Survey of tuberculosis drug resistance among Tibetan refugees in India.

SETTING: Tuberculosis (TB) is a major health problem among Tibetans living in exile in India. Although drug-resistant TB is considered common in clinical practice, precise data are lacking. OBJECTIVE: To determine the proportion of drug-resistant cases among new and previously treated Tibetan TB patients. DESIGN: In a drug resistance survey in five Tibetan settlements in India, culture and drug susceptibility testing (DST) for first-line drugs were performed among all consecutive new and previously treated TB cases from April 2010 to September 2011. DST against kanamycin (KM), ethionamide, para-aminosalicylic acid and ofloxacin (OFX) was performed on multidrug-resistant TB (MDR-TB) isolates. RESULTS: Of 307 patients enrolled in the study, 264 (193 new and 71 previously treated) were culture-positive and had DST available. All patients tested for the human immunodeficiency virus (n = 250) were negative. Among new TB cases, 14.5% had MDR-TB and 5.7% were isoniazid (INH) monoresistant. Among previously treated cases, 31.4% had MDR-TB and 12.7% were INH-monoresistant. Of the MDR-TB isolates, 28.6% of new and 26.1% of previously treated cases were OFX-resistant, while 7.1% of new cases and 8.7% of previously treated cases were KM-resistant. Three patients had extensively drug-resistant TB. CONCLUSIONS: MDR-TB is common in new and previously treated Tibetans in India, who also show additional complex resistance patterns. Of particular concern is the high percentage of MDR-TB strains resistant to OFX, KM or both.

Positive compared with negative margins in a single-centre retrospective study on 3957 consecutive excisions of basal cell carcinomas. Associated risk factors and preferred surgical management.

The rate of margins involvement and the associated recurrence risk in basal cell carcinomas (BCCs) varies widely in published works (7%-25% and 26%-67%, respectively). This study investigated the risk factors associated with incomplete excision and their relevance in surgical management when positive margins occur in 3957 BCCs excised in 2358 patients. This study performed a multivariate analysis on the database collected from all patients operated for BCCs in the Plastic Surgery Department between 1 January 1992 and 1 September 2007. All data collected (3957 excisions; 2358 individuals) were divided into complete and incomplete excisions groups and analyzed according to 14 variables. The overall rate of incomplete excisions was 14%. Mean age (68), size of the lesion (< 0.5 cm), BCC subtype (nodular with sclerosant aspects, sclerosant and basosquamous), location (face), infiltration depth (hypodermis and deep tissues), recurrent BCC and re-excised BCC were significantly associated with a higher rate of incomplete excision. The recurrence rate for incompletely excised tumours was 26.8%, while only 5.9% for completely excised tumours. Most of the risk factors associated to incomplete excision can be identified before surgery (by simple anamnesis and clinical examination) and successfully overcome by appropriate surgical margins. The high recurrence rate after incomplete excision and the low patient compliance towards follow-up should lead the surgeon to early re-excise residual cancer.

Adiponectin in outpatients with coronary artery disease: independent predictors and relationship with heart failure.

BACKGROUND AND AIMS: Chronic heart failure (HF) is characterised by a neurohormonal dysfunction associated with chronic inflammation. A role of metabolic derangement in the pathophysiology of HF has been recently reported. Adiponectin, an adipose-tissue-derived cytokine, seems to play an important role in cardiac dysfunction. We investigated the variation of circulating adiponectin in patients with coronary artery disease (CAD), with or without HF, in order to identify its independent predictors. METHODS AND RESULTS: A total of 107 outpatients with CAD were enrolled in the study and divided into three groups: CAD without left ventricular systolic dysfunction (group 1); CAD with left ventricular dysfunction without HF symptoms (group 2) and CAD with overt HF (group 3). Plasma adiponectin was determined by enzyme-linked immunosorbent assay. Adiponectin concentrations increased progressively from group 1 (7.6 ± 3.6 ng ml⁻¹) to group 2 (9.1 ± 6.7 ng ml⁻¹) and group 3 (13.7 ± 7.6 ng ml⁻¹), with the difference reaching statistical significance in group 3 versus 1 and 2 (p < 0.001). A multivariable model of analysis demonstrated that the best predictors of plasma adiponectin were body mass index, N-terminal pro-brain natriuretic peptide and high-density lipoprotein cholesterol. However, even after adjusting for all three independent predictors, the increase of adiponectin in group 3 still remained statistically significant (p = 0.015). CONCLUSION: Our data confirm the rise of adiponectin in overt HF. The levels of circulating adipokine seem to be mainly predicted by the metabolic profile of patients and by biohumoral indicators, rather than by clinical and echocardiographic indexes of HF severity.

