Contribution of arbuscular mycorrhizal fungi and/or bacteria to enhancing plant drought tolerance under natural soil conditions: effectiveness of autochthonous or allochthonous strains

Autochthonous microorganisms [a consortium of arbuscular-mycorrhizal (AM) fungi and Bacillus thuringiensis (Bt)] were assayed and compared to Rhizophagus intraradices (Ri), Bacillus megaterium (Bm) or Pseudomonas putida (Psp) and non-inoculation on Trifolium repens in a natural arid soil under drought conditions. The autochthonous bacteria Bt and the allochthonous bacteria Psp increased nutrients and the relative water content and decreased stomatal conductance, electrolyte leakage, proline and APX activity, indicating their abilities to alleviate the drought stress. Mycorrhizal inoculation significantly enhanced plant growth, nutrient uptake and the relative water content, particularly when associated with specific bacteria minimizing drought stress-imposed effects. Specific combinations of autochthonous or allochthonous inoculants also contributed to plant drought tolerance by changing proline and antioxidative activities. However, non-inoculated plants had low relative water and nutrients contents, shoot proline accumulation and glutathione reductase activity, but the highest superoxide dismutase activity, stomatal conductance and electrolyte leakage. Microbial activities irrespective of the microbial origin seem to be coordinately functioning in the plant as an adaptive response to modulated water stress tolerance and minimizing the stress damage. The autochthonous AM fungi with Bt or Psp and those allochthonous Ri with Bm or Psp inoculants increased water stress alleviation. The autochthonous Bt showed the greatest ability to survive under high osmotic stress compared to the allochthonous strains, but when single inoculated or associated with Ri or AM fungi were similarly efficient in terms of physiological and nutritional status and in increasing plant drought tolerance, attenuating and compensating for the detrimental effect of water limitation.

Management of Larynx and Trachea Donors

INTRODUCTION

Laryngeal transplantation is a possibility for patients with irreversible laryngeal disease, such as complex trauma and larynx cancer. The objective of performing this procedure was to solve problems that these patients face with a laryngectomy. The medical literature has reviews about larynx transplantations, but almost nothing about the larynx donor. The following is our experience on management of these donors.

MATERIALS AND METHODS

Selection criteria was as follows: (1) 18-50 years old; (2) gender and ABO blood type matched between donor and recipient; (3) No abuse of tobacco, cocaine, and marijuana, (4) tracheal intubation time <3 days; and (5) time in the intensive care unit <7 days. The preservation was simple hypothermia with larynx infusion via the carotid artery with University of Wisconsin solution.

RESULTS

Between 2001 and 2006, we managed 25 donors, among whom 12 grafts were discarded. The 13 larynx donors were of average age 27.2 +- 7.9 years and their cause of death was head trauma. Each was of male and 12 were multiorgan donors. Three donors had previous consumption of tobacco and 2 donors of marijuana. There were 2 cases of acute rejection episodes. Graft survival rate at 2 years was 90%.

DISCUSSION

These donors may have differences from other multiorgan donors: (1) they do not require strict fluid management; (2) vasoactive agents may be used in higher doses than in organ donors, and (3) the larynx tolerates hemodynamic instability. It was necessary to use some donors who had used addictive substances, showing that some selection criteria may be flexible. There was no conflict between thoracic surgeons and larynx surgeons. The priority always was for life-saving organs. Family consent was sometimes difficult because of the retrieval times and body donor reconstruction. The larynx surgery retrieval demanded an additional 2-5 hours during routine multiorgan donor surgery, and always the family asked about body reconstruction. The body appearance was always preserved.

Histologic Assessment of Donor Kidneys and Graft Outcome: Multivariate Analyses

We performed a multivariate analysis to evaluate the importance of histologic parameters in donor kidney biopsies as predictors of graft outcome.

METHODS

Wedge protocol biopsies from a single center were analyzed for glomerulosclerosis (GS), interstitial fibrosis (IF), tubular atrophy (TA), arteriosclerosis (AS), and arteriolar hyalinosis (AH). Alterations were quantified as percentage (GS, IF) or semiquantified according to Banff criteria (IF, TA, AS, AH). We calculated creatinine clearance (CrCl) at 1, 2, and 3 years posttransplant. Donor data included age, gender, and type: non-heart-beating donor or brain dead donors. Recipient data included age, gender, cold ischemia time, number of HLA mismatches, peak level of the panel reactive antibody (PRA), number of acute rejection episodes (ARE), and presence or absence of cytomegalovirus (CMV) disease. Univariate and multivariate analyses were performed. Follow-up range was 1 to 4.2 years.

