Phase II clinical trial of a vas deferens injectable contraceptive for the male

Following up on an earlier clinical trial demonstrating the safety of an intra-vas deferens injection of a contraceptive drug named Risug, comprised of styrene maleic anhydride (SMA) in a solvent vehicle of dimethylsulphoxide (DMSO), a study to assess the contraceptive effectiveness of a specific dose (60 mg) of SMA bilaterally was planned and implemented. Male subjects and their wives with normal reproductive profiles were the volunteer subjects. The wives were not using any contraceptives. The results reconfirm the safety and show that for a period of at least 1 year, the treatment leads to azoospermia in the male and gives pregnancy protection.

Production and physiological actions of anandamide in the vasculature of the rat kidney

The endogenous cannabinoid receptor agonist anandamide is present in central and peripheral tissues. As the kidney contains both the amidase that degrades anandamide and transcripts for anandamide receptors, we characterized the molecular components of the anandamide signaling system and the vascular effects of exogenous anandamide in the kidney. We show that anandamide is present in kidney homogenates, cultured renal endothelial cells (EC), and mesangial cells; these cells also contain anandamide amidase. Reverse-transcriptase PCR shows that EC contain transcripts for cannabinoid type 1 (CB1) receptors, while mesangial cells have mRNA for both CB1 and CB2 receptors. EC exhibit specific, high-affinity binding of anandamide (Kd = 27.4 nM). Anandamide (1 microM) vasodilates juxtamedullary afferent arterioles perfused in vitro; the vasodilation can be blocked by nitric oxide (NO) synthase inhibition with L-NAME (0.1 mM) or CB1 receptor antagonism with SR 141716A (1 microM), but not by indomethacin (10 microM). Anandamide (10 nM) stimulates CB1-receptor-mediated NO release from perfused renal arterial segments; a similar effect was seen in EC. Finally, anandamide (1 microM) produces a NO-mediated inhibition of KCl-stimulated [3H]norepinephrine release from sympathetic nerves on isolated renal arterial segments. Hence, an anandamide signaling system is present in the kidney, where it exerts significant vasorelaxant and neuromodulatory effects.

Reverse Micelle Formation of Triton X-100 in Butanol and n-Heptane Mixed Solvents Studied by the Positron Annihilation Technique

The positron annihilation technique (PAT) has been applied to study the molecular association phenomenon of Triton X-100 (TX-100) and formation of reversed micelles in the mixed solvent of butanol and n-heptane. The results indicate the sensitivity of positronium (Ps) parameters to the phase transition region due to the self-aggregation phenomenon of TX-100 within the system. The intensity of the long-lived ortho-Ps component, I3, and its lifetime, tau3, show a remarkable change at a critical concentration of the surfactant at approximately 1.5 mM coined as the operational CMC of TX-100 in both (1:1) and (1:2) butanol-n-heptane (BuHp) systems. The narrow component/para-Ps intensity as computed from Doppler broadening of annihilation radiation indicates discernable changes at the same concentration region ( approximately 1.5 mM) of TX-100 in the system. Further, microphase changes due to the association of water molecules within the nonaqueous phase has been studied by Ps parameters, which reveals a clear demarcation of the polar and nonpolar zones.

Replacement of serum and hormone additives with follicular fluid in the IVM medium: Effects on maturation, fertilization and subsequent development of buffalo oocytes in vitro

