Cladodes of Opuntia ficus-indica (L.) as a source of bioactive compounds in dairy products.

Recently, the interest in improving livestock product nutraceutical profiles through sustainable feeding systems has increased. In this context, the overall quality and nutraceutical profiles were examined in dairy products obtained from 16 lactating Cinisara cows given an integrated feed in dry season with Opuntia ficus-indica cladodes. Two homogeneous groups of cows (milk yield: 6.3 ± 1.5 kg; body weight: 213 ± 55 kg) were fed with 2 different diets (CON: pasture and wheat bran; OFI: pasture, wheat bran, and cladodes), according to a 2 × 2 Latin square design. The bulk milk produced during the study was used to make Caciotta cheese and was analyzed at 0, 15, and 30 storage days. Milk and cheese samples were analyzed for chemical, physical, and microbiological traits. The nutraceutical and sensorial profiles, as well as the antioxidant capacity, were also determined in the final products. For milk, the urea content in individual samples was reduced in OFI but not in CON. In the cheese, integration of cladodes did not influence the starter cultures development with 2 strains of Streptococcus thermophilus, but it caused a higher content of polyphenols and a consequent greater antioxidant capacity and a change in the fatty acids profile. In particular, the caprylic, capric, lauric, myristic, and palmitic fatty acids were higher, as were the petroselinic, vaccenic, rumenic, and α-linolenic fatty acids. In contrast, the oleic and the γ-linolenic fatty acids were lower for OFI. The cheese from the OFI group showed better overall acceptability, and a higher yellow color, odor intensity, and butter flavor. The multivariate analysis well distinguished the cheeses belonging to the 2 groups. Further investigations should be conducted to formulate well-balanced diets that include cladodes for Cinisara lactating cows, but also to determine the content of other important bioactive compounds in fresh and treated cladodes, as well as their effects on animal welfare and production.

Hallux valgus associated to osteoarthritis: Clinical-radiological outcomes of modified SERI technique at mid- to long-term follow-up. A retrospective analysis.

INTRODUCTION: Treatment of hallux valgus deformity associated with mild or moderate osteoarthritis (OA) is still a topic of debate. In the literature, there are few studies concerning the management of patients affected by this condition. This study aims to report the experience at mid- to long-term results of an original joint-preserving surgical technique. MATERIALS AND METHODS: Patients affected by mild to moderate hallux valgus deformity and associated to grade 1-2 OA and treated with modified Simple-Effective-Rapid-Inexpensive (SERI) technique from 2008 to 2018 were selected. Inclusion criteria were mild or moderate hallux valgus angle (HVA) <40° and an intermetatarsal angle (IMA) <20° and associated grade 1-2 OA of the first metatarso-phalangeal joint (MTPJ). RESULTS: 128 feet in 120 consecutive patients, undergone modified SERI procedure, have been retrospectively reviewed at a mean follow-up of 5.1 ± 3.8 years (range 2-11). American Orthopaedics Foot Ankle Society (AOFAS) score that was significantly improved from 44.2 ± 13.2 to 88.2 ± 9.6. Pre-operative average HVA and IMA values decreased respectively from 31.6° ± 3.9° to 9.1° ± 4.4° and from 16.2° ± 3.8° to 7.2° ± 3.1°. The average distal metatarsal articular angle (DMAA) value improved from 28.2° ± 6.5° to 7.1° ± 6°. OA of the first MTPJ highlighted a grade 1 in 46 feet and a grade 2 in 82 feet pre-operatively and a grade 0 in 30 feet, grade 1 in 82 feet, and grade 2 in 16 feet at the final follow-up. CONCLUSIONS: The modifications to the SERI technique could extend the indications to patients affected by hallux valgus with mild to moderate OA. The wider case series and the longer follow-up of this study make us believe this technique is very useful for improving the quality of life in these patients. LEVEL OF EVIDENCE: IV.

Comparison of elapegademase and pegademase in ADA-deficient patients and mice.