RESULTS

GS, IF, TA, and AH were associated with graft survival in the multivariate analysis. The histologic parameters were associated with CrCl at several posttransplant time intervals, but the significance of association was lost in the multivariate analysis. Donor age showed a better correlation with graft function. In the univariate analyses adjusting for donor age, only IF and AH were associated with graft function.

CONCLUSIONS

Histologic parameters showed a modest association with graft function. In our study, donor age is the better predictor of graft function. IF and AH may be similar to or better than GS as predictors of graft outcome.

Organ Donation in Latin America

Recently in Latin America, there has been a strong influence of the "Spanish model" of organ procurement. In 2001, The "Punta Cana Group" was created by Latin American transplantation coordinators with the objective of registering and improving the system of donation and procurement. In many countries there is no universal financial support from the government for medical treatment, including dialysis and transplantation. In other countries there is complete financial support for all of the population, including immunosuppressive drugs. Practically all countries have transplantation laws that follow ethical concepts, such as brain death diagnosis criteria, forms of consent, criteria of allocation, and inhibition of commerce. The rate of potential donors notified in countries that perform transplantations with deceased donors varied from 6 to 47 per million population yearly (pmp/y); The rate of effective donors varied from 1 to 20 pmp. In 2004, the mean rate of effective donors in Latin America was 5.4 pmp. The family refusal rate for the donation of organs varied from 28% in Uruguay to 70% in Peru. In some countries, such as Puerto Rico, Uruguay, and Cuba, it was more than 15 pmp, whereas in others countries deceased donors were practically not used. The number of patients on the waiting list for solid organ transplants in 12 Latin American countries is 55,000. Although the donation rate has increased by 100% during the last 10 years, it is lower than that in Europe (15 pmm/y) or the United States (20 pmp/y).

The Perfusion Pressure in Non–Heart-Beating Donors May Expand the Glomeruli

INTRODUCTION

We have observed expanded glomeruli in biopsies of kidneys from non-heart-beating donors (NHBDs). We sought to determine the differences in glomerular size between NHBDs and brain-dead donors and to assess whether glomerular size impacted graft outcome.

METHODS

We estimated the glomerular area using the maximal planar area (MPA) method in 198 pretransplant biopsies from 119 donors: 54 (45.4%) NHBDs and 65 (54.6%) brain-dead donors. Donor data and graft outcomes were correlated with MPA and percentage of glomerulosclerosis. The range of follow-up was 1 to 3 years. Uni- and multivariate analyses were performed.

RESULTS

MPA was larger among NHBDs. MPA and GS both significantly correlated with donor age. The association between MPA and age was independent of nephron loss (ie; GS). Increased glomerular size was only observed among donors younger than 50 years. Graft survival and function were not independently associated with MPA. Donor age was a better predictor of graft outcome.

CONCLUSIONS

The perfusion pressure used in NHBDs may expand the glomeruli, but this maneuver does not have any effect on graft outcome. Among donors without severe changes, glomerular size increment shows a limit around the sixth decade of life. In our study, MPA was not an independent predictor of graft survival or function.

Detection of Amastigotes of Trypanosoma Cruzi in a Kidney Graft With Acute Dysfunction

We described a case of allograft kidney dysfunction associated with renal parenchymal infection with amastigotes of Trypanosoma cruzi. The patient was diagnosed as being chronically infected prior to transplantation. The infection was probably acquired by blood transfusion. He could not complete antiparasitic treatment due to drug toxicity. He was transplanted from a cadaver who showed a negative test for Chagas' disease. One year after transplantation the serum creatinine progressively increased. Histological examination of renal biopsy revealed intracytoplasmic amastigotes of T cruzi. No evidence of other specific alterations in the graft was detected. It was unknown whether graft dysfunction was only due to parasitic infection. The present case confirmed that T cruzi can infect kidney grafts and that immunosuppression in kidney transplantation is potentially a cause of dissemination of Chagas' disease.

Liver transplantation in Medellin, Colombia: Initial experience

OBJECTIVE

The goal of this article is to present the experience of a new liver transplant team.

MATERIALS AND METHODS

This review includes all patients who received a liver transplant between March 15, 2000 and March 15, 2003.

RESULTS

We performed 87 transplantations on 84 patients; 39 were females and 45 were males of average age 43.6 years, including 6 children. The majority of the patients were from Colombia with time on the waiting list of less than 1 month. The average donor age was 26.7 years. The preservation solutions included Wisconsin, HTK-Brettschneider (Custodiol), and Corpaúl (similar to Henn-Ross). In this study, 95.4% were whole livers, with 97.7% using the piggyback method. We placed 23 arterial grafts and 2 venous grafts for vascular reconstructions; 95.4% were duct-to-duct anastomosis (95.4%). Among the cohort, 8.3% experienced acute rejection and 1.2% experienced chronic rejection. Two patients required retransplantation due to hepatic artery thrombosis with biliary tree necrosis.

