Application of flow cytometry for examining phytoplankton succession in two eutrophic lakes.

Flow cytometry has potential as a rapid assessment technique to evaluate phytoplankton biomass and species composition. It facilitates for multi-parameter analysis of individual cells on the basis of light scattering effects induced from cellular constituents, as well as auto-fluorescence. Fluorescence emission characteristics may be especially useful in classifying cyanobacteria as they contain phycoerythrin which emits light predominantly in the 550-600 nm waveband, chlorophyll-a (650-700 nm emission) and allophycocyanin (660 nm emission). The objective of our study was to assess the utility of flow cytometry for the rapid identification and sorting of freshwater algae and cyanobacteria species. Using a selection of laboratory-cultured freshwater algae and cyanobacteria species, this study demonstrated unique light scatter and fluorescent characteristics for each species examined, allowing for rapid species identification and sorting of mixed populations of laboratory cultures and samples from two lakes in the Rotorua region (New Zealand). Analysis of lake water samples collected over seven months demonstrated changes in abundance and community composition of phytoplankton in the two lakes and demonstrates that flow cytometry may be a useful technique for examining seasonal changes in phytoplankton composition.

The relationship between BOD:N ratio and wastewater treatability in a nitrogen-fixing wastewater treatment system.

A BOD:N:P ratio of 100:5:1 is often used as a benchmark for nutrient addition in nutrient limited wastewaters. The impact of varying nitrogen levels, whilst maintaining phosphorus constant, was studied in a simulated aerated lagoon (BOD:N of 100:0; 100:1.3; 100:1.8; 100:2.7 and 100:4.9). A synthetic wastewater was prepared using methanol, glucose and acetate as the combined carbon source, ammonium chloride as the nitrogen source and dipotassium hydrogen phosphate as the phosphorus source. Nitrogen levels did not impact organic carbon removal, but did strongly influence floc structure. With no supplemental nitrogen, growth was dispersed. Increasing the nitrogen level increased filamentous growth, with a marked change in filamentous species occurring between a BOD:N ratio of 100:1.8 and 100:2.7. Nitrogen fixation occurred at a BOD:N ratio of 100:0; 100:1.3 and 100:1.8, with nitrogen loss at BOD:N ratios of 100:2.7 and 100:4.9. At a BOD:N ratio of 100:4.9, ammonium discharge was significantly greater (1.8 mg/L) than at the lower nitrogen levels (0.04 - 0.18 mg/L). Phosphorus behaviour was more variable, however significantly more phosphorus was discharged at the lowest nitrogen level than at the highest (p<0.05). Based on readily available nitrogen, the BOD:N ratio at which nitrogen fixation no longer occurred was around 100:1.9.

The performance of a nitrogen-fixing SBR.

A laboratory study has successfully demonstrated that a nitrogen deficient thermomechanical pulping wastewater can be effectively treated in a sequencing batch reactor (SBR) operated under conditions of biological nitrogen fixation (the N-ViroTech process). In comparison to continuous stirred tank reactor activated sludge (CSTR-AS) configurations operated under either nitrogen fixing or nitrogen supplemented conditions, slightly lower removals of dissolved organic material were observed in the SBR. However, this was largely offset by significantly better suspended solids removal in the SBR, which contributes to the overall COD discharge. The settleability and dewaterability of sludge produced by the SBR was significantly better than that obtained from the nitrogen fixing CSTR-AS reactors, and comparable to that of a nitrogen supplemented system. Consistently low total and dissolved nitrogen discharges from the N-ViroTech systems demonstrated the advantage of this system over ones requiring nitrogen supplementation. The feast-famine regime of an SBR-type configuration has significant potential for the application of this technology in the treatment of nitrogen deficient waste streams, particularly those in which conventional single-stage systems may be susceptible to sludge bulking problems.

Aberrant monocyte prostaglandin synthase 2 (PGS2) expression in type 1 diabetes before and after disease onset.

