Mediastinitis of odontogenic origin. A serious complication with 80 years of history

We performed a systematic review of the literature about descending necrotising mediastinitis (DNM) of odontogenic origin. In parallel, a retrospective review of this pathology was carried out in an Oral and Maxillofacial Surgery Service of a reference hospital for a population of 1,100,000 inhabitants. The main objectives were to determine changes in mortality and prevalence of this serious complication. The systematic review included 51 articles with 89 patients and our study comprised seven patients. The period of time with the highest number of cases was between 2000-2009 (38 patients). The percentage of mortality observed was 20.2% in diffuse DNM and 4.9% in localised DNM. Thirty-one patients with DNM in our review were admitted for more than 41 days. Despite evidence of a decrease in DNM cases, publications have increased over the years, but it does not appear to be due to an increase in those of odontogenic origin. The survival of DNM has improved since 1998 and remained stable since then. Despite the low prevalence of this disease, multicentre control studies are needed to achieve better evidence about this entity.

Knowledge, attitudes and beliefs on organ donation among students and lecturers in Quito, Ecuador

Countries have reported that people's attitudes towards organ donation are influenced by knowledge, education and religion. In Ecuador, more than 800 patients are on the waiting list for an organ; likewise, the population does not recognize the importance of the donation. Although, since 2011, the Organic Law of Donation and Transplantation of Organs, Tissues and Cells states that all Ecuadorians are donors, but still, the high number of people on the waiting list is not well understood. The purpose of this study is to determine the factors towards organ donation of students and lecturers of the Pontifical Catholic University of Ecuador. This is a cross-sectional study, and the universe was the entire population; however, only 469 (students) and 321 (lecturers) answered, despite our efforts. We applied an anonymously validated questionnaire, and we sent it for five months by email. 89.8% of students and lecturers agreed with the donation; however, 10.2% of the students refused, and 14.6% of lecturers were undecided (p < 0.001). The highest hesitation was found in the age group between 36-64 years (14.2%), while the most refusal was found in the young adult, 9.4%. 40.1% of them alluded to have regular knowledge, while 27.9% claimed to have low knowledge about organ donation (p = 0.016). Based on their opinion, 65.9% said that a person with brain death could not recover, although 26.9% did not know (p = 0.023). 38.9% affirmed they did not know if their religions agreed with the donation. 78.5% claimed the best methods could increase the number of donors is education. Public health in Ecuador does not have sufficient regulations through its state policies that should favour recipients. If each citizen knows that their organs save lives, the waiting list will decrease, and state expenditures will reduce. However, the populations' beliefs are still related to an abuse of authority to donate organs without the consent of relatives.

Key messages

With better strategies to increase awareness of the importance of organ donation, great results. It will increase survival rates, improve quality of life and decrease health expenses.

Epigenetic control of the EWS‑FLI1 promoter in Ewing's sarcoma

Ewing sarcoma (ES) is a primary bone marrow tumor that very rarely develops in extra-osseous tissues, such as lung. The hallmark of ES tumors is a translocation between chromosomes 11 and 22, resulting in a fusion protein, commonly referred to as EWS-FLI1. The epigenetic profile (histone acetylation and methylation enrichment of the promoter region) that may regulate the expression of the aberrant transcription factor EWS-FLI1, remains poorly studied and understood. Knowledge of epigenetic patterns associated with covalent histone modification and expression of enzymes associated with this process, can contribute to the understanding of the molecular basis of the disease, as well as to the identification of possible molecular targets involved in expression of the EWS-FLI1 gene, so that therapeutic strategies may be improved in the future. In the present study, the transcriptional activation and repression of the EWS-FLI1 fusion gene in ES was accompanied by selective deposition of histone markers on its promoter. The EWS-FLI1 fusion gene was evaluated in two patients with ES using conventional cytogenetic, fluorescence in situ hybridization and nested PCR assays, which revealed that the aberrant expression of the EWS-FLI1 gene is accompanied by enrichment of H3K4Me3, H3K9ac and H3K27ac at the promoter region.

Spotlight on esophageal perforation: A multinational study using the Pittsburgh esophageal perforation severity scoring system

OBJECTIVE

The Pittsburgh group has suggested a perforation severity score (PSS) for better decision making in the management of esophageal perforation. Our study aim was to determine whether the PSS can be used to stratify patients with esophageal perforation into distinct subgroups with differential outcomes in an independent study population.