CONCLUSIONS

We consider that we have passed the crisis of beginning a new program with a reduction in postoperative complications and improving patient and graft survival. At present, we are a center that performs liver transplantations in adults and children, with a good organ donation culture in our city that allows us to offer a waiting time on the list less than one month. Neither a veno-venous bypass nor a T-tube were necessary for our cases. We also have developed a new, less expensive form of perfusing the liver in the donor.

Organs transplanted from intoxicated donors

PURPOSE

The purpose of our study was to evaluate short- and long-term results of transplants from cadaver donors who have died of poisoning by various substances.

MATERIALS AND METHODS

The actuarial survival rate of organs from intoxicated donors was calculated using the Kaplan-Meier method.

RESULTS

Among the 507 donors between January 1998 and December 2002, 5 (0.98%) had a cause of brain death of poisoning, namely, organo-phosphates (n = 2), methanol (n = 1), cyanide (n = 1) and acetylsalicilic acid(n = 1), from whom were procured 10 kidneys, 1 liver, 2 corneas, and 1 set of bones. The follow up for patients receiving solid organs was 15.2 months (range, 0-48 months). At 3 months, 90% of kidneys had normal function. No delayed graft function rejection episodes or major complications were reported in any recipient. None showed evidence of acute or chronic poisoning. Two died, 1 early mortality was due to anesthetic complications and the other at 17 months to an unknown cause. Actuarial kidney survival rates were 90% and 80% at 12 and 24 months, respectively. The liver recipient was well at the end of follow up.

CONCLUSION

Using organs of poisoned donors is feasible with comparable graft survival rates to other recipient.

A WbpL mutant of Pseudomonas putida DOT-T1E strain, which lacks the O-antigenic side chain of lipopolysaccharides, is tolerant to organic solvent shocks

Lipopolysaccharides (LPS) are major components of the outer membrane of gram-negative bacteria and are considered a defense barrier. To determine if LPS play a role in resistance to solvents in the solvent-tolerant Pseudomonas putida DOT-T1E strain, we have generated mutants unable to synthesize the O-antigen side chain of LPS. The wbpL gene, encoding the enzyme that begins the synthesis of the O-antigen side chain of LPS of the solvent-tolerant strain, was cloned, sequenced, and knocked out in vitro with a cassette encoding kanamycin resistance, and a mutant called WbpL0 of the DOT-T1E strain was generated in vivo by site-directed mutagenesis. The WbpL mutant was compared with the wild-type strain with regard to tolerance to a number of toxic compounds, including chelating agents, organic acids, detergents, and aromatic hydrocarbons. It was found that the mutant was as tolerant as the wild-type strain to organic acids and aromatic hydrocarbons and more sensitive to ethylenediaminetetraacetic acid and deoxycholate.

Three efflux pumps are required to provide efficient tolerance to toluene in Pseudomonas putida DOT-T1E

In Pseudomonas putida DOT-T1E multidrug efflux pumps of the resistance-nodulation-division family make a major contribution to solvent resistance. Two pumps have been identified: TtgABC, expressed constitutively, and TtgDEF, induced by aromatic hydrocarbons. A double mutant lacking both efflux pumps was able to survive a sudden toluene shock if and only if preinduced with small amounts of toluene supplied via the gas phase. In this article we report the identification and characterization in this strain of a third efflux pump, named TtgGHI. The ttgGHI genes form an operon that is expressed constitutively at high levels from a single promoter. In the presence of toluene the operon is expressed at an even higher level from two promoters, the constitutive one and a previously unreported one that is inducible and that partially overlaps the constitutive promoter. By site-directed mutagenesis we constructed a single ttgH mutant which was shown to be unable to survive sudden 0.3% (vol/vol) toluene shocks regardless of the preculture conditions. The mutation was transferred to single and double mutants to construct mutant strains in which two or all three pumps are knocked out. Survival analysis of induced and noninduced cells revealed that the TtgABC and TtgGHI pumps extruded toluene, styrene, m-xylene, ethylbenzene, and propylbenzene, whereas the TtgDEF pump removed only toluene and styrene. The triple mutant was hypersensitive to toluene, as shown by its inability to grow with toluene supplied via the vapor phase.