Endometrial metastasis of a primitive neuroendocrine ovarian carcinoma: management and treatment of a case.

BACKGROUND: Neuroendocrine tumours are a heterogeneous group of separate clinico-pathological entities which have a common characteristic, i.e., expression of potential endocrine differentiation. In the ovary, the term "neuroendocrine" relates mainly to widely known carcinoids, but it may also be applied to rare neuroendocrine carcinomas as non-small cell type and small cell carcinomas of pulmonary type. In the literature only 11 cases of primary ovarian non-small cell neurendocrine carcinomas have been described and ten of these were associated with a surface epithelial ovarian tumour. Small cell neuroendocrine carcinoma of the ovary is a rare malignant tumour of the ovary. Advanced small cell carcinoma of the ovary is a very aggressive tumour with an overall poor prognosis and unfavourable outcome. CASE REPORT: The case reported is unique in the literature because the authors describe a rare case of endometrial metastasis of a primary ovarian non-small cell neurendocrine carcinoma without any surface epithelial ovarian tumour association. The tumour invaded up to less than half of the myometrium. The first symptoms were related to endometrial metastasis as metrorrhagia and pelvic pain while the asymptomatic presence of primary ovarian carcinoma was not acknowledged with physical examination, routine biochemistry, tumour markers, blood count and traditional transvaginal greyscale ultrasound. CONCLUSION: Magnetic resonance and three-dimensional (3D) ultrasonography with power Doppler are a great help in the diagnosis of ovarian localisation but only immunohistochemistry on histological material can provide a correct diagnosis. Immunohistochemistry expression of Ki67 is a useful marker of malignancy. Due to the rarity of this neoplasm, a general consensus for optimal treatment has yet to emerge. The reported biological aggressiveness of these tumours prompts combined treatment with radical surgery and adjuvant polychemotherapy.

Analysis of protease-activated receptor-1 and -2 in human scar formation.

Protease-activated receptor (PAR)-1 and PAR-2 are reported to contribute to the fibrotic process in a number of organs, including lung, liver, pancreas, and kidney. The aim of this study was to localize expression and biological activity of PAR-1 and PAR-2 in normal and pathological cutaneous scars. First, we investigated the immunohistochemical expression of PAR-1 and PAR-2 proteins in a series of human normal scars (NS, n = 10), hypertrophic scars (HS, n = 10), and keloids (K, n = 10). Expression of PAR-1 and PAR-2 was observed in all types of scar. Specifically, in HS and K, diffuse PAR-1 and PAR-2 positivity was found in dermal cellular areas composed of myofibroblasts, while no or minor staining was observed in the scattered fibroblasts embedded in abundant extracellular matrix in the context of the more collagenous nodules, irrespective of the type of scar. The hyperplastic epidermis overlying K was also found to be strongly PAR-1 and PAR-2 positive, whilst in most NS and HS the epidermis was faintly to moderately stained. Second, ribonuclease protection assay on paraffin-embedded specimens showed overexpression of PAR-1 and PAR-2 mRNA in K compared to NS and HS. Third, cultured human fibroblasts exposed to TGF-beta1 expressed a myofibroblast phenotype associated with overexpression of PAR-2, while PAR-1 expression was unaffected. Intracellular Ca(2+) mobilization by PAR-2 agonists in myofibroblasts was increased as compared to fibroblasts, whereas the effect of PAR-1 agonists was unchanged. Our in vivo study indicates that PAR-1 and PAR-2 are expressed in cells involved in physiological and pathological scar formation and suggests that in vitro overexpression and exaggerated functional response of PAR-2 may play a role in the function of myofibroblasts in scar evolution from a physiological repair process to a pathological tissue response.

A new approach to vulvar squamous cell carcinoma: two-year follow-up of a case report.