The absence of adenosine deaminase (ADA) causes severe combined immune deficiency (SCID), which has been treated with PEGylated bovine-extracted ADA (ADAGEN). ADAGEN was recently replaced by a PEGylated recombinant bovine ADA, expressed in Escherichia coli (elapegademase, ELA-ADA). Limited information on ELA-ADA is available.  ADA enzymatic activity of ELA-ADA and ADAGEN was assessed in vitro at diverse dilutions. ADA activity and immune reconstitution in an ADA-SCID patient treated with ELA-ADA were compared with age-matched patients previously treated with ADAGEN. ADA activity and thymus reconstitution were evaluated in ADA-deficient mice following ELA-ADA or ADAGEN administered from 7 days postpartum. In vitro, ADA activity of ELA-ADA and ADAGEN were similar at all dilutions. In an ADA-SCID patient, ELA-ADA treatment led to a marked increase in trough plasma ADA activity, which was 20% higher than in a patient previously treated with ADAGEN. A marked increase in T cell numbers and generation of naive T cells was evident following 3 months of ELA-ADA treatment, while T cell numbers increased following 4 months in 3 patients previously treated with ADAGEN. T cell proliferations stimulation normalized and thymus shadow became evident following ELA-ADA treatment. ADA activity was significantly increased in the blood of ADA-deficient mice following ELA-ADA compared to ADAGEN, while both treatments improved the mice weights, the weight, number of cells in their thymus and thymocyte subpopulations. ELA-ADA has similar in- vitro and possibly better in-vivo activity than ADAGEN. Future studies will determine whether ELA-ADA results in improved long-term immune reconstitution.

CO2 capture systems based on saccharides and organic superbases.

In this report, novel systems, based on highly abundant saccharides, D-mannose, D-glucose, ß-cyclodextrin, alginic acid and mannitol, in combination with an organic superbase, tetramethylguanidine (TMG) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), are studied for carbon dioxide capture. With D-mannose and D-glucose, several ratios of equivalents of alcohol groups of saccharide : superbase were tested: 1, 0.625, 0.5 and 0.25. High wt% values of CO2 uptake were obtained with TMG-based systems. However, TMG itself can react directly with CO2, and, in the presence of D-mannose, competition between carbonate and carbamate based products was established. In order to circumvent this competition and obtain exclusively the carbonate-based product, DBU was used instead as an organic superbase. In the D-mannose series the highest result was obtained with a D-mannose : DBU ratio eq. = 0.625 (13.9% CO2 uptake, 3.3/5 alcohol groups converted into carbonates). A more effective stirring system, designed to overcome the high viscosity of the products, allowed the use of a D-glucose : DBU = 1 : 1 ratio with 11.5 wt% of CO2 uptake and 2.47/5 alcohol groups converted into carbonates. Additionally a DSC thermal study was performed in order to study the stability/reversibility of the CO2 loaded systems.

Clinical results in patients affected by moderate-severe knee osteoarthritis and treated with micro-fragmented adipose tissue: the therapeutic effects on symptomatology.

Osteoarthrosis is a degenerative musculoskeletal disease that presents a major public health problem, due to the increasing average age of the active population, as well as the increasing percentage of obesity or overweight of the general population. New therapeutic approaches have been developed, such as regenerative medicine that uses mesenchymal stromal cells taken from adipose tissue. This study analyzed the clinical potential benefits of using autologous adipose tissue to treat patients with moderate-severe knee osteoarthritis.In 2021, a total of 50 knees, affected by moderate-severe knee osteoarthritis, were treated with an intra-articular injection of micro-fragmented subcutaneous adipose tissue. Patients were submitted to the KOOS questionnaire before the operation and one year after the operation and VAS pain score at time 0, 3, 6, 12 months.Of the 50 patients treated, 2 patients were excluded from the study. Of the remaining 48 patients, improvements have been achieved in all subclasses of KOOS. In particular, VAS score proves that improvements are more considerable starting from the 3rd month after surgery.The results obtained in this study show the safety and potential benefit of the use of autologous micro-fragmented adipose on people who are affected by moderate-severe knee osteoarthritis.

Orthopaedic and plastic surgery collaboration in resolution of plantar heloma and metatarsalgia using lipofilling: a retrospective evaluation.