Mutations in genes involved in the flagellar export apparatus of the solvent-tolerant Pseudomonas putida DOT-T1E strain impair motility and lead to hypersensitivity to toluene shocks

Pseudomonas putida DOT-T1E is a solvent-tolerant strain able to grow in the presence of 1% (vol/vol) toluene in the culture medium. Random mutagenesis with mini-Tn5-'phoA-Km allowed us to isolate a mutant strain (DOT-T1E-42) that formed blue colonies on Luria-Bertani medium supplemented with 5-bromo-4-chloro-3-indolylphosphate and that, in contrast to the wild-type strain, was unable to tolerate toluene shocks (0.3%, vol/vol). The mutant strain exhibited patterns of tolerance or sensitivity to a number of antibiotics, detergents, and chelating agents similar to those of the wild-type strain. The mutation in this strain therefore seemed to specifically affect toluene tolerance. Cloning and sequencing of the mutation revealed that the mini-Tn5-'phoA-Km was inserted within the fliP gene, which is part of the fliLMNOPQRflhBA cluster, a set of genes that encode flagellar structure components. FliP is involved in the export of flagellar proteins, and in fact, the P. putida fliP mutant was nonmotile. The finding that, after replacing the mutant allele with the wild-type one, the strain recovered the wild-type pattern of toluene tolerance and motility unequivocally assigned FliP a function in solvent resistance. An flhB knockout mutant, another gene component of the flagellar export apparatus, was also nonmotile and hypersensitive to toluene. In contrast, a nonpolar mutation at the fliL gene, which encodes a cytoplasmic membrane protein associated with the flagellar basal body, yielded a nonmotile yet toluene-resistant strain. The results are discussed regarding a possible role of the flagellar export apparatus in the transport of one or more proteins necessary for toluene tolerance in P. putida DOT-T1E to the periplasm.

Global and cognate regulators control the expression of the organic solvent efflux pumps TtgABC and TtgDEF of Pseudomonas putida

Pseudomonas putida DOT-T1E grows on a water-toluene double liquid phase. Toluene tolerance in this microorganism is mainly achieved by at least two efflux pumps that belong to the RND family. The TtgDEF efflux pump is induced by toluene, whereas the other efflux pump, called TtgABC, is expressed at a high level in cells not exposed to toluene and at a lower level in cells grown with toluene. The ttgR gene is adjacent to the ttgABC operon and is transcribed divergently from ttgA. The expression level of ttgR was fourfold higher in cells growing in the presence of toluene than in its absence. In a TtgR-deficient background, expression from the ttgA promoter increased about 20-fold, suggesting that TtgR represses expression from the ttgA promoter. In this mutant, background expression of the ttgR gene was also much higher than in the wild-type background; however, its level of expression increased in the presence of toluene. In a ttgR mutant background, expression from the ttgD promoter followed the same pattern of expression as in the wild type. Analysis of a P. putida pTn5cat mutant that exhibited increased sensitivity to a sudden toluene shock, regardless of whether or not it was previously exposed to low toluene concentrations, revealed that pTn5cat had interrupted an lrp-like gene. The ttgR gene was expressed at very high levels in this mutant, with concomitant repression of expression of the ttgABC operon. The second ttgDEF efflux pump was expressed at low levels in this mutant strain, suggesting that the Lrp-like protein is a global regulatory protein involved in the solvent-tolerant response of this strain.

Efflux pumps involved in toluene tolerance in Pseudomonas putida DOT-T1E

The basic mechanisms underlying solvent tolerance in Pseudomonas putida DOT-T1E are efflux pumps that remove the solvent from bacterial cell membranes. The solvent-tolerant P. putida DOT-T1E grows in the presence of high concentrations (e.g., 1% [vol/vol]) of toluene and octanol. Growth of P. putida DOT-T1E cells in LB in the presence of toluene supplied via the gas phase has a clear effect on cell survival: the sudden addition of 0.3% (vol/vol) toluene to P. putida DOT-T1E pregrown with toluene in the gas phase resulted in survival of almost 100% of the initial cell number, whereas only 0.01% of cells pregrown in the absence of toluene tolerated exposure to this aromatic hydrocarbon. One class of toluene-sensitive octanol-tolerant mutant was isolated after Tn5-'phoA mutagenesis of wild-type P. putida DOT-T1E cells. The mutant, called P. putida DOT-T1E-18, was extremely sensitive to 0.3% (vol/vol) toluene added when cells were pregrown in the absence of toluene, whereas pregrowth on toluene supplied via the gas phase resulted in survival of about 0.0001% of the initial number. Solvent exclusion was tested with 1,2,4-[14C]trichlorobenzene. The levels of radiochemical accumulated in wild-type cells grown in the absence and in the presence of toluene were not significantly different. In contrast, the mutant was unable to remove 1,2,4-[14C]trichlorobenzene from the cell membranes when grown on Luria-Bertani (LB) medium but was able to remove the aromatic compound when pregrown on LB medium with toluene supplied via the gas phase. The amount of 14C-labeled substrate in whole cells increased in competition assays in which toluene-and xylenes were the unlabeled competitors, whereas this was not the case when benzene was the competitor. This finding suggests that the exclusion system works specifically with certain aromatic substrates. The mutation in P. putida DOT-T1E-18 was cloned, and the knockedout gene was sequenced and found to be homologous to the drug exclusion gene mexB, which belongs to the efflux pump family of the resistant nodulator division type.