METHODS: We examined monocyte prostaglandin synthase 2 (PGS2/COX2) expression in individuals at risk for or with type 1 diabetes including: (i) 58 established type 1 and 2 diabetic patients; (ii) 34 autoantibody positive (AA+) children and adults; (iii) 164 infants and young children with insulin-dependent diabetes mellitus (IDDM) susceptibility human leukocyte antigen (HLA) alleles; and (iv) 37 healthy control individuals, over a 5-yr period. RESULTS: Established type 1 diabetic patients (1 month to 30+ yr post-disease onset) had significantly higher PGS2 expression than healthy controls; by contrast, insulin-treated type 2 diabetic patients had significantly lower PGS2 expression than healthy controls. Longitudinal studies of AA+ subjects at risk for type 1 diabetes indicated that 73% (11/15) of individuals who developed this disease during the study period expressed high levels of PGS2 prior to or after onset. We also found high level PGS2 expression in genetically at-risk infants and young children that correlated with having a first-degree relative with type 1 diabetes, but not with age, gender, or HLA genotype. In this population, high level PGS2 expression coincided with or preceded autoantibody detection in 30% (3/10) of subjects. CONCLUSIONS: These findings suggest that high level monocyte PGS2 expression, although subject to fluctuation, is present in at-risk subjects at an early age and is maintained during progression to and after type 1 diabetes onset.

Breast biopsy avoidance: the value of normal mammograms and normal sonograms in the setting of a palpable lump.

PURPOSE: To review the authors' experience with patients who presented with breast lumps and had normal mammograms and normal sonograms. MATERIALS AND METHODS: The findings from 600 lumps in 486 women with no focal ultrasonographic (US) mass or mammographic finding in the area of clinical concern were retrospectively studied. Evaluated parameters included the individual reporting the lump, qualitative descriptors for the physical finding, mammographic density, US characteristics in the area of concern, whether there was a change in imaging and/or physical examination results, and whether there were diagnostic biopsy findings at follow-up. The study group included 540 lumps in 435 women who had a minimum mammographic and clinical follow-up of 2 years, as well as 60 additional lumps in 51 patients who underwent biopsy. RESULTS: No patient in the nonbiopsy group developed carcinoma at the initial site of concern during a mean mammographic and clinical follow-up period of 43 months, and all biopsy specimens were benign (negative predictive value, 100%). CONCLUSION: Results of this retrospective study suggest that breast biopsy may be avoided in women with palpable abnormalities when both US and mammography depict normal tissue at the lump site.

Identification of the sentinel node in patients with breast cancer.

Sentinel node analysis represents a significant advance in the diagnosis and treatment of invasive breast cancer. The traditional crude method of full axillary dissection for assessing the status of the axillary nodes can now be discarded in favor of the much more elegant and modern approach of minimally invasive sentinel node analysis and its attendant elimination of the morbidity of traditional axillary node dissection. The many impediments to and pitfalls in the technique of sentinel node analysis, however, must be recognized and overcome for the procedure to be reliable and consistently successful. The use of ultrasound and a smaller particle size can help overcome many of these pitfalls. Because ultrasound identification of the axillary sentinel node in patients with invasive breast cancer is possible, it may allow for percutaneous excision of these nodes in the future (Fig. 8). Combining percutaneous excision and ablation of the primary breast carcinoma with percutaneous excision of the sentinel node allows for the nonsurgical treatment of small breast cancers in the future. The modern breast radiologist should be at the forefront of these advances.

Incidental treatment of nipple discharge caused by benign intraductal papilloma through diagnostic Mammotome biopsy.