Buffalo follicular fluid was used in the IVM medium in place of serum and hormone additives for stimulating nuclear and cytoplasmic maturation of buffalo oocytes in vitro. Follicular fluid (buFF) was aspirated from visible surface follicles from buffalo ovaries. Cumulus oocyte complexes (COCs) were matured for 24 to 26 h at 38.5 degrees C, 5% CO(2) in air in the maturation medium (TCM-199). When used, the concentration of fetal bovine serum (FBS) was 10% and that of FSH-P was 5 mug/ml. In Experiment 1 TCM-199 was supplemented with 1) FBS, 2) FBS + FSH-P, 3) 20% buFF and 4) 40% buFF. The matured oocytes were denuded and stained with Giemsa stain to study nuclear maturation. The proportion of oocytes which completed nuclear maturation was similar in medium containing FSH (74%) and 20 or 40% buFF (67%), which was higher (P < 0.05) than in medium with FBS but without FSH or buFF (47%). In Experiment 2, which was aimed at examining the effects of buFF on cumulus expansion and rates of fertilization and subsequent development to the blastocyst stage after IVF, the maturation medium was supplemented with 1) FBS + FSH-P, 2) 20% buFF and 3) 40% buFF. The COCs matured in medium containing 20 or 40% buFF had significantly higher (P < 0.01) cumulus expansion than those matured in medium with FBS + FSH-P. Of the COCs matured in medium with FBS + FSH-P and 20 or 40% buFF, the fertilization rates indicated by the incidence of cleavage (56, 51 and 52%, respectively) and the proportion of cleaved COCs developing to morula (58, 54 and 57%, respectively) and blastocyst stage (30, 31 and 35%, respectively) were not significantly different. In Experiment 3, supplementation of the maturation medium with 1) FBS + FSH-P and 2) FBS + FSH-P + 20% buFF resulted in similar rates of morulae (41 and 38%, respectively) and blastocysts (31 and 25%, respectively), indicating that simultaneous presence of FBS, FSH-P and buFF did not have an additive effect on embryo yield. The results show that the gonadotropin and serum source in the IVM medium can be replaced by buFF at the 20% level to achieve comparable morula and blastocyst yields.

The occurrence of beta-thalassemia mutation and its interaction with hemoglobin E in the eastern India

The distribution of variant hemoglobin in India has been related to various ethnic groups among other factors. beta-Thalassemia is the most frequent monogenic disorder in the country. Analysis of hemoglobin of 435 cases from Eastern India was performed by electrophoresis and by other quantitative methods. Analysis of the beta-globin gene of 112 cases used ARMS (amplification refractory mutation system)-PCR (polymerase chain reaction) techniques showing that IVS-1 nt 5 (G-->C) is the most prevalent mutation in populations from Eastern India. IVS-1 nt 5 (G-->C) interacts with the codon 26 (G-->A) mutation to produce E beta-thalassemia phenotype in the samples from West Bengal, India.

Pattern of motor neurone disease in eastern India

A clinical study about the pattern of motor neurone disease in eastern India was carried out from July 1993 to June 1995 at Bangur Institute of Neurology, Calcutta and SSKM Hospital, Calcutta. A total of 110 cases were studied and they constituted 0.11% of all neurological cases seen in the general OPD. Of 110 cases, amyotropic lateral sclerosis (ALS) constituted 43.6%, progressive muscular atrophy (PMA) 10.9%, post-polio progressive muscular atrophy (PPMA) 1.8%, spinal muscular atrophy (SMA) 20%, atypical form Madras pattern of MND (MMND) 0.9% and monomelic amyotrophy (MMA) 22.7% of cases. Disease is more common in males than females and average duration of symptoms before presentation varied from 1 to 12 months. Most of the patients were either agricultural labourers or manual workers in ALS variety whereas MMA variety was evenly distributed in both hard labourers and sedentary workers. Most of the patients in MMA and SMA groups presented before 30 years of age whereas ALS and PMA group presented after 30 years. Trauma was the commonest antecedent event in ALS and MMA followed by electrocution in the same two groups. Family history was found to be absent in SMA group though the disease is considered as a hereditary one. Weakness of the limbs and wasting of the muscles were common presenting symptoms and signs. Bulbar symptoms and signs were found only in the ALS group. EMG showed neurogenic pattern and mixed pattern in most of the patients in all groups. Only a few patients showed myopathic pattern. Neuroimaging study helped in exclusion of compressive lesion excepting two cases of MMA where facetal hypertrophy was present. Monomelic amyotrophy, a special variety of motor neurone disease, is not rare in this part as compared to other parts of India and Asia.

Ontogeny of neurotransmitter amino acids in human fetal brains

A wide spectrum of developmental profiles is presented for a few important neurotransmitter amino acids, namely gamma-aminobutyric acid, glycine, glutamic acid, aspartic acid and taurine as well as the key enzymes involved in their metabolism in human fetal brains of different gestational ages. Besides taurine almost all these amino acids and their key metabolic enzymes were found to be progressively enhanced upto the mid period of third trimester of pregnancy indicating a rapid growth of nerve processes, myelination and maturation of fetal brains particularly during this period. Interestingly taurine showed an inverse relationship of ontogenic pattern with respect to its biosynthesizing enzyme in fetal brains.