METHODS

In a retrospective study cases of esophageal perforation were collected (study-period, 1990-2014). The PSS was analyzed using logistic regression as a continuous variable and stratified into low, intermediate, and high score groups.

RESULTS

Data for 288 patients (mean age, 59.9 years) presenting with esophageal perforation (during the period 1990-2014) were abstracted. Etiology was spontaneous (Boerhaave; n = 119), iatrogenic (instrumentation; n = 85), and traumatic perforation (n = 84). Forty-three patients had coexisting esophageal cancer. The mean PSS was 5.82, and was significantly higher in patients with fatal outcome (n = 57; 19.8%; mean PSS, 9.79 vs 4.84; P < .001). Mean PSS was also significantly higher in patients receiving operative management (n = 200; 69%; mean PSS, 6.44 vs 4.40; P < .001). Using the Pittsburgh strata, patients were assigned to low PSS (≤2; n = 63), intermediate PSS (3-5; n = 86), and high PSS (>5; n = 120) groups. Perforation-related morbidity, length of stay, frequency of operative treatment, and mortality increased with increasing PSS strata. Patients with high PSS were 3.37 times more likely to have operative management compared with low PSS.

CONCLUSIONS

The Pittsburgh PSS reliably reflects the seriousness of esophageal perforation and stratifies patients into low-, intermediate-, and high-risk groups with differential morbidity and mortality outcomes.

Surgery for parapneumonic pleural empyema--What influence does the rising prevalence of multimorbidity and advanced age has on the current outcome?

OBJECTIVE

Pleural empyema is a critical condition. In the western world the share of sufferers with multiple comorbidities and advanced age is rapidly increasing.

METHODS

This retrospective study comprises all patients who underwent surgery for parapneumonic pleural empyema at a major center for thoracic surgery in Germany between January 2006 and April 2013.

RESULTS

A total of 335 patients (mean age 60.4 years) were included. The average ASA grade was 2.8. Empyema stage 1, 2 and 3 (classification of the American Thoracic Society) was encountered in 30, 230 and 75 cases, respectively. The most common comorbidities were cardiac disorders (124), diabetes mellitus (76), COPD (66) and alcoholism (54). The mean Charlson index of comorbidity score was 2. Minimally invasive surgery was feasible in 290 cases. A total of 88 patients sustained pulmonary sepsis. The overall mortality was 29/335 (8.7%). The occurrence of pulmonary sepsis (OR: 17.95; 95% CI: 6.38-62.69; p < 0.001), respiratory failure (OR: 23.08; 95% CI: 8.52-73.35; p < 0.001) and acute renal failure (OR: 8.20; 95% CI: 3.18-20.80; p < 0.001) and Charlson score ≥ 3 (OR: 6.65; 95% CI: 2.76-17.33; p < 0.001) were associated with higher mortality. On the other hand, very elderly sufferers (≥80 years) showed neither higher odds for pulmonary sepsis (OR: 0.78) nor for fatal outcome (OR: 0.92; 95% CI: 0.22-2.86; p = 1).

CONCLUSIONS

Parapneumonic pleural empyema is still associated with considerable morbidity and mortality. Pre-existing comorbidity, the occurrence of pulmonary sepsis and sepsis related complications have a determining influence on the results whereas advanced age itself shows no higher risk for adverse outcome. Further improvement seems achievable by earlier surgical intervention before the onset of pulmonary sepsis.

Electronic nose for the identification of pig feeding and ripening time in Iberian hams

An electronic nose system to control the processing of dry-cured Iberian ham is presented. The sensors involved are tin oxide semiconductors thin films. They were prepared by RF sputtering. Some of the sensors were doped with metal catalysts as Pt and Pd, in order to improve the selectivity of the sensors. The multisensor with 16 semiconductor sensors, gave different responses from two types of dry-cured Iberian hams which differ in the feeding and curing time. The data has been analysed using the PCA (principal component analysis) and backpropagation and probabilistic neural networks. The analysis shows that different types of Iberian ham can be discriminated and identified successfully.

[Appropriateness of treating glaucoma suspects. Concordancy study with the RAND study group]

OBJECTIVE

The Appropriateness of Treating Glaucoma Suspects Study Group proposes to identify which patients suspected of glaucoma are suitable for treatment. Our objective is to analyse the concordance between our clinical decisions and this Study Group.