Survival in soil of different toluene-degrading Pseudomonas strains after solvent shock

We assayed the tolerance to solvents of three toluene-degrading Pseudomonas putida strains and Pseudomonas mendocina KR1 in liquid and soil systems. P. putida DOT-T1 tolerated concentrations of heptane, propylbenzene, octanol, and toluene of at least 10% (vol/vol), while P. putida F1 and EEZ15 grew well in the presence of 1% (vol/vol) propylbenzene or 10% (vol/vol) heptane, but not in the presence of similar concentrations of octanol or toluene. P. mendocina KR1 grew only in the presence of heptane. All three P. putida strains were able to become established in a fluvisol soil from the Granada, Spain, area, whereas P. mendocina KR1 did not survive in this soil. The tolerance to organic solvents of all three P. putida strains was therefore assayed in soil. The addition to soil of 10% (vol/wt) heptane or 10% (vol/wt) propylbenzene did not affect the survival of the three P. putida strains. However, the addition of 10% (vol/wt) toluene led to an immediate decrease of several log units in the number of CFU per gram of soil for all of the strains, although P. putida F1 and DOT-T1 subsequently recovered. This recovery was influenced by the humidity of the soil and the incubation temperature. P. putida DOT-T1 recovered from the shock faster than P. putida F1; this allowed the former strain to become established at higher densities in polluted sites into which both strains had been introduced.

Removal of high concentrations of nitrate from industrial wastewaters by bacteria

Klebsiella oxytoca isolate 15 was isolated from the grounds of a nitration factory and was found to be tolerant to nitrate at concentrations up to 0.5 to 1 M. Physicochemical parameters for optimal growth conditions for K. oxytoca isolate 15 were established. Growth took place when the nitrate concentration in the medium was less than 150 mM, and full nitrate consumption required about 14 g of C per g of N. This strain was able to remove nitrate without accumulating nitrite. The system was scaled up to a 40-liter pilot plant and was operated on-site satisfactorily.

Mechanisms for solvent tolerance in bacteria

The development of tolerance in Pseudomonas putida DOT-T1 to toluene and related highly toxic compounds involves short- and long-term responses. The short-term response is based on an increase in the rigidity of the cell membrane by rapid transformation of the fatty acid cis-9,10-methylene hexadecanoic acid (C17:cyclopropane) to unsaturated 9-cis-hexadecenoic acid (C16:1,9 cis) and subsequent transformation to the trans isomer. The long-term response involves in addition to the changes in fatty acids, alterations in the level of the phospholipid polar head groups: cardiolipin increases and phosphatidylethanolamine decreases. The two alterations lead to increased cell membrane rigidity and should be regarded as physical mechanisms that prevent solvent penetrance. Biochemical mechanisms that decrease the concentration of toluene in the cell membrane also take place and involve: (i) a solvent exclusion system and (ii) metabolic removal of toluene via oxidation. Mutants unable to carry out cis --> trans isomerization of unsaturated lipids, that exhibit altered cell envelopes because of the lack of the OprL protein, or that are unable to exclude toluene from cell membranes are hypersensitive to toluene.

Metabolism of nitrate esters by a consortium of two bacteria

The products of condensation of organic alcohols and nitric acid are nitrate esters with the general structure C-O-NO2. These products are widely employed as vasodilators and explosives, and are true xenobiotic compounds, as they do not occur in nature. We have isolated and characterized a consortium of two microorganisms, Arthrobacter ilicis and Agrobacterium radiobacter, that mineralized recalcitrant ethylene glycol dinitrate. The Arthrobacter strain was the actual degrading microorganism, although the second microbe facilitated mineralization. The biodegradation of ethylene glycol dinitrate by A. ilicis involved the progressive elimination of the nitro groups from the organic molecule to generate ethylene glycol, which was then mineralized. Waters polluted with ethylene glycol dinitrate have been shown amenable to biological treatment in a pilot plant with wastewaters generated during the synthesis of the chemical in a factory.

Isolation and expansion of the catabolic potential of a Pseudomonas putida strain able to grow in the presence of high concentrations of aromatic hydrocarbons

Pseudomonas putida DOT-T1 was isolated after enrichment on minimal medium with 1% (vol/vol) toluene as the sole C source. The strain was able to grow in the presence of 90% (vol/vol) toluene and was tolerant to organic solvents whose log P(ow) (octanol/water partition coefficient) was higher than 2.3. Solvent tolerance was inducible, as bacteria grown in the absence of toluene required an adaptation period before growth restarted. Mg2+ ions in the culture medium improved solvent tolerance. Electron micrographs showed that cells growing on high concentrations of toluene exhibited a wider periplasmic space than cells growing in the absence of toluene and preserved the outer membrane integrity. Polarographic studies and the accumulation of pathway intermediates showed that the strain used the toluene-4-monooxygenase pathway to catabolyze toluene. Although the strain also thrived in high concentrations of m- and p-xylene, these hydrocarbons could not be used as the sole C source for growth. The catabolic potential of the isolate was expanded to include m- and p-xylene and related hydrocarbons by transfer of the TOL plasmid pWW0-Km.