Selection of coplanar or noncoplanar beams using three-dimensional optimization based on maximum beam separation and minimized nontarget irradiation

PURPOSE

The design of an appropriate set of multiple fixed fields to achieve a steep dose gradient at the tumor edge, with minimal normal tissue exposure, is a very difficult problem, since a virtually infinite number of possible beam orientations exists. In practice we have selected beams in an iterative and often time-consuming process. This work proposes an optimization method, based on geometric and dose elements, to effectively arrive at a set of beam orientations.

METHODS AND MATERIALS

Beams are selected by minimizing a goal function including an angle function (beam separation for steep dose gradient at target edge) and a length function (related to normal tissue dose volume histogram). The relative importance of these two factors may be adjusted depending on the clinic situation. The model is flexible and can include case specific practical anatomic and physical considerations.

RESULTS

In extremely simple situations, the goal function yields results consistent with well-known analytical solutions. When applied to more complex clinical situations, it provides clinically reasonable solutions similar to those empirically developed by the clinician. The optimization process takes approximately 25 min on a UNIX workstation.

CONCLUSION

The optimization scheme provides a practical means for rapidly designing multiple field coplanar or noncoplanar treatments. It overcomes limitations in human three-dimensional visualization such as trying to visualize beam directions and keeping track of the hinge angle between beams while accounting for anatomic/machine constraints. In practice, it has been used as a starting point for physicians to make modifications, based on their clinical judgment.

Expression of vascular endothelial growth factor (VEGF) and VEGF-receptor messenger ribonucleic acids in the peri-implantation rabbit uterus

The endometrial vasculature undergoes expansion during preimplantation stages and, even more prominently, after implantation. In addition to angiogenesis, vascular hyperpermeability accompanies the attachment and invasion of blastocysts into the uterine lining. Vascular endothelial growth factor (VEGF) is an angiogenic factor expressed in mammalian uteri that also has potent activity in inducing vascular permeability. Rabbit uteri were examined using Northern and in situ hybridization to assess the temporal and spatial expression of VEGF and its receptor (Flk-1, Flt-1) mRNAs during the pre- and peri-implantation periods (Days 0-8). Steady-state levels of VEGF mRNA were highest in endometrium at estrous and peri-implantation stages (Days 6-8). In situ hybridization revealed a shift from uniform expression of VEGF transcripts throughout the uterus at estrus and Day 4, to an endometrial epithelial localization just before and during implantation. At implantation sites, a pronounced signal was present in the trophoblastic knobs, the syncytial aggregates that attach to and invade the endometrium. VEGF protein was detected by immunoblot analysis in peri-implantation-stage uteri but was below the limit of detection in estrous endometrium. VEGF receptor mRNAs were expressed in the uterus at all stages examined, with high levels of Flk-1 and Flt-1 at estrus and again just before implantation, 6-3/4 days pregnant. The high level just before implantation correlates with in situ hybridization results showing a prominent, but transient, signal for Flk-1 mRNA in the endometrial epithelium. During implantation, Flk-1 mRNA was associated with blood vessels of the endometrial stroma. We conclude that VEGF is a candidate factor for the induction of vascular hyperpermeability at implantation in the rabbit and in the angiogenic process that follows.

Inappropriate expression of human transforming growth factor (TGF)-alpha in the uterus of transgenic mouse causes downregulation of TGF-beta receptors and delays the blastocyst-attachment reaction

In the mouse, the initiation of the attachment reaction between the blastocyst trophectoderm and luminal epithelium of the receptive uterus occurs in the evening (2200-2300 h) of day 4 of pregnancy (day 1 = vaginal plug) and is followed by proliferation and differentiation of stromal cells into decidual cells at the sites of blastocyst attachment. This investigation demonstrates that an inappropriate expression of the human transforming growth factor alpha (hTGF-alpha) transgene in the uterus under the direction of a mouse metallothionein-I promoter downregulates uterine expression of TGF-beta receptor subtypes and delays the initiation of implantation (attachment reaction) resulting in delayed parturition. This delay in the attachment reaction is accompanied by deferred uterine expression of amphiregulin. The results suggest that a coordinated 'cross-talk' between the signaling pathways executed by epidermal growth factor-like growth factors and TGF-beta 5 is important for the normal implantation process.