METHODS

Retrospective study of 77 patients (39 suspects, 38 ocular hypertensives). Variables such as age, family history, intraocular pressure, disc size, cup-to-disc ratio, central corneal thickness and life expectancy were collected.They were scored following the Appropriateness of Treating Glaucoma Suspects Scale. Whether there was a consensus to treat or not depended on this value. The kappa index was used to measured the concordancy.

RESULTS

The kappa index was 0.082 (95% confidence interval between -0.11 and 0.27). Total concordancy was obtained in 41 patients (63,08%). We decided to treat 25 patients (22 of which were not treated by the experts) and not to treat 40 patients (2 of which were treated by the experts). In 12 patients there was noconsensus by the experts to treat, but we decided to treat 8 of them.

CONCLUSIONS

[corrected] The concordancy index was low. Others variables such as visual fields and Heidelberg Retina Tomography (HRT III) parameters were not collected by the experts but were important in our decisions. There are no clinical guidelines on suspects. Individualised decisions are still necessary.

[Osmophobia analysis in primary headache]

INTRODUCTION

Osmophobia is often reported by migraine patients. This study evaluates osmophobia in connection with the diagnosis of episodic migraine with or without aura, chronic migraine and episodic and chronic tension-type headache.

METHODS

We recruited from our Headache Unit 68 patients (59 female, 9 male; age 37+/-14.7 years), of whom 24 were migraine without aura (MoA), 11 migraine with aura (MA), 10 chronic migraine (CM) and 23 TTH (episodic-TTH). Patients with two or more forms of primary headache were excluded.

RESULTS

Among migraine patients, 54% with MoA and 0% with MA, 40 %CM reported osmophobia during the attacks; none of the 23 TTH patients suffered this symptom. The crisis frequency was MoA and osmophobia 2.15 crisis per month; MoA without osmophobia 3,14. MC with osmophobia 22; MC without osmophobia 21.7.

CONCLUSIONS

Osmophobia and taste abnormalities were demonstrated to be very specific in diagnosing migraine, but very insensitive. Osmophobia frequency does not depend on migraine frequency. Osmophobia seems to be more frequent in females than in males. The lack of osmophobia in MA patients could be explained by a different pathophysiological mechanism between MA and MoA.

[Fuchs' heterochromic cyclitis without heterochromia: a diagnostic approach]

OBJECTIVE

To obtain diagnostic guidelines of Fuchs' heterochromic cyclitis (FHC) in the absence of heterochromia using Bayesian methods.

METHODS

The pre-test and post-test likelihood that a certain patient without heterochromia (but with other characteristic symptoms of the disease such as iris nodules, cataracts, glaucoma or vitritis) has FCH, was assessed by the Bayes' theorem for conditioned likelihood. The prevalence values of FCH and the presentation rate of symptoms in FCH and in other forms of anterior uveitis were obtained from published literature data.

RESULTS

In the absence of heterochromia, the combination of iris nodules together with cataracts, vitritis or glaucoma, and the association of the last three symptoms in the absence of nodules, resulted in an accumulated likelihood of more than 50% of subjects having the disease.

CONCLUSIONS

The coincidence in one patient of several indicative symptoms, even in the absence of heterochromia, may make FCH a likely diagnostic option.

[Have patients who go to the emergency department changed? Evolutive study for the years 1997 and 2005]

OBJECTIVE

To study the change in number and profile of patients who came to the Emergency Department of a level 2 hospital with ophthalmic emergencies in the years 1997 and 2005.

METHOD

Two groups of randomly selected patients who came to the Emergency Service on the same day in the years 1997 and 2005 were studied. The study focused on the following variables: number of visits per day, gender, age, time period, number of examinations done, diagnoses and type of treatment prescribed. Comparison of proportions was carried out with a confidence interval study and Chi Square Test.

RESULTS

The statistically significant changes (p<0.05) were as follows: increase in number of patients seen; increase in the diagnosis of corneal foreign body (25%); decrease in the diagnosis of conjunctivitis (12%); increase in cases in which only one examination was done (19%); increase in frequency of visits between 6 p.m. and 9 p.m. and decrease between 9 a.m. and 12 p.m; reduced attendance of those of female gender (13%) and increase in the male gender (13%); increase in patients between the age of 31 and 40 years (9%); decrease in the use of treatments such as occlusion and epithelializing ointment (7% and 6% respectively); increase in use of analgesics (5%), artificial tears (5%) and NSAIDs (8%); increase in referral of patients to their primary care physician (17%) and decrease in ophthalmology check ups (34%).