BACKGROUND: Plantar heloma is a keratotic disorder that can be described as a circumscribed area of thickening with a central core that may penetrate the dermis. Although often considered a minor complaint, longstanding lesions can be debilitating and severely impact on person's quality of life. We present the first retrospective case series at long-term follow-up about the use of plantar lipofilling as a treatment for metatarsalgia caused by plantar heloma. MATERIALS AND METHODS: Six patients affected by plantar heloma associated to external metatarsalgia underwent plantar lipofilling. The surgical session was performed as an outpatient procedure. Clinical evaluation was performed using the AOFAS lesser metatarsophalangeal-interphalangeal (MTP-IP) score. RESULTS: Mean AOFAS lesser MTP-IP score improved from a preoperative score of 66.6 ± 3.2 points (range 47-77 points) to a post-operative score of 92.8 ± 2.7 points (range 86-95 points); all patients were satisfied with the outcome at the final follow-up. Post-operative clinical examination at final follow-up showed an increase in thickness of the subcutaneous layer and a decrease of dermal layer thanks to the supporting and trophic action of fat cells. CONCLUSIONS: Plastic regenerative procedures applicated to a typical foot and ankle surgery field, such as metatarsal overloading, metatarsalgia and forefoot problems, should be encouraged to allow new treatment horizons.

Attenuation of massive cytokine response to the staphylococcal enterotoxin B superantigen by the innate immunomodulatory protein lactoferrin.

Staphylococcal enterotoxin B (SEB) is a pyrogenic exotoxin and a potent superantigen which causes massive T cell activation and cytokine secretion, leading to profound immunosuppression and morbidity. The inhibition of SEB-induced responses is thus considered a goal in the management of certain types of staphylococcal infections. Lactoferrin (LF) is a multi-functional glycoprotein with both bacteriostatic and bactericidal activities. In addition, LF is known to have potent immunomodulatory properties. Given the anti-microbial and anti-inflammatory properties of this protein, we hypothesized that LF can modulate T cell responses to SEB. Here, we report that bovine LF (bLF) was indeed able to attenuate SEB-induced proliferation, interleukin-2 production and CD25 expression by human leucocyte antigen (HLA)-DR4 transgenic mouse T cells. This inhibition was not due to bLF's iron-binding capacity, and could be mimicked by the bLF-derived peptide lactoferricin. Cytokine secretion by an engineered SEB-responsive human Jurkat T cell line and by peripheral blood mononuclear cells from healthy donors was also inhibited by bLF. These findings reveal a previously unrecognized property of LF in modulation of SEB-triggered immune activation and suggest a therapeutic potential for this naturally occurring protein during toxic shock syndrome.

Shortening time scale to reduce thermal effects in quantum transistors.

In this article, we present a quantum transistor model based on a network of coupled quantum oscillators destined to quantum information processing tasks in linear optics. To this end, we show in an analytical way how a set of N quantum oscillators (data-bus) can be used as an optical quantum switch, in which the energy gap of the data bus oscillators plays the role of an adjustable "potential barrier". This enables us to "block or allow" the quantum information to flow from the source to the drain. In addition, we discuss how this device can be useful for implementing single qubit phase-shift quantum gates with high fidelity, so that it can be used as a useful tool. To conclude, during the study of the performance of our device when considering the interaction of this with a thermal reservoir, we highlight the important role played by the set of oscillators which constitute the data-bus in reducing the unwanted effects of the thermal reservoir. This is achieved by reducing the information exchange time (shortening time scale) between the desired oscillators. In particular, we have identified a non-trivial criterion in which the ideal size of the data-bus can be obtained so that it presents the best possible performance. We believe that our study can be perfectly adapted to a large number of thermal reservoir models.

Measurement of biofilm formation by clinical isolates of Escherichia coli is method-dependent.

AIMS: In this study, we have evaluated the impact of methodological approaches in the determination of biofilm formation by four clinical isolates of Escherichia coli in static assays. METHODS AND RESULTS: The assays were performed in microtitre plates with two minimal and two enriched broths, with one- or two-steps protocol, and using three different mathematical formulas to quantify adherent bacteria. Different biofilm formation patterns were found depending on the E. coli strain, culture medium and reading optical density on one- and two-steps protocol. Strong or moderate biofilm formation occurred mostly in minimal media. The mathematical formulas used to quantify biofilm formation also gave different results and bacterial growth rate should be taken into account to quantify biofilm. CONCLUSIONS: Escherichia coli forms biofilms on static assays in a method-dependent fashion, depending on strain, and it is strongly modulated by culture conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: As verified in the studied E. coli strains, biofilm formation by any organism should be cautiously interpreted, considering all variables in the experimental settings.

Using assistive robots to promote inclusive education.

