acid had been quantitatively measured. Significant loss in phospholipid was observed after incubation of whole blood with aspirin in varying periods of time. This may be ascribed to binding affinity of aspirin with lipid constituents in blood, which may have potential role in its therapeutic effect. Lipid peroxidation induction potential of aspirin caused significant extent of peroxidation. Ascorbic acid, an antioxidant could significantly reduce aspirin induced lipid peroxidation.

Ceftriaxone induced lipid peroxidation and its inhibition with various antioxidants: Part II. Evaluation of glutathione and probucol as antioxidants

Exploratory studies on drug induced lipid peroxidation in goat whole blood and its inhibition with antioxidants were carried out using sodium ceftriaxone (CTS) as the representative drug and glutathione and probucol as the representative antioxidants. The studies showed that CTS could induce lipid peroxidation to a significant extent. Lipid peroxidation is a toxicity mediating process, this finding may be correlated with the toxic potential of the drug. It was further found that glutathione and probucol caused significant suppression of CTS induced lipid peroxidation. The results suggest that glutathione and probucol merit further assessment to explore their potential to reduce drug induced lipid peroxidation and thus to increase therapeutic index of the drug by way of reducing toxicity that may be mediated through free radical mechanism.

Ethinyl estradiol: its interaction on blood-lipid

Lipophilicity (log P) of the drug plays an important role when drug reaches in the critical reaction site, i.e., active site cum receptors where the major constituent is lipid moieties. The drug molecule may be responsible for altering the lipid constituents, which is measured in terms of phosphorus content and can be explained by their fatty acid changes that are linked with biological effect of the drug. Having considered the lipophilicity of ethinyl estradiol (log P = 3.67), its interactions with the whole lipid of goat blood have been investigated along with fatty acid changes and lipid peroxidation phenomena. There was significant loss of phosphorus content of phospholipid and change of fatty acid constituents of whole lipid. This may be ascribed to binding affinity of ethinyl estradiol with lipid constituents in blood. Lipid binding potential of the drug may have role in its therapeutic effect. The peroxidation induced by drug has been quantitatively measured along with its suppression by using antioxidant. The results reveal that ethinyl estradiol caused significant extent of lipid peroxidation. Ascorbic acid, a promising antioxidant could significantly reduce drug induced lipid peroxidation.

Evaluation of glutathione and ascorbic acid as suppressors of drug-induced lipid peroxidation

In different sets of experiment lipid peroxidation induction capacity of two drugs, viz., ceftizoxime sodium, a third generation cephalosporin antibiotic, and acyclovir, an antiviral agent, was studied using goat whole blood as the lipid source. Ceftizoxime sodium caused significant extent of lipid peroxidation. Lipid peroxidation being a toxicity mediating process, such observation may be related to the toxic potential of the drug. Insignificant induction of lipid peroxidation was found in case of acyclovir and this is in good agreement with the safety record of the drug. Glutathione and ascorbic acid could significantly reduce ceftizoxime sodium induced lipid peroxidation, suggesting that free radical scavenging action of antioxidants may be exploited by possible antioxidant co-therapy to reduce iatrogenicity of the drug in persons with impaired endogenous antioxidant defence. Glutathione and ascorbic acid appear to be promising candidates for further investigation in this regard.

Effect of two cardiac glycosides, digitoxin and digoxin on blood lipids

Two cardiac glycosides, namely digitoxin and digoxin when treated with goat blood, were found to alter the lipid constitution as measured by their phosphorus content, fatty acid composition and malonaldehyde content. There was significant increase in the poly-unsaturated fatty acids (PUFA) and malonaldehyde contents in blood treated with these drugs. Possible correlation between the lipophilicity of the drugs and their biological activity is discussed.

Cysteine, a chelating moiety for synthesis of technetium-99m radiopharmaceuticals--Part IV. Benzyl cysteine and derivatives

To explore the possibility of utilizing cysteine derivatives for technetium-99m radiopharmaceutical preparation with clinical potential, we synthesized two benzyl substituted cysteine compounds, namely, S-benzyl cysteine 1 and cysteine benzyl ester 3. It was expected, from our previous studies on benzoyl cysteines, that the above two ligands after chelation with 99mTc would be excreted by the hepatobiliary pathway. Although for 99mTc-3 the above expectation was realized, 99mTc-1 behaved in a most unexpected way by affixing itself with kidney and selecting the renal tubular secretory pathway for its excretion. It is anticipated that the affinity of 99mTc-1 for kidney is due to its interaction with the kidney sulphhydryl group and it also formed an adduct with other sulphydryl containing compounds like thiophenol. In terms of the kidney-to-background ratio, 99mTc-1 showed some superiority over other kidney structure agents, like 99mTc-dimercaptosuccinic acid and 99mTc-glucoheptanoic acid and, therefore, the chelate (99mTc-1) may have the potential to replace the above two radiopharmaceuticals in clinical use.