BACKGROUND: Vulvar carcinoma is relatively rare gynaecologic malignancy. The most prevalent vulvar cancer is squamous cell carcinoma. It is not uncommon for patients to delay seeking medical attention or for physicians to delay diagnosing the condition. This delay results in many cases being diagnosed in advanced stage. The sentinel lymph node "concept" is attractive in vulvar cancer because it has the potential to avoid a radical vulvectomy associated with uni- or bilateral inguinofemoral lymphadenectomy and, thus, to avoid the morbidity associated with formal groin dissection. CASE REPORT: A case of an 88-year-old woman with advanced local vulvar cancer is presented. A study of the inguinal-femoral lymph nodes was also conducted with intraoperative vital blue dye peritumoral injection and as the sentinel node was found to be negative for malignant metastasis, a radical vulvectomy without bilateral inguinofemoral lymphadenectomy and without additional treatment (chemotherapy and/or radiotherapy) was performed. Follow-up was performed at one, three, six, nine, 12, 18 and 24 months. No local recurrence or distant metastasis was found. CONCLUSION: The sentinel lymph node procedure allows a less aggressive treatment to be carried out in patients with invasive vulvar cancer thus reducing the complications and morbidity of treatment. Moreover, reducing the operative stress can change the overall survival and reduce the mortality linked to complications and postoperative stress.

Unusual case of cervical pregnancy after curettage for a presumptive diagnosis of intrauterine blighted ovum.

A case of cervical pregnancy after curettage for presumptive intrauterine blighted ovum is presented. The woman was successfully treated by vacuum evacuation and curettage. A 29-year-old woman, gravida 2, nulliparous, was admitted to our department at ten weeks and two days of gestation after a diagnosis of cervical pregnancy. She had been treated by curettage five days before for an initial diagnosis of intrauterine blighted ovum. Ultrasound scan examination revealed a gestational sac without foetus in the cervix four days after the first curettage. Vacuum evacuation and curettage of the cervical canal were performed and a Foley catheter was also inserted and left in place for three days. The patient was discharged in good condition on the fourth postoperative day.

[Atelectasis following cesarean section. Personal experience]. / Atelettasia secondari a taglio cesareo. Nostra esperienza.

Purpose of this paper is to evaluate the risk of ateletasis in patients that underwent surgery of the abdomen (cesarean section), since the reflex of cough in these patients is notably altered for the limitation of the diaphragmatic excursions, due to analgesic contracture. The inhibition of cough's reflex causes retention of secretions with consequent bronchial obstruction and atelectasis. Personal experience in 6 cases of atelectasis following cesarean section is reported.

Renal adaptive mechanisms in aged and hypertensive humans: possible effects of treatment.

BACKGROUND: In the aging kidney renal blood flow and glomerular filtration rate are reduced due to glomerulosclerosis. On this regard, hypertension has synergistic effects and may lead to end-stage renal disease in a significant proportion of cases. MATERIAL AND METHODS: To study the effects of antihypertensive drugs in an acute setting, we expressly designed an acute experiment to assess the renal response to mental stress (MS). In healthy elderly, the response was characterized by a prolonged and pronounced renal vasoconstriction, due to a reduction in renal autacoid modulatory capacity, particularly of prostaglandins. In older patients with isolated systolic hypertension, the response to MS was impaired, being characterized by a passive vasodilation with hyperfiltration. The effects of antihypertensive drugs were evaluated twice in adults patients with mild to moderate essential hypertension: after two weeks of pharmacological wash-out and after two weeks of treatment with the ACE-inhibitor trandolapril (4 mg), or the non-dihydropyridinic Ca2+ channel blocker verapamil (240 mg), or both (2 mg + 180 mg). RESULTS: While the three antihypertensive regimens reduced blood pressure to a similar extent, their effects on the renal response to MS were different. Each regimen re-established a renal vasoconstrictive response to adrenergic activation. However, with trandolapril, renal vasoconstriction was limited, as it occurs physiologically, to the period of blood pressure rise, while verapamil, or the combination of the two drugs, were associated with more prolonged vasoconstriction. CONCLUSIONS: Further studies are needed to confirm the nephroprotective effects of these drugs, particularly of ACE-inhibitors. These data may be a pathophysiological basis for future clinical trials.

Soluble Jagged 1 represses the function of its transmembrane form to induce the formation of the Src-dependent chord-like phenotype.