Laser-doppler evaluation of the human tympanic membrane by measuring blood flow, volume, and velocity

From a hospital setting, a sample base of 50 people with normal hearing, was used to study the otoacoustic phenomenon of the ear. Human volunteers were taken into an acoustic room and allowed to rest for 5 minutes. Each volunteer inserted a probe as close to the tympanic membrane as possible. The objective of the study was to determine the pattern of distribution of blood flow, volume, and velocity of erythrocytes circulating in blood vessels of the tympanic membrane. This was achieved by recording numerical values for the flow, volume, and velocity of erythrocytes using the laser-Doppler flowmeter. Analysis of the results showed two distinct relationships, a negative exponential curve in the blood flow for the right and left ear, and a Gaussian distribution for the velocity and volume of erythrocytes for both ears.

Differential expression of the erbB2 gene in the periimplantation mouse uterus: potential mediator of signaling by epidermal growth factor-like growth factors

Ligand-receptor signaling with the epidermal growth factor (EGF) family of growth factors in the uterus and embryo is considered to be important for implantation. The EGF family includes EGF, transforming growth factor-alpha, heparin binding-EGF, amphiregulin, beta-cellulin, epiregulin, and heregulins, whereas the receptor family (the erbB genes) consists of erbB1 (EGF-receptor, EGF-R), erbB2, erbB3, and erbB4. Interactions of uterine EGF-R with EGF-like ligands have been examined, but limited information is available regarding the status of other receptor subtypes. Thus, we examined the expression of the erbB2 gene in the mouse uterus during the periimplantation period (days 1-8 of pregnancy) and after 17 beta-estradiol and/or progesterone stimulation. Northern blot hybridization detected two transcripts (approximately 4.0 and 5.0 kb) of erbB2 messenger RNA (mRNA) in day 1-8 uterine polyadenylated RNA samples. In situ hybridization experiments showed unique uterine cell-specific erbB2 mRNA distribution. On days 1-4, unlike the full-length erbB1 mRNA which is not expressed in the uterine epithelium, the erbB2 mRNA was detected primarily in epithelial cells; the day 1 uterus showed the highest accumulation. On day 5, the epithelium and the decidualizing stromal cells around the implanting blastocyst exhibited accumulation of this mRNA. On days 6-8, the accumulation persisted in the epithelium at both the implantation and interimplantation sites in addition to modest levels of signals in the secondary decidual zone. On days 7 and 8, accumulation of the erbB2 mRNA was also prominent in the trophoblastic giant cells. Western blotting detected a predicted protein of 185 kDa in day 4 uterine membrane preparations. Results of immunocytochemistry demonstrated colocalization of the erbB2 protein with its mRNA in the periimplantation uterus. The uterine ErbB2 underwent phosphorylation by several members of the EGF family. Treatment of adult ovariectomized mice with 17 beta-estradiol, but not progesterone, up-regulated the expression of the erbB2 mRNA by more than 3.5-fold, as determined by quantitative reverse transcription-PCR, and this increase was limited to the epithelium, as revealed by in situ hybridization. Collectively, the results place ErbB2 as a potential candidate receptor subtype for interaction with the EGF-related ligands in epithelial cell proliferation/differentiation during the preimplantation period and stromal cell proliferation/decidualization during the postimplantation period.

Potential sites of prostaglandin actions in the periimplantation mouse uterus: differential expression and regulation of prostaglandin receptor genes