PURPOSE: This paper describes the development and test of physical and virtual integrated augmentative manipulation and communication assistive technologies (IAMCATs) that enable children with motor and speech impairments to manipulate educational items by controlling a robot with a gripper, while communicating through a speech generating device. METHOD: Nine children with disabilities, nine regular and nine special education teachers participated in the study. Teachers adapted academic activities so they could also be performed by the children with disabilities using the IAMCAT. An inductive content analysis of the teachers' interviews before and after the intervention was performed. RESULTS: Teachers considered the IAMCAT to be a useful resource that can be integrated into the regular class dynamics respecting their curricular planning. It had a positive impact on children with disabilities and on the educational community. However, teachers pointed out the difficulties in managing the class, even with another adult present, due to the extra time required by children with disabilities to complete the activities. CONCLUSIONS: The developed assistive technologies enable children with disabilities to participate in academic activities but full inclusion would require another adult in class and strategies to deal with the additional time required by children to complete the activities. Implications for Rehabilitation Integrated augmentative manipulation and communication assistive technologies are useful resources to promote the participation of children with motor and speech impairments in classroom activities. Virtual tools, running on a computer screen, may be easier to use but further research is needed in order to evaluate its effectiveness when compared to physical tools. Full participation of children with motor and speech impairments in academic activities using these technologies requires another adult in class and adequate strategies to manage the extra time the child with disabilities may require to complete the activities.

EFFICIENCY STUDY OF A LEGe DETECTOR SYSTEM FOR THE ASSESSMENT OF 241Am IN SKULL AT CIEMAT WHOLE BODY COUNTER.

(241)Am incorporation due to an incident or chronic exposure causes an internal dose, which can be evaluated from the total activity of this isotope in the skeleton several months after the intake. For this purpose, it is necessary to perform in vivo measurements of this bone-seeker radionuclide in appropriate counting bone geometries with very low attenuation of surrounded tissue and to extrapolate to total activity in the skeleton (ICRP 89, Basic anatomical and physiological data for use in radiological protection: reference values. 2001. 265). The work here presented refers to direct measurements of americium in the Cohen skull phantom at the CIEMAT Whole Body Counter (WBC) using low-energy germanium (LEGe) detectors inside a shielding room. The main goal was to determinate the most adequate head counting geometry for the in vivo detection of americium in the bone. The calibration of the in vivo LEGe system was performed with four detectors with 2 cm of distance to Cohen phantom. Two geometries were measured, on junction of frontal to parietal bones and frontal bone. The efficiencies are very similar in both geometries, the preferred counting geometry is the most comfortable for the person, with the LEGe detectors in the highest part of the frontal bone, near the junction with the parietal bone, CIEMAT WBC participated in a skull intercomparison exercise organised by WG7 of EURADOS (European Radiation Dosimetry Group e.V.). Efficiencies using three different skull phantoms were obtained. Measurements were performed for different head counting positions, four of them in the plane of symmetry and others over the temporal bone. The detector was placed in parallel with the calibration phantom at a distance of 1 cm. The main gamma emission of (241)Am, 59.5 keV (36 %), was used for comparing efficiency values. The lower efficiency was obtained over the frontal and occipital bones. Measurement with one LEGe detector over the parietal bone is the most efficient. The activity of each skull phantom was calculated using CIEMAT head calibration. Results of the EURADOS intercomparison are presented here for discussion.

Prosthetic valve endocarditis caused by Brucella melitensis. A report of four cases successfully treated with tetracycline, streptomycin, and sulfamethoxazole and trimethoprim plus valve replacement.

Optimal treatment of prosthetic valve endocarditis due to Brucella melitensis is unknown. The presence of ring abscess makes extensive surgical débridement and valve replacement essential steps of management. Antimicrobial therapy with tetracycline hydrochloride plus streptomycin sulfate or sulfamethoxazole and trimethoprim can achieve the sterilization of infected cardiac tissue. Late bland periprosthetic leaks occur frequently. Reoperation can be safely performed after a period of antimicrobial therapy. Prolonged treatment with doxycycline hyclate seems advisable.

T lymphocytes possess the machinery for 5-HT synthesis, storage, degradation and release.