We have previously demonstrated that the expression of the soluble extracellular domain of the transmembrane ligand for Notch receptors, Jagged 1 (sJ1), in NIH 3T3 cells results in the formation of a matrix-dependent chord-like phenotype, the loss of contact inhibition of growth, and an inhibition of pro-alpha 1(I) collagen expression. In an effort to define the mechanism by which sJ1 induces this phenotype, we report that sJ1 transfectants display biochemical and cytoskeletal alterations consistent with the activation of Src. Indeed, cotransfection of sJ1 transfectants with a dominant-negative mutant of Src resulted in the loss of matrix-dependent chord formation and correlated with the restoration of type I collagen expression and contact inhibition of growth. We also report that the sJ1-mediated induction of Src activity and related phenotypes, including chord formation, may result from the inhibition of endogenous Jagged 1-mediated Notch signaling since it was not possible to detect an sJ1-dependent induction of CSL-dependent transcription in these cells. Interestingly, NIH 3T3 cells transfected with dominant-negative (but not constitutively active) mutants of either Notch 1 or Notch 2 displayed a similar Src-related phenotype as the sJ1 transfectants. These data suggest that the ability of sJ1 to mediate chord formation is Src-dependent and requires the repression of endogenous Jagged 1-mediated Notch signaling, which is tolerant to the destabilization of the actin cytoskeleton, a mediator of cell migration.

Changes in renal autacoids and hemodynamics associated with aging and isolated systolic hypertension.

The aging kidney is characterized by a decrease in renal blood flow and glomerular filtration rate mainly due to glomerulosclerosis. Nevertheless, even in the presence of these changes, the kidney maintains its functionality until advanced age. However, there is a tendency towards greater renal vasoconstriction in the elderly as compared with young individuals. This occurs either in physiological circumstances such as physical exercise, or in disease manifestations, such as the effective circulatory volume depletion that develops, for example, in heart failure. This tendency may be secondary to the reduction of renal autacoid modulatory capacity, particularly at the vasodilating prostaglandin level. In an acute experimental model we could demonstrate that, in the healthy elderly, the renal response to adrenergic activation by mental stress is characterized by a prolonged and pronounced vasoconstriction. In addition to this, in elderly patients affected by isolated systolic hypertension, we demonstrated an impairment of renal hemodynamic and humoral adaptation capacity in response to adrenergic activation and blood pressure increase. In the presence of sudden blood pressure increase, the kidney of these patients responds with a passive vasodilation and a glomerular filtration rate increase without any activation of humoral modulatory substances. The impairment in renal adaptation capacity may predispose these patients to renal injury, particularly in the presence of the many hypertensive peaks which characterize everyday life of elderly individuals. In conclusion, these results show that renal adaptation capacity of elderly patients with isolated systolic hypertension is completely lost. Further studies will elucidate whether antihypertensive treatment per se, or specific classes of antihypertensive drugs, are able to revert this impairment.

Changes in renal autacoids in aged human hypertensives.

The aging process determines several modifications of the kidney, that, however, do not provoke any dysfunction in normal conditions. But in the elderly--in the presence of stressful situations and particularly when adrenergic activation is present--the kidney is more vulnerable than in the young, and renal failure may arise. Variations typical of the aging kidney are accelerated when hypertension overlaps the physiological renal process, because both senescence and hypertension weight on the same structures, i.e. glomeruli. We studied renal hemodynamic adaptation capacity both in the healthy elderly and in patients affected by isolated systolic hypertension, in an acute experiment which requires the application of a mental stress-induced adrenergic activation. In hypertensive patients we have already demonstrated a total lack of renal adaptation capacity. In fact, while the elderly normotensives react with a prolonged and pronounced vasoconstriction, in those with isolated systolic hypertension, adrenergic activation induces a passive renal vasodilation and glomerular hyperfiltration. The anomalous adaptation capacity of renal hemodynamics is probably due to an impairment in the paracrine response of renal vasculature. Indeed in the hypertensive elderly, unlike in the normotensive one, no variations of autacoid production occur during the adrenergic activation. Following on from this, pattients affected by isolated systolic hypertension passively suffer the many hypertensive peaks which characterize their every day life. The altered renal autoregulation of the elderly with isolated systolic hypertension may explain the accelerated glomerulosclerosis and the greater incidence of renal damage and end-stage renal disease which characterize this condition. These aspects underline the primary role of the antihypertensive treatment of isolated systolic hypertension, not only for the prevention of cardiovascular mortality but also of renal damage and/or end-stage renal disease.

Impaired renal adaptation to stress in the elderly with isolated systolic hypertension.