Prostaglandins (PGs), especially PGE2 and PGF2alpha, are considered important for blastocyst spacing, implantation, and decidualization in the rodent uterus. However, information regarding uterine sites of PG actions in these processes is lacking. PGE2 or PGF2alpha interacts with specific G protein-coupled membrane receptors. PGE2 receptors are classified into four subtypes, EP1, EP2, EP3, and EP4. While EP1 is coupled to Ca2+ mobilization, activation of EP2 and EP4 triggers stimulation of adenylyl cyclase. In contrast, activation of EP3 inhibits adenylyl cyclase. PGF2alpha receptor (FP) is coupled to stimulation of phospholipase C-inositol trisphosphate (IP3) pathway and Ca2+ mobilization. This investigation demonstrates that PGE2 and PGF2alpha receptor genes are expressed in a temporal and cell-specific manner in the periimplantation mouse uterus. In the mouse, the attachment reaction occurs in the evening (2200-2300 h) of Day 4 of pregnancy and is preceded by embryo spacing, uterine edema, and luminal closure resulting in an intimate apposition of the blastocyst with the uterine luminal epithelium. Expression of EP3 and FP primarily in the circular muscle of the myometrium on Days 3-5 of pregnancy suggests that the circular muscle, not the longitudinal muscle, is the primary target for PG-mediated uterine contractions required for embryo transport, spacing, and/or accommodation in the uterus. In contrast, expression of EP3 in a subpopulation of cells in the stromal bed at the mesometrial side, and of EP4 in the epithelium and stroma on these days, suggests that PGE2 effects on uterine preparation for implantation (such as epithelial cell differentiation, stromal cell proliferation, uterine edema, luminal closure, and increased localized endometrial vascular permeability at the sites of blastocyst attachment) are mediated by these receptor subtypes. Similar expression patterns of EP3 and EP4 in the Day 4 pseudopregnant mouse uterus or in the ovariectomized uterus under combined treatment with estrogen and progesterone suggest that these genes are regulated by ovarian steroids rather than by the embryo during the preimplantation period (Days 1-4). In contrast, the expression of these genes during the postimplantation period (Days 5-8) is associated with the onset of decidualization.

Retinoic acid-induced alteration of cell surface topography and other changes in an oral carcinoma cell line in culture

Nature of antiproliferative action of retinoic acid (RA) on KB cells was studied by using monolayer and agar culture techniques. RA-treated cultures showed increased requirement of serum for their growth. Growth of colonies in agar culture was significantly retarded when cells were treated with 40 mumol RA. RA-induced growth inhibitions in both monolayer and agar cultures were independent of cell seeding densities. Cortisone and hydrocortisone showed no reversal of the inhibitory effects induced by RA on KB cells. Scanning electron microscopy study revealed a significant alteration in cell surface topography of RA-treated cells in monolayer culture. The results demonstrate that RA has a potential of reversing some of the properties which are associated with transformed state of oral carcinoma cells.

Ontogeny of GABA pathway in human fetal brains

The developmental profiles of gamma-aminobutyric acid (GABA), its biosynthesizing enzyme L-glutamic acid decarboxylase (GAD) and its degradating enzymes gamma-aminobutyric acid-alpha-ketoglutaric acid transaminase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH) in four different regions of human fetal brains have been evaluated. The GABA pathway was found to be maximally active in fetal brains during the third trimester of pregnancy. The relative activities of the enzymes as well as GABA content were least in pons compared to cerebrum, cerebellum and mid brain regions throughout the period of fetal development.

Inhibition patterns of a model complex mimicking the reductive half-reaction of sulphite oxidase

Different inhibition types of the saturation kinetics involving a synthesized model complex, [Bu4N]3[MoVIO2(mnt)2] (E) (where mnt2- = 1,2-dicyanoethylenedithiolate), and HSO3- as the substrate (S) by structurally similar anions SO4(2-), H2PO4- and H2PO3- have been shown for the first time in relevance to the reductive half reaction of the native enzyme sulphite oxidase. SO4(2-) acts as a competitive inhibitor. The mixed-type non-competitive inhibition by H2PO4- and the sigmoidal-type inhibition by H2PO3- are explained by a diamond-configuration random-order model. This involves a random binding sequence of the substrate and the inhibitor, and forms, in addition to two binary complexes [enzyme-substrate (ES) and enzyme-inhibitor (EI)], one enzyme-substrate-inhibitor-type ternary complex (ESI) by participation of at least one more binding site in addition to the catalytic site. This is possible in the present case only by co-ordination enhancement of molybdenum in E. This co-ordination expansion is brought about by nucleophilic attack of the substrate or the inhibitor at the molybdenum, forming a hepta-coordinated binary complex with the generation of an oxoanionic functional site, called the allosteric site. Analysis of the experimental data suggests that the inhibition by H2PO4- is due to the mechanism following either equilibrium conditions or a combination of steady-state and equilibrium conditions. With H2PO3-, the inhibition is due to the mechanism following the steady-state conditions. It is also shown that the ternary complex involving the enzyme, substrate and H2PO4- or H2PO3- is productive, but at a lower rate than that of the enzyme-substrate binary complex. Mixed-type inhibition with H2PO4- is actually of the type called "partially mixed competitive and non-competitive' as the inhibitor binds both to the catalytic site and to the allosteric site. The sigmoidal-type inhibition by H2PO3- is similar to heterotropic allosteric effect of mixed V,K type with the distinction, however, that the significance of co-operativity in this case is of kinetic importance only.