CONCLUSIONS

The number of ophthalmological emergencies has increased in the last eight years, especially in young male patients, with work-related disease, who came in the evening. Treatments such as the use of artificial tears have increased, and patients are sent to the primary care physician more often.

[Migration and extrusion from the upper digestive tract to the skin of the neck of a foreign body (fish bone)]

Foreign bodies ingestion is a common problem seen at emergency rooms and mostly involved are fish and chicken bones. The diagnosis can be difficult because of the age of the patient (children and older patients with dental prosthesis). The shape of the foreign body leds to the course of the pathology, with possible mayor complications like migration into the fascial spaces of the neck, retropharyngeal abscess and perforation of the pharynx or esophagus which have the potential to cause morbidity and mortality. We present a 88-year-old lady who swallowed a 3 cm linear sharp fish bone which migrated from the pharynx to the skin of the neck, surfaced through a fistulous orifice and threw out six weeks later. No intervention was needed. A discussion of the management of migrated foreign bodies follows.

Sustained virological response to peginterferon plus ribavirin in chronic hepatitis C genotype 1 patients is associated with a persistent Th1 immune response

BACKGROUND

An impairment of cellular immune response may contribute to the persistency of hepatitis C virus infection.

AIM

To analyse the Th1/Th2 cytokine profile in peripheral blood CD4(+) and CD8(+) T cells from patients with chronic hepatitis C (CHC) during treatment with pegylated interferon-alpha2a plus ribavirin and to correlate the Th1/Th2 balance with virological response (SVR).

METHODS

Prospective longitudinal study: 44 naïve genotype 1 CHC patients received PEG-IFNalpha2a plus ribavirin for 48 weeks: 26 (59.1%) achieved a SVR, 13 relapsed (29.5%) and 5 (11.4%) were non-responders. Sixteen healthy controls were analysed. The production of IL-4, IFNgamma and TNFalpha by CD4(+) and CD8(+) T cells was measured using flow cytometry, both in resting and phorbol-ester-stimulated cells.

RESULTS

First three months of treatment: the synthesis of TNFalpha by phorbol-ester-stimulated-CD4(+) T cells was higher in patients with SVR (P < 0.01). At the end of treatment, SVR was associated with higher intracellular expression of IFNgamma by stimulated-CD4(+) and CD8(+) T cells (P < 0.05). At the end of follow-up, a higher intracellular expression of IFNgamma by CD4(+) T cells was associated with a SVR.

CONCLUSIONS

A Th1-type immune response was associated with achievement of a SVR, as indicated by the persistent elevation of intracellular IFNgamma and TNFalpha.

Differentiation of red wines using an electronic nose based on surface acoustic wave devices

An electronic nose, utilizing the principle of surface acoustic waves (SAW), was used to differentiate among different wines of the same variety of grapes which come from the same cellar. The electronic nose is based on eight surface acoustic wave sensors, one is a reference sensor and the others are coated by different polymers by spray coating technique. Data analysis was performed by two pattern recognition methods; principal component analysis (PCA) and probabilistic neuronal network (PNN). The results showed that electronic nose was able to identify the tested wines.

Effects of clarification and filtration processes on the removal of fungicide residues in red wines (var. Monastrell)

The effects of six clarification agents (egg albumin, blood albumin, bentonite plus gelatin, charcoal, PVPP, and silica gel) on the removal of residues of four fungicides (cyprodinil, fludioxonil, pyrimethanil, and quinoxyfen) applied directly to a racked red wine, elaborated from Monastrell variety grapes from the D.O. region of Jumilla (Murcia, Spain), are studied. The clarified wines were filtered with 0.45 microm nylon filters to determine the influence of this winemaking process in the disappearance of fungicide residues. Analytical determination of cyprodinil, fludioxonil and pyrimethanil was performed by gas chromatography with an alkaline thermoionic detector (NPD), whereas that of quinoxyfen using an electron captor detector (ECD). In general, and for all of the fungicides except quinoxyfen, blood albumin has proved to be the most effective clarifying agent in the removal of residues, whereas silica gel proved to be ineffective against all of the pesticides with the exception of fludioxonil. Quinoxyfen is the least persistent fungicide in the clarified wines and that which appears with highest frequency in the lees. In general, filtration is not an effective step in the elimination of wine residues. The greatest elimination after filtration is obtained in wines clarified with charcoal and the lowest in those clarified with PVPP.