The aim of this study was to evaluate the renal response in the elderly with isolated systolic hypertension (ISH) when an adrenergic activation, as induced by mental stress, is applied. Renal hemodynamics and kidney neurohumoral response to mental stress were studied in 8 elderly patients with ISH (aged 63 to 82 years) along with 8 elderly normotensive subjects. The study encompassed four 30-minute experimental periods (baseline, mental stress, and recovery I and II). In these patients, the mental stress-induced blood pressure rise was associated with a significant increase in both effective renal plasma flow ((131)I-labeled hippurate clearance) and glomerular filtration rate ((125)I-labeled iothalamate clearance) (+42% and +29%, respectively; P<0.01 for both), without variations in filtration fraction, while elderly normotensives reacted to adrenergic stimulation with renal vasoconstriction but with the glomerular filtration rate constant. Variations in renal vasoactive substances, which paralleled hemodynamics of the kidney, differed in the 2 groups. In normotensives, excretion (radioimmunoassay) of endothelin-1, prostaglandin E(2), and cGMP increased during the stimulus (+50%, +54%, and +59%, respectively; P<0.05). In ISH patients the release of these autacoids did not vary in any of the experimental periods. In conclusion, in patients with ISH the renal adaptive capacity to sympathetic activation is impaired, and the data may suggest that the glomerulus passively suffers the blood pressure increase, probably because of the insufficiency of the neurohumoral response, particularly in regard to the increase of endothelin-1. This hemodynamic pattern may predispose ISH patients to a higher risk of renal injury.

Successful outcome of pregnancy in a thyroidectomized-parathyroidectomized young woman affected by severe hypothyroidism.

Severe hypothyroidism was discovered in a young woman in her 29th week of pregnancy. Previously, at the age of 12 years, she had undergone thyroid surgery for Graves' disease that resulted in persistent hypothyroidism and hypoparathyroidism. After surgical excision, the patient started levothyroxine replacement therapy and had regular control of thyroid function with normal findings throughout the years. The dose of levothyroxine had not been adjusted when the pregnancy started, and at the 29th week of gestation the patient had a thyrotropin (TSH) of 72.4 microU/mL. Ultrasound studies were performed in order to monitor fetal development. The fetal parameters analyzed before the adjustment of levothyroxine therapy showed growth retardation of various degrees. All analyzed fetal parameters (biparietal diameter, cranial and abdominal circumference, humerus and femur length) improved during the last 6 weeks of gestation, showing a good correlation with the newly achieved euthyroid state of the mother. The infant was clinically euthyroid at birth and was found normal at all evaluations of the neonatal hypothyroidism screening program (1, 5, 30 days).

Excessive vasoconstriction after stress by the aging kidney: inadequate prostaglandin modulation of increased endothelin activity.

The adaptive capacity of the aging kidney to stimulation of the sympathetic nervous system, as induced by a 30-minute mental stress (MS), was assessed in 8 elderly healthy women (68 to 82 years of age) and compared with that of 8 younger women (24 to 40 years of age). The study encompassed 4 consecutive 30-minute periods (baseline, mental stress, recovery 1, and recovery 2). In the elderly subjects, baseline effective renal plasma flow (ERPF)(iodine 131-labeled hippurate clearance) was lower and glomerular filtration rate (GFR)(iodine 125-labeled iothalamate clearance) was proportionally less reduced than in the younger group; the filtration fraction (FF) was higher. The elderly group excreted more endothelin 1 (ET-1) (P < .05), prostaglandin E2 (PGE2), and 6-keto-prostaglandin F1alpha (6-keto PGF1alpha)(P < .001 for both)(radioimmunoassay). Mental stress induced similar increases in blood pressure, heart rate, and plasma catecholamines in the 2 age groups, limited to the stimulation period. In the elderly group, mental stress caused a prolonged decrease in ERPF that reached its maximum 60 minutes after mental stress (-33%, P < .05), while GFR remained constant during the whole experiment, so that FF increased. In the younger subjects, renal hemodynamic changes were limited to the mental stress period. ET-1 increased during mental stress and the first recovery period in the elderly group (+50% and +25%, P < .05) as it did in the younger group, but the elderly group differed from the younger in that vasodilating prostaglandins increased only during mental stress. In conclusion, the aging kidney reacts to adrenergic stimulation with more-pronounced and -prolonged vasoconstriction that is probably caused by a defect in prostaglandin modulation of endothelin activity. Autoregulation of GFR is maintained at the expense of increased intraglomerular pressure.

Renal adaptation to stress: a possible role of endothelin release and prostaglandin modulation in the human subject.