Mineralization of p-methyl-14C-benzoate in soils by Pseudomonas putida (pWW0)

Pseudomonas putida bearing the archetypal TOL plasmid pWW0 metabolizes p-methylbenzoate through a meta-cleavage pathway. In complex environments such as soils that are relatively rich in organic matter, we observed metabolism of p-methyl-14C-benzoate, which could be monitored as 14CO2 evolution from the labelled alkylaromatic. Linear 14CO2 evolution in soils took place for at least a month, although efficient mineralization of the alkylaromatic required appropriate mass transfer to allow the bacterial cell and target chemical to remain in close contact.

Construction of a Pseudomonas hybrid strain that mineralizes 2,4,6-trinitrotoluene

A bacterium, Pseudomonas sp. strain C1S1, able to grow on 2,4,6-trinitrotoluene (TNT), 2,4- and 2,6-dinitrotoluene, and 2-nitrotoluene as N sources, was isolated. The bacterium grew at 30 degrees C with fructose as a C source and accumulated nitrite. Through batch culture enrichment, we isolated a derivative strain, called Pseudomonas sp. clone A, which grew faster on TNT and did not accumulate nitrite in the culture medium. Use of TNT by these two strains as an N source involved the successive removal of nitro groups to yield 2,4- and 2,6-dinitrotoluene, 2-nitrotoluene, and toluene. Transfer of the Pseudomonas putida TOL plasmid pWW0-Km to Pseudomonas sp. clone A allowed the transconjugant bacteria to grow on TNT as the sole C and N source. All bacteria in this study, in addition to removing nitro groups from TNT, reduced nitro groups on the aromatic ring via hydroxylamine to amino derivatives. Azoxy dimers probably resulting from the condensation of partially reduced TNT derivatives were also found.

Conjugational transfer of recombinant DNA in cultures and in soils: host range of Pseudomonas putida TOL plasmids

Recombinant TOL plasmid pWWO-EB62 allows Pseudomonas putida to grow on p-ethylbenzoate. This plasmid can be transferred to other microorganisms, and its catabolic functions for the metabolism of alkylbenzoates are expressed in a limited number of gram-negative bacteria, including members of pseudomonad rRNA group I and Escherichia coli. Transfer of the recombinant plasmid to Erwinia chrysanthemi was observed, but transconjugants failed to grow on alkylbenzoates because they lost catabolic functions. Pseudomonads belonging to rRNA groups II, III, and IV, Acinetobacter calcoaceticus, and Alcaligenes sp. could not act as recipients for TOL, either because the plasmid was not transferred or because it was not stably maintained. The frequency of transfer of pWWO-EB62 from P. putida as a donor to pseudomonads belonging to rRNA group I was on the order of 1 to 10(-2) transconjugant per recipient, while the frequency of intergeneric transfer ranged from 10(-3) to 10(-7) transconjugant per recipient. The profile of potential hosts was conserved when the donor bacterium was Escherichia coli or Erwinia chrysanthemi instead of P. putida. No intergeneric gene transfer of the recombinant TOL plasmid was observed in soils; however, intraspecies transfer did take place. Intraspecies transfer of TOL in soils was affected by the type of soil used, the initial inoculum size, and the presence of chemicals that could affect the survival of the donor or recipient bacteria.

Survival in soils of an herbicide-resistant Pseudomonas putida strain bearing a recombinant TOL plasmid

Pseudomonas putida EEZ15(pWW0-EB62) is a phosphinothricin (PPT)-resistant strain with a recombinant TOL plasmid which allows the strain to grow on p-ethylbenzoate. The survival of this strain in sterile agricultural soils depends on the physicochemical properties of the soil. The recombinant pWW0-EB62 plasmid and its catabolic functions were stable for periods of up to 1 month in bacteria introduced in unamended soils and only conferred selective advantage to the host bacteria without the plasmid or with the natural pWW0 plasmid when the soils were amended with low amounts of p-ethylbenzoate. The addition to soils of aromatics that are cometabolized by P. putida EEZ15(pWW0-EB62) had a detrimental effect on the survival of the bacteria, whereas low amounts of aromatics that are not metabolized by this bacterium had no effect on their survival. Survival of P. putida EEZ15(pWW0-EB62) was better at 4 and 25 degrees C than at 37 degrees C. The host bacterium carrying the recombinant pWW0-EB62 plasmid was established in unsterile soils.