Effect of propranolol hydrochloride on blood cell lipids in relation to partition coefficient and biological activity

Considering the high lipophilicity of propranolol (log P = 3.56), its interactions with the cell membrane lipids of goat blood have been investigated. It is observed that lipid loss after incubation of blood cells with propranolol hydrochloride in salt glucose medium for varying periods of time was accompanied with significant increases in PUFAs. Amongst the PUFAs studied the omega 3 and omega 6 fatty acids, the two important precursors of eicosenoids, have shown increase in varying amounts. This phenomenon is presumably responsible for the significant cardiovascular activity of this drug.

Correlation of phospholipid loss in goat whole blood with solvochromic properties of antiamebics like emetine, metronidazole and diloxanide furoate

Phospholipid content of whole blood lipid decreases significantly when goat blood is incubated for different length of time with different amebicidal agents (e.g., emetine, metronidazole and diloxanide furoate). The plots of relative per cent phosphate loss against incubation period show biphasic nature and suggest that the rates of phospholipid loss bears some relation with the drug's lipophilicity (log P in 1 octanol/water system). The absolute phospholipid loss seems to be governed by the drug's aquasolubility. Implication of these finding were discussed in terms of their clinical profiles assuming that the loss of phospholipid is due to drug's binding with the phospholipid layer in amebic cyst-coat, being the first step which may trigger a chain of events leading to the onset of drug action.

Effect of lignocaine on blood lipid in relation to partition coefficient and biological activity

To correlate lipophilicity of lignocaine with changes in lipid composition of blood as a result of in vitro incubation with the drug, phosphorus content and fatty acid compositions of blood lipids before and after lignocaine treatment have been compared with those of a standard phospholipid, lecithin, under similar conditions of drug treatment. The change in fatty acid constituents has been correlated with the biological activity (both therapeutic and toxic) of lignocaine.

Synthesis, glycosylation and rapid secretion of a glycoprotein by Achlya, a primitive eucaryote

Achlya ambisexualis, a water mold, secretes several glycoproteins during exponential growth. Among these is a major protein of 39 000 daltons (protein A-39) which is secreted very rapidly. Protein A-39 is detected among the soluble cellular proteins labeled for 5 min. However, after longer labeling times, an additional 95 000 dalton glycoprotein was immunoprecipitated from among the cytoplasmic proteins by antiserum against protein A-39. This antiserum reacted with a single 37 000 dalton protein from the in vitro translation products of poly(A)-containing RNA in a wheat germ cell-free system which is cleaved to a faster moving component in the presence of dog pancreatic membranes. Immunoprecipitated, chain-completion products of polysomes also show a 37 000 dalton peptide which does not bind to lectins, indicating absence of co-translational cleavage and glycosylation. Tunicamycin inhibits the appearance of the 95 000 dalton protein. Several immunoprecipitable proteins, including protein A-39, having sizes identical to the secretory proteins accumulate in the cytoplasm in the presence of this inhibitor. A short pulse with [3H]glucosamine followed by a chase showed that incorporation in protein A-39 increases while that in 95 000 dalton protein is decreasing. These results suggest that the 95 000 dalton glycoprotein may serve as a glycosyl donor to secretory protein A-39.

Post-translational processing of 7S and 11S components of soybean storage proteins

The synthesis and processing of the major storage proteins in soybean cotyledons was studied both in vivo and in vitro. The α and α' subunits of 7S as well as the 11S proteins are synthesized as higher molecular weight-precursors on membrane-bound polysomes. The initial translation products of the 7S are proteolytically cleaved during translation suggesting the removal of a 'signal peptide' as evidenced by the presence of 2α and 2α' peptides immunoreactive with 7S antibody in the in vitro chain completion products of the membrane-bound polysomes. This is followed or accompanied by cotranslational glycosylation, which increases their size equivalent to that of initially-synthesized precursors. In vivo pulse-labelled 7S α and α' products are of slightly higher molecular weights than the immunoprecipitable chain-completion products, indicating further post-translational modifications. A slow post-translational processing during a period of 1.5 to 16 h yields the final 7S α and α' glycoproteins.Acidic and basic subunits of the 11S protein appear to be synthesized from common large molecular weight (60K-59K) precursors. Antibodies to the 11S acidic component recognize both acidic and basic domains in the precursor while those raised against basic subunits appear to be specific for that region only. The processing of the 11S precursor is also very slow and occurs post-translationally. This slow rate of processing, coupled with a temporal difference in the synthesis of 7S and 11S components, suggests a highly coordinated mechanism for synthesis and packaging of these proteins into protein bodies during seed development.

[Carnitine deficiency myopathy (author's transl)]

Carnitine is a carrier for the transport of long-chain fatty acids from the cytoplasmic to the mitochondrial space. So far 18 cases of carnitine deficiency myopathy have been recognized, generally occurring as progressive or relapsing myopathy. In contrast episodic exercise-induced myalgia and paresis was found in a 46-year-old patient with carnitine deficiency myopathy which was quickly reversible at rest. As a consequence of this observation carnitine deficiency myopathy must be added to the differential diagnosis of the McArdle syndrome (muscular phosphorylase deficiency) and other "exercise myopathies".