The aim of this study was to define the neurohumoral response associated with the renal hemodynamic perturbations induced by mental stress acting as an adrenergic stimulus. In 8 healthy women, the effects of mental stress were studied during four consecutive 30-minute periods (baseline, mental stress, recovery I, recovery II). Mental stress induced sympathetic activation as evidenced by increases in blood pressure, heart rate, and plasma norepinephrine level. Effective renal plasma flow (iodine 131-labeled hippurate clearance) decreased only during mental stress (-22%, p < 0.05 vs baseline); glomerular filtration rate (iodine 125-labeled iotalamate clearance) remained constant during the entire experiment; the filtration fraction increased significantly during mental stress and recovery I (+30% and +22%, respectively, p < 0.02 for both). Complex neuroendocrine responses were associated with the hemodynamic changes. Urinary excretion of endothelin-1 and 6-keto-PGF(1alpha) increased during mental stress (+53%, p < 0.01, and +20%, p < 0.01, respectively) and recovery I (+49% and +29%, respectively, p < 0.01 for both). Urinary cyclic guanosine monophosphate rose only during mental stress (+77%, p < 0.05), whereas excretion of PGE2 showed a stepwise increase throughout recovery I and II (+292%, p < 0.01, and +360%, p < 0.001, respectively). In conclusion, the present experiments demonstrate that renal hemodynamic response induced by mental stress is a complex reaction in which endothelin-1, prostaglandins, and presumably nitric oxide take part.

Increased renal formation of thromboxane A2 and prostaglandin F2 alpha in heart failure.

Renal formation of the vasoconstrictor prostaglandins thromboxane A2 (TXA2) and prostaglandin F2 alpha (PGF2 alpha) was investigated in 25 patients with cardiac failure, divided into New York Heart Association functional classes I to IV, and in eight healthy control subjects. Plasma renin activity (PRA) and hemodynamic parameters were also investigated. Renal vasoconstrictor eicosanoid formation, measured in urinary daily excretion, was not different between patients in class I and control subjects. Class II to IV patients showed progressively increasing production of PGF2 alpha (F = 49.8, p < 0.001, analysis of variance) and TXA2 (F = 37.8, p < 0.002). PGF2 alpha excretion peaked in class IV (+ 1266% vs class I, p < 0.001). Compared with class I, urinary excretion of thromboxane B2 was + 816% in class III and + 1561% in class IV (both p < 0.001). PRA was significantly increased only in class IV (+ 1558%, p < 0.001). The current results indicate a progressive increase in renal production of vasoconstrictor eicosanoids directly related to New York Heart Association class and suggest that these prostanoids may have a role in deterioration of renal function.

The protective impact of a covariate on competing failures with an example from a bone marrow transplantation study.

Starting from an applied Bone Marrow Transplantation (BMT) study, the problem of "unexpected protectivity" in competing risks models is introduced, which occurs when one covariate shows a protective impact not expected from a medical perspective. Current explanations found in the statistical literature suggest that unexpected protectivity might be due to the lack of independence between the competing failures. Actually, in the presence of dependence, the Kaplan-Meier curves are not interpretable. Conversely, the cumulative incidence curves remain interpretable, and therefore seem to be a candidate for solving the problem. We discuss the particular nature of dependence in a competing risks framework and illustrate how this dependence may be created via a common frailty factor. A Monte Carlo experiment is set up which accounts also for the association between the observable covariates and the frailty factor. The aim of the experiment is to understand whether and how the bias showed by the estimates could be related to the omitted frailty variable. The results show that dependence alone does not cause false protectivity, and that the cumulative incidence curves suffer the same bias as the survival curves and therefore do not seem to be a solution to false protectivity. Conversely, false protectivity may occur according to the magnitude and the sign of the dependence between the frailty factor and the covariate. The paper ends with some suggestions for empirical research.

Molecular characterization of rhizosphere and clinical isolates of Burkholderia cepacia.

Four Burkholderia cepacia strains isolated from the rhizosphere and pathological samples of infected human patients were characterized at the molecular level by different methodologies, including the determination of 16S ribosomal rDNA sequence, restriction endonuclease analysis of total DNA, random amplified polymorphic DNA fingerprinting and Southern hybridization with gene probes for nitrogen fixation and siderophore synthesis. The results indicate that the four strains cluster together within genus Burkholderia, but differ from one another. The DNA from the four strains hybridized to the nifA gene probe from Klebsiella pneumoniae, and an appreciable homology with the nifHDK structural genes of Azospirillum brasilense was demonstrated for one rhizosphere strain. Although the four isolates produced an ornibactin-like siderophore, they did not give hybridization with the pvdA probe for hydroxamate biosynthesis from Pseudomonas aeruginosa.