Polyps in a low-risk colonic cancer population in Colombia, South America

Colonic polyps were systematically searched for in 508 specimens collected from unselected autopsies in individuals more than 10 years of age from Medellín, Colombia, a low-incidence geographic region for colorectal cancer. Adenomatous polyps have a low prevalence rate in both sexes, comparable to that found in Cali, Colombia and other populations with low risk for cancer. They were found more frequently in the right side of the colon and are rare in the sigmoid colon. They begin to appear in the third decade of life in both sexes. Prevalence rates for single and multiple polyps increase with age in both sexes, males showing higher rates than females at every age group. Adenomatous polyps in this population are usually less than 3 mm in diameter and do not show villous changes or epithelial atypia. Hyperplastic polyps were more frequently observed than adenomatous polyps and rates show a progressive increase with age in both sexes. Multiplicity also increases with age. Most polyps are located in the low rectum and sigmoid followed by the cecum and ascending colon. Usually hyperplastic polyps are smaller than 3 mm in diameter and do not show epithelial atypia. Juvenile polyps were infrequently found in this series because children less than 10 years old were excluded. Diverticular disease was also rare and, when found, was not associated with adenomatous polyps. The association between adenomatous polyps and colonic cancer is discussed based on findings in this report.

Premalignant lesions of the cervix in women of Cali, Colombia

A detailed histologic study was made of uterine cervices from 441 autopsy specimens from the population of Cali, Colombia. Women in this city have one of the highest registered incidence rates of cancer of the uterine cervix. The following prevalence (in percent) of lesions in adult women was found: cervicitis, 79; reserve cell hyperplasia, 14; squamous metaplasia, 41; dysplasia, 9. Contrary to expectations, no increase in prevalence of these lesions was found with age, lower socioeconomic status, or number of pregnancies. A similar study of a sample of hysterectomies performed for uterine prolapse showed approximately the same results. The findings suggest that promotional factors are more important than initiator factors in uterine cervical carcinogenesis.

Intestinal function and morphology in strongyloidiasis

Divergent available information on the capability of Strongyloides stercoralis to cause malabsorption prompted a long-term observation in which the nutritional state of the subjects was carefully defined. In spite of moderate to severe symptoms, well nourished patients, even with segmental jejunitis, did not show malabsorption. All patients presenting this parasitic infection with concomitant malnutrition showed absorptive defects. Abnormal absorption persisted in spite of parasitic cure when malnutrition was not immediately corrected, and disappeared with correction of the malnutrition even if parasitic infection was allowed to continue. The present experience indicates that the malabsorption syndrome seen in some cases of S. stercoralis infection is secondary to the concomitant malnutrition and not to the parasite per se.

Enterobacteriaceae in the jejunal microflora prevalence and relationship to biochemical and histological evaluations in healthy Colombian men

When 23 healthy native Southwestern Colombian men were studied to determine the prevalence of Enterobacteriaceae in the jejunal microflora in a sample of thoroughly evaluated tropical inhabitants who were normal by physical examination, chest x-ray, and medical history, 14 of the 23 proved to be Enterobacteriaceae-positive, with counts of 10(3) to 10(9) per milliliter of jejunal aspirate. Thirteen had Escherichia coli, and the fourteenth had Klebsiella pneumoniae. Four had a second species of Enterobacteriaceae associated with E. coli: three were K. pneumoniae, and one was Proteus morganii. Laboratory studies routinely done on all subjects disclosed a total of 18 low biochemical values, 17 of which were associated with 12 of the 14 Enterobacteriaceae-positive subjects: six were low in serum cholesterol, four low in serum vitamin B12, four low in D-xylose excretion, and three low in creatinine coefficient; whereas, the Enterobacteriaceae-negative subjects had normal values for all biochemical tests except for serum vitamin B12 in one case. Nitrogen balance means were significantly different for the two groups: 3.39 g for the Enterobacteriaceae-positive subjects and 1.94 g for the Enterobacteriaceae-negative. No relationship was evident when the histology of the jejunal biopsies was compared with the microbiological or laboratory findings. When the 23 subjects were grouped into those (N = 19) with significant microbial recoveries of any type and those (N = 4) without, the data yielded no meaningful relationships.