A linkage map of chickpea (Cicer arietinum L.) based on populations from Kabuli x Desi crosses: location of genes for resistance to fusarium wilt race 0

Two recombinant inbred line (RIL) populations derived from intraspecific crosses with a common parental line (JG62) were employed to develop a chickpea genetic map. Molecular markers, flower colour, double podding, seed coat thickness and resistance to fusarium wilt race 0 (FOC-0) were included in the study. Joint segregation analysis involved a total of 160 markers and 159 RILs. Ten linkage groups (LGs) were obtained that included morphological markers and 134 molecular markers (3 ISSRs, 13 STMSs and 118 RAPDs). Flower colour (B/b) and seed coat thickness (Tt/tt) appeared to be linked to STMS (GAA47). The single-/double-podding locus was located on LG9 jointly with two RAPD markers and STMS TA80. LG3 included a gene for resistance to FOC-0 (Foc0(1)/foc0(1)) flanked by RAPD marker OPJ20(600) and STMS marker TR59. The association of this LG with FOC-0 resistance was confirmed by QTL analysis in the CA2139 x JG62 RIL population where two genes were involved in the resistance reaction. The STMS markers enabled comparison of LGs with preceding maps.

Fungicide dissipation curves in winemaking processes with and without maceration step

The evolution of residual levels of four fungicides (cyprodinil, fludioxonil, pyrimethanil, and quinoxyfen) during the elaboration of three types of wine with maceration (traditional red wine, carbonic maceration red wine, and red wine of long maceration and prefermentation at low temperature) and two types of wine without maceration (rose and white) has been studied. The disappearance curves of each fungicide have been analyzed during the period of each winemaking process (21 days) and during the different enological steps involved in the elaborations. The residual levels of fludioxonil reduce most quickly during the winemaking processes without maceration, whereas the decrease in levels of pyrimethanil was the slowest in practically all cases (with and without maceration). During carbonic maceration winemaking, the decay constant of cyprodinil was greater than that of the other pesticides in all assays (time and steps).

[Tubulointerstitial nephritis associated with treatment with selective Cox-2 inhibitors, celecoxib and rofecoxib]

The nephrotoxic effect of nonselective nonsteroidal anti-inflamatory drugs (NSAIDS) has been widely described. The main benefit of the Cox-2 inhibitors in relation to the NSAIDS is the production of a very similar analgesic effect, but with fewer gastrointestinal side effects. However, their effects on renal function are little known as yet and their long-term safety is still pending definition. The use of selective Cox-2 inhibitors as anti-inflamatory analgesic is becoming more and more common in our environment. We report two cases of tubulointersticial nephritis confirmed by renal biopsy, associated with administration of the two Cox-2 inhibitors currently available on the market, celecoxib and rofecoxib. In both cases, we were talking about elderly women, with deterioration of the general condition and acute renal failure. In the former case, renal biopsy showed an acute tubulo-intersticial nephritis (TIN) so highly "variegated" in its histologic expression. In the second case, was associated with strong indications of chronicity. Treatment with steroid was initiated in both patients and improvement of renal function was observed.

Apoptosis induced by different doses of caffeine on Chinese hamster ovary cells

Caffeine has been investigated for its potential mutagenic activity to bacteria, fungi and mammalian cells in culture, and at high concentrations it is also an inducer of apoptosis. Caffeine can exert acute cellular toxicity, including inhibition of cell growth and cell death, in Chinese hamster ovary cells. The aim of this study was to evaluate the cell survival and apoptotic or non-apoptotic effects of caffeine to different concentrations in Chinese hamster ovary cells (CHO-K1). These effects were evaluated by measuring cell viability, caspase 8 activity and fragmented DNA. This study suggests that the concentration of caffeine is of critical importance because high doses of caffeine induce apoptosis and low concentrations can act as an antioxidant. Previously, the cytotoxicity of caffeine was evaluated using a wide range of concentrations by the neutral red test. From this screening, adequate doses were selected to perform the caspase activity and fragmentation DNA studies. The potential antioxidant effect of caffeine was studied using tert-butyl-hydroperoxide as a free-radical generator. The repeatability was checked through three separate tests with the same concentration.

[Parotid tuberculosis following intravesical BCG instillation: a case report]

First case of parotid gland tuberculosis publicated to date is presented after intravesical instillation of BCG for a superficial bladder cancer. The diagnosis of the parotid gland tuberculosis is difficult because it is usually indistinguishable from a neoplasm. Combined fine-needle aspiration cytology with PCR or LCR amplification of mycobacterial DNA could be a good diagnostic tool avoiding an open biopsy.