AIM: Although activated T lymphocytes express tryptophan hydroxylase 1 and produce 5-HT, the metabolic fate and cellular handling of this 5-HT is unclear. Here, we investigated key proteins in T cells linked to 5-HT metabolism and storage and compare differences in 5-HT synthesis and metabolism between T-cell subsets. METHODS: We cultured human Jurkat T cells and mouse splenic CD3(+) , CD4(+) and CD8(+) T cells with or without T-cell activators (phorbol ester/ionomycin, concavalin A or plate-bound anti-CD3 antibody). Subsequently, we measured mRNA and/or protein for monoamine oxidase A and B, vesicular monoamine transporter 1 and 2, N-acetyl transferase and tryptophan hydroxylase 1. In addition, we measured the release of exogenously loaded [(3) H]5-HT and endogenously synthesized 5-HT from CD4(+) and CD8(+) T-cell subsets. RESULTS: Human and mouse T cells selectively express monoamine oxidase A. Following T-cell activation, mRNA levels of MAO-A increase robustly in parallel with tryptophan hydroxylase 1. Concomitant with these changes, T cells increase the expression of the type 1 vesicular monoamine transporter. Raised intracellular [Ca(2+) ] rapidly releases preloaded [(3) H]5-HT from CD4(+) and CD8(+) T cells indicating that these cells have the capacity for the storage and regulated secretion of 5-HT. Notably, both the expression of tryptophan hydroxylase 1 and monoamine oxidase A, and 5-HT production are significantly greater in CD8(+) compared with CD4(+) T cells. CONCLUSION: These data reveal coordinated changes in 5-HT production, metabolism and storage that may optimize 5-HT secretion from the CD8(+) T cell subset in response to activation stimuli.

First description of endemic HTLV-II infection among Venezuelan Amerindians.

We describe for the first time the presence of human T lymphotropic virus type II (HTLV-II) infection in Venezuela, among the Pume Amerindians living in the southern plains of the country. Antibodies to HTLV-II antigens were assessed by enzyme immunoassays (Elisa), Western blot, radioimmuno-precipitation, and immunofluorescence; titration studies against HTLV-I- and HTLV-II-infected cell lines were very useful in the differentiation of HTLV-I and HTLV-II antibodies. The HTLV-II general prevalence was 5%; however, there is a striking difference in prevalence between the truly isolated villages (0%) when compared to those living along the riverside and thus in contact with outsiders (9%). Preliminary evidence suggests sexual contact as the main source of transmission. These findings might suggest that HTLV-II in Venezuela originated through contact with outsiders rather than ancient infection related to the origins of the Pume.

Expression of HLA class I-specific inhibitory receptors in human cytolytic T lymphocytes: a regulated mechanism that controls T-cell activation and function.

Different families of major histocompatibility complex (MHC)-specific inhibitory receptors (NKRs) play a major role in natural killer (NK) cell function, allowing discrimination between normal cells and cells that do not express adequate amounts of MHC class I antigens. This occurs in most instances as a consequence of viral infection or tumor transformation. In T lymphocytes, expression of NKR is mostly confined to activated CD8+ cytolytic T lymphocytes (CTLs). While NKR expression by CTLs may be viewed as a mechanism preventing damages to normal cells by those CTLs that have acquired NK-like activity, it may also down regulate TCR-mediated T cell activation, thus, impairing CTL functions. The finding that certain cytokines can modulate killer inhibitory receptor expression in CTLs is of major interest and might be instrumental in novel therapeutic approaches aimed at the down regulation ofT-cell function in transplantation or autoimmunity.

Analysis of HIV type 1 protease and reverse transcriptase sequences from Venezuela for drug resistance-associated mutations and subtype classification: a UNAIDS study.

We report the first study on prevalence of antiretroviral drug-associated resistance mutations in Venezuela. Protease and reverse transcriptase (RT) coding regions were analyzed in DNA samples obtained from 100 HIV-1-infected individuals. Primary resistance mutations to RT inhibitors were identified in 26% of patients treated with these drugs. Transmission of HIV-1-resistant strains was detected in a drug-naive patient (3%). Primary resistance mutations to protease inhibitors (PIs) were present in 9% of the 44 PI-treated patients and in 1 PI-naive individual. Phylogenetic analysis of these samples has resulted in the most extensive survey, to date, of HIV-1 genetic forms circulating in Venezuela. Ninety-nine samples clustered with subtype B, and 1 individual harbored the first B/F recombinant virus reported in Venezuela, with protease clustering with subtype F and RT with subtype B. In addition, this isolate had a new insertion (Glu-34 duplication) in the protease gene.