Oxidation of thiosulfate by a new bacterium, Bosea thiooxidans (strain BI-42) gen. nov., sp. nov.: analysis of phylogeny based on chemotaxonomy and 16S ribosomal DNA sequencing

A gram-negative bacterium which was capable of oxidizing reduced inorganic sulfur compounds was isolated from agricultural soil and designated BI-42. This new isolate grew on a wide range of organic substrates but was not able to grow autotrophically and lacked ribulose 1,5-bisphosphate carboxylase, a key enzyme of carbon dioxide fixation. These results suggested that strain BI-42 was a chemolithoheterotroph. Ammonia and nitrate were not used as sole nitrogen sources for growth, and strain BI-42 lacked glutamate synthase activity, which resulted in glutamate auxotrophy. The glutamate dehydrogenase activity of this organism was apparently insufficient for ammonia assimilation. On the basis of the results of additional biochemical tests, the G + C content of the DNA, the results of a respiratory ubiquinone analysis, the results of a 16S ribosomal DNA sequence analysis, the fatty acid composition, and the results of a membrane lipid analysis, strain BI-42 was identified as a phylogenetically and physiologically distinct taxon belonging to the alpha subclass of the Proteobacteria. Bosea thiooxidans gen. nov., sp. nov. is the name proposed for this taxon.

Incidence and significance of cardiac arrhythmia in geriatric oral surgery patients

We recorded heart rhythms of 40 older patients (20 medicated for cardiovascular disease and 20 not medicated for cardiovascular disease) during an outpatient oral surgery visit to determine overall arrhythmia incidence and severity, differences in incidence associated with cardiovascular medication status, and the impact of surgical intervention on arrhythmia incidence. We hypothesized that both groups would show similar arrhythmia numbers and types during surgical visits and that a history of medication for cardiovascular disease would not be an indicator of cardiac arrhythmia. Enrollment remained open until 20 patients older than 60 years of age from each group agreed to participate. Data were analyzed using the chi square statistic and Fisher's exact test (2-tailed). Included in the study were 24 women and 16 men; their mean age was 70.5 years (range, 60 to 86 years). Arrhythmias were detected in 17 patients and 33 of the 160 recorded rhythms. None of the detected arrhythmias were considered life-threatening. Significantly more arrhythmias occurred before administration of anesthesia than during administration of epinephrine-containing local anesthetics (p = 0.0001), and a greater number of rhythm disturbances were seen during the surgical procedure when compared with anesthesia administration (p = 0.0170). No differences in arrhythmia incidence were seen with increasing age, when male patients were compared with female patients, or when patients pharmacologically treated for cardiovascular disease were compared with patients not taking cardiovascular therapeutic medications. We conclude that although arrhythmias in this ambulatory population are common, they are typically benign in character and cardiovascular medication status is not indicative of their presence. In addition, minor oral surgery intervention with local anesthetics used in recommended dosages has no effect on cardiac arrhythmia status in the ambulatory geriatric population.

Transposon mutagenesis affecting thiosulfate oxidation in Bosea thiooxidans, a new chemolithoheterotrophic bacterium

Transposon insertion mutagenesis was used to isolate mutants of Bosea thiooxidans which are impaired in thiosulfate oxidation. Suicide plasmid pSUP5011 was used to introduce the transposon Tn5 into B. thiooxidans via Escherichia coli S17.1-mediated conjugation. Neomycin-resistant transconjugants occurred at a frequency of 2.2 X 10(-4) per donor. Transconjugants defective in thiosulfate oxidation were categorized into three classes on the basis of growth response, enzyme activities, and cytochrome patterns. Class I mutants were deficient in cytochrome c, and no thiosulfate oxidase activity was detected. Class II mutants retained the activities of key enzymes of thiosulfate metabolism, although at reduced levels. Mutants of this class grown on mixed-substrate agar plates deposited elemental sulfur on the colony surfaces. Class III mutants were unable to utilize thiosulfate, though they had normal levels of cytochrome c. The transposon insertions occurred at different chromosomal positions, as confirmed by Southern blotting of chromosomal DNA of mutants deficient in thiosulfate oxidation, a deficiency which resulted from single insertions of Tn5.