Gastric cancer in Colombia. III. Natural history of precursor lesions

The premalignant process in the gastric mucosa was studied by gastroscopic surveys of Colombian populations, and the prevalence of superficial gastritis, chronic atrophic gastritis, and intestinal metaplasia was calculated for population samples having a very high gastric cancer risk (Nariño), very low risk (Cartagena), and intermediate risk (Cali). The prevalence of individuals with normal mucosa in successive age groups was used to estimate "depletion" curves, which were taken as indicators of the dynamics of the premalignant process in each community. Differences corresponding to the geographic variation in stomach cancer risk were found: In the high-risk areas of Nariño, around 75% of the population developed some type of gastritis by 45 years of age, whereas in the low- and intermediate-risk population of Cartagena and Cali, the proportion of such lesions did not exceed 50% at age 45 or thereafter. The effect of environmental factors in early life seemed to be important in determining the prevalence of lesions in each population.

Enteropathy in adult protein malnutrition: ultrastructural findings

As part of a comprehensive study in adult patients with severe primary protein malnutrition, jejunal ultrastructural studies have been performed in nine adults in the malnourished state. Malnutrition was severe in all. D-Xylose malabsorption and abnormal fecal fat excretion were present in most. The main ultrastructural abnormalities encountered were: microvillar abnormalities such as shortening, diminished numbers, abnormal positioning, branching, and mesalike fusion of the microvilli; and abnormalities in the lamina propria characterized by deposits of osmiodense material and collagen fibers below the basement membrane of the epithelial cells and of the capillaries. None of the aforementioned findings were noted in our control cases. These ultrastructural alterations of severely malnourished adults are nonspecific, since they have already been described in other enteropathies frequently encountered in the tropics.

Enteropathy in adult protein malnutrition: light microscopic findings

Light microscopy evaluation of the intestinal abnormalities seen in 35 severely malnourished adults revealed changes which are common to other well-documented enteropathies. These included shortening, widening and fusion of the villi, lost convolution of the nuclear line, and diminished epithelial cell height. With Masson's trichrome stain, dense material was seen to have accumulated in a subepthelial location in villi (as described in other enteropathies), in crypts, and perivascularly around the capillaries of the lamina propria. Two findings however appear to characterize the severely malnourished state: a consistent, significant reduction of intestinal mucosal thickness, and in many cases atrophy of the crypts. Statistical analysis of the total mucosal thickness data does not justify five but rather three histological categories. With protein repletion as the sole therapeutic modality, 17 patients in which adequate biopsy samples were available at its completion showed significant amelioration of the aforementioned histological abnormalities, as well as normalization of their previous absorptive defects. The mild enteropathy of severe protein malnutrition must be considered in the differential diagnosis of malabsorption in a tropical setting.

Enteropathy in adult protein malnutrition: a review of the Cali experience

Since 1964, 41 patients with strictly defined, severe primary (dietetic) protein malnutrition have been studied under metabolic ward conditions during prolonged periods, initially on a low (20 g) and later on a high (100 g) protein diet. Clinical, nutritional, hematological, intestinal absorptive and histological studies were performed in the malnourished state, during and after protein repletion. Classical signs and symptoms of malnutrition, lasting for at least 4 months, were present in most patients. Mild diarrhea was frequent. All were normoblastically anemic, hypoproteinemic, and hypocholesterolemic; serum folate values were normal or low but serum B12 values were normal or high. Liver biopsy showed fatty liver in the cases where it was performed. Mild malabsorption was detected in over one-half of the patients, with moderate intestinal radiological abnormalities. Malabsorption was independent of concomitant folate deficiency. All the clinical, absorptive and histological abnormalities reversed with treatment consisting only of a high protein diet. In addition to protein lack, another factor has to be invoked in the pathogenesis of the intestinal abnormalities present in severely malnourished adults from rural areas in the tropics.

Trypanosoma cruzi and virological studies in idiopathic cardiomyopathy in Cali, Colombia

During a 10-year period a series of 114 patients was studied to determine if Trypanosoma cruzi and arboviruses could be the etiologic agents of idiopathic cardiomyopathy (ICM) in Cali, Colombia. In this area, ICM (together with rheumatic and artherosclerotic cardiopathy) represents the second most frequent cause (determined by necropsy) among adult patients with cardiopathies, hypertension being the first. No association was observed between ICM and any of the arboviruses assessed by hemagglutination tests. Only 10 of 114 cases (8.7%) showed positive seroparasitological tests for T. cruzi. Autopsy was performed in 4 of these 10 cases; 1 had Chagas myocarditis and the other 3 were patients with non-inflammatory ICM. In all 9 T. cruzi-negative cases the autopsies showed non-inflammatory ICM lesions. In contrast to typical Chagas cases, the most frequent EKG change in ICM is left bundle branch block rather than right. Since the EKG varies within either group, this distinction may not be valid in individual cases. Because of the similarities in clinical characteristics and variations in EKG between Chagas myocarditis and ICM, it is suggested that autopsies should be done in populations in endemic areas of T. cruzi to assess the frequency of ICM and its importance in the differential diagnosis of Chagas myocarditis.