Immunotherapy with the use of tumor-infiltrating lymphocytes and interleukin-2 as adjuvant treatment in stage III non-small-cell lung cancer. A pilot study.

This study assesses the feasibility and toxicity of adoptive immunotherapy with tumor infiltrating lymphocytes and recombinant interleukin-2 in 29 patients who underwent resection for stage III non-small-cell lung cancer. In five patients cultures yielded no growth of tumor infiltrating lymphocytes. In the remaining 24 patients (stage IIIa, 14 cases; stage IIIb, 10 cases) tumor infiltrating lymphocytes were in vitro expanded from surgically obtained tissue samples, including samples from both the tumor and surrounding lung. A number of tumor infiltrating lymphocytes, ranging from 4 to 70 billion cells, were reinfused intravenously 4 to 6 weeks after operation. Interleukin-2 was administered subcutaneously at escalating does for 2 weeks and then at reduced doses for 2 to 3 months. Median survival was 14 months, and the 2-year survival was 40%. Three patients remain alive and disease-free at more than 2 years after operation. Two of these patients did not have complete resection at thoracotomy. Multivariate analysis showed no correlation between the factor of incomplete resection and survival. Intrathoracic recurrence without concomitant distant failure was documented in two patients only and none of the patients with incomplete resection (12 cases) had relapse within the thorax. The present experience demonstrates that adoptive immunotherapy may be applied with safety in patients operated on for stage III non-small-cell lung cancer and suggests that it can be useful, notably in patients with locally advanced disease.

Phenotypic and functional analysis of the HLA-class I-specific inhibitory receptors of natural killer cells isolated from peripheral blood of patients undergoing bone marrow transplantation from matched unrelated donors.

INTRODUCTION: Limited information is available on the natural killer cell reconstitution after bone marrow transplantation and on the possible role of these cells in graft-versus-host-disease. MATERIALS AND METHODS: Blood samples were collected at different time intervals after transplantation. Lymphocytes were analyzed for informative markers by immunocytofluorimetric analysis. Natural killer cells derived from patients undergoing matched unrelated donor transplant were cloned by limiting dilution in the presence of phytohemoagglutinin and IL2. The natural killer cell clones were analyzed for cytolytic activity. RESULTS: In the nine patients analyzed undergoing transplantation from sibling donors, the majority of peripheral blood lymphocytes during the first 80 d after BMT were represented by T lymphocytes, while in the 15 patients undergoing matched unrelated donor transplant natural killer cells consistently outnumbered T lymphocytes. During the early phases after transplantation, most CD56+CD3- natural killer cells did not express CD16 which was expressed at later intervals. Analysis of the inhibitory receptors specific for HLA-class I molecules showed that CD94/NKG2A, specific for HLA-E, unlike normal donors, was expressed by all natural killer cells including the early appearing CD16-negative ones. Killer inhibitory receptors of the Ig superfamily were expressed late and in low percentages after transplantation and were always coexpressed with CD94/NKG2A. Natural killer-cell clones efficiently lysed the HLA-class I-negative cell lines K562 and 721-221. Natural killer-cell populations or clones isolated from patients with graft-versus-host-disease, failed to lyse donor or recipient derived phytohemoagglutinin-induced lymphoblasts. CONCLUSION: Our analysis shows that (1) recipients of matched unrelated donors transplants exhibit a high proportion of NK cells (2) all NK cells express CD94/NKG2A while the HLA-class I-specific inhibitory receptors of Ig superfamily appear at later stages and (3) donor NK cells do not lysed donor or recipient target cells.

Reciprocal antimicrobial synergism between Escherichia coli and Bacteroides fragilis in the presence of metronidazole.

We have studied the antimicrobial action of metronidazole against Bacteroides fragilis and Escherichia coli both in pure cultures and in combination. Concentrations of metronidazole above the minimal inhibitory concentration (MIC) produced a marked bactericidal effect on B fragilis at six hours. E coli however showed only a slight and transitory decrease in population when exposed to concentrations of metronidazole close to its MIC. Kinetic studies of this drug's effect on mixed cultures of both organisms showed mutual bactericidal synergy between E coli and metronidazole against B fragilis and between B fragilis and metronidazole against E coli. These in vitro findings agree with the results obtained in vivo by other authors.