Early infections in adult patients undergoing unrelated donor cord blood transplantation

Early transplant-related mortality after cord blood transplantation from unrelated donors (UD-CBT) is close to 50%, mainly due to infectious complications. We have studied the incidence and characteristics of early infections (before day 100) in a series of 27 adult patients (median age 30 years, range 16-46) undergoing UD-CBT at a single institution. All 27 patients experienced at least one infectious episode and 18 (66%) suffered a severe infection. Bacteremia occurred in 55% of patients (13 with Gram-positive and 11 with Gram-negative microorganisms). Eleven of 19 CMV-seropositive patients (58%) developed CMV antigenemia and one patient had CMV disease. Fungal infections were documented in three patients (11%), comprising invasive fungal infections in two cases and a localized esophagitis in one. Ten patients (37%) died before day 100 after transplantation. Infection was considered the primary cause of death in four patients (sepsis by Acinetobacter spp. bacteremia in three cases) and contributed to death in another four. The most striking findings in this series were the high incidence of, and mortality due to multiresistant Acinetobacter spp. and the low incidence of and lack of mortality due to CMV disease. This report confirms that infection is a major complication in adults undergoing UD-CBT.

In vitro toxicity of stimulant soft drinks

Some drinks containing natural products with stimulant properties are highly consumed among young adults. The market for these drinks has increased in past years around the globe, and, although they might be harmless, overdoses or combination of these with other drinks could be harmful to the health of some consumers in certain circumstances. Samples were obtained at food shops and different popular brands were chosen. Cytotoxicity tests used were neutral red uptake, total protein content, and tetrazolium assay on Chinese hamster ovary cells. Results revealed that tested samples were not cytotoxic; however, studies have demonstrated the toxicity of high concentrations of some of these products. For this reason, the authors considered it to be of critical importance to carryout an in vitro toxicity screening of stimulant soft drinks that are highly consumed.

[Transesophageal echocardiographic diagnosis of a ruptured sinus of valsalva aneurysm with right atrium fistula]

Congenital aneurysms of the sinus of Valsalva are relatively rare, tending to be most frequent in adults. Untreated, there is a substantial risk of complication due to bacterial endocarditis and, if rupture occurs, rapid and progressive cardiac insufficiency is fatal at short term. We report the case of a 53-year-old male with a ruptured right sinus of Valsalva aneurysm, resulting in an anomalous right atrium fistula. Symptoms presented, clinical diagnosis and, above all, transesophageal echocardiography were crucial in the final diagnosis leading to an early and satisfactory surgical intervention. Catheterization and angiography were not definitive. Echocardiographic data are described and a bibliography of relevant research articles is provided.

The mtmVUC genes of the mithramycin gene cluster in Streptomyces argillaceus are involved in the biosynthesis of the sugar moieties

Mithramycin is a glycosylated aromatic polyketide produced by Streptomyces argillaceus, and is used as an antitumor drug. Three genes (mtmV, mtmU and mtmC) from the mithramycin gene cluster have been cloned, and characterized by DNA sequencing and by analysis of the products that accumulate in nonproducing mutants, which were generated by insertional inactivation of these genes. The mtm V gene codes for a 2,3-dehydratase that catalyzes early and common steps in the biosynthesis of the three sugars found in mithramycin (D-olivose, D-oliose and D-mycarose); its inactivation caused the accumulation of the nonglycosylated intermediate premithramycinone. The mtmU gene codes for a 4-ketoreductase involved in D-oliose biosynthesis, and its inactivation resulted in the accumulation of premithramycinone and premithramycin A , the first glycosylated intermediate which contains a D-olivose unit. The third gene, mtmC, is involved in D-mycarose biosynthesis and codes for a C-methyltransferase. Two mutants with lesions in the mtmC gene accumulated mithramycin intermediates lacking the D-mycarose moiety but containing D-olivose units attached to C-12a in which the 4-keto group is unreduced. This suggests that mtmC could code for a second enzyme activity, probably a D-olivose 4-ketoreductase, and that the glycosyltransferase responsible for the incorporation of D-olivose (MtmGIV) shows some degree of flexibility with respect to its sugar co-substrate, since the 4-ketoanalog is also transferred. A pathway is proposed for the biosynthesis of the three sugar moieties in mithramycin.