OBJECTIVE: The purpose of this study was to evaluate imaging-guided vacuum-assisted mammotome biopsy as a minimally invasive method of obtaining a satisfactory diagnosis and eliminating the bothersome symptoms in patients presenting with nipple discharge. MATERIALS AND METHODS: Forty-nine women who presented with nipple discharge and who had final pathologic diagnoses of papillary lesions were retrospectively identified. Fifty-six lesions were biopsied in this group. The examinations included mammography, ductography, sonography, and, if possible, percutaneous biopsy. All lesions were centrally located and most were superficial. Of this study group, four patients with five lesions proceeded to sonographically guided automated core biopsy, and 38 patients with 44 intraductal lesions identified by sonography advanced to sonographically guided biopsy with an 11-gauge mammotome probe. One patient underwent stereotactic 11-gauge mammotome biopsy. Patients not advancing to sonographically guided biopsy were those with masses either in the nipple or nipple-areolar complex (five patients), one patient with no identifiable lesion at sonography, and one directly referred for open surgical biopsy. RESULTS: In all biopsied patients, satisfactory tissue for diagnosis was obtained. In patients biopsied with the mammotome probe, follow-up at a mean time of 13 months revealed resolution of the presenting problematic discharge in 97.2% of patients. Complications were mild and infrequent. Only one of 50 percutaneously biopsied lesions was not benign and required subsequent surgery. CONCLUSION: Papilloma excision with percutaneous biopsy allows safe and accurate tissue analysis and a high probability of terminating the symptomatic nipple discharge.

Aberrant prostaglandin synthase 2 expression defines an antigen-presenting cell defect for insulin-dependent diabetes mellitus.

Prostaglandins (PGs) are lipid molecules that profoundly affect cellular processes including inflammation and immune response. Pathways contributing to PG output are highly regulated in antigen-presenting cells such as macrophages and monocytes, which produce large quantities of these molecules upon activation. In this report, we demonstrate aberrant constitutive expression of the normally inducible cyclooxygenase PG synthase 2 (PGS(2)/ COX-2) in nonactivated monocytes of humans with insulin-dependent diabetes mellitus (IDDM) and those with islet autoantibodies at increased risk of developing this disease. Constitutive PGS(2) appears to characterize a high risk for diabetes as it correlates with and predicts a low first-phase insulin response in autoantibody-positive subjects. Abnormal PGS(2) expression in at-risk subjects affected immune response in vitro, as the presence of a specific PGS(2) inhibitor, NS398, significantly increased IL-2 receptor alpha-chain (CD25) expression on phytohemagglutinin-stimulated T cells. The effect of PGS(2) on CD25 expression was most profound in subjects expressing both DR04 and DQbeta0302 high-risk alleles, suggesting that this cyclooxygenase interacts with diabetes-associated MHC class II antigens to limit T-cell activation. These results indicate that constitutive PGS(2) expression in monocytes defines an antigen-presenting cell defect affecting immune response, and that this expression is a novel cell-associated risk marker for IDDM.

Needle biopsy techniques.

With the ability to perform good diagnostic mammography, breast ultrasound, ductography, cyst aspiration, abscess drainage, and stereotactic or ultrasound-guided percutaneous biopsy, the modern breast radiologist should play the central role in breast diagnosis. The definitive diagnoses afforded by percutaneous breast biopsy that obviate surgery entirely in benign lesions and streamline the therapeutic surgery for malignant lesions now can be obtained routinely. The future holds even more exciting challenges for the radiologist as percutaneous lumpectomy becomes a reality. Thus the breast radiologist, armed with the technology and techniques of the twenty-first century, truly stands on the threshold of a new era.

Solid breast nodules: use of sonography to distinguish between benign and malignant lesions.

PURPOSE: To determine whether sonography could help accurately distinguish benign solid breast nodules from indeterminate or malignant nodules and whether this distinction could be definite enough to obviate biopsy. MATERIALS AND METHODS: Seven hundred fifty sonographically solid breast nodules were prospectively classified as benign, indeterminate, or malignant. Benign nodules had no malignant characteristics and had either intense homogeneous hyperechogenicity or a thin echogenic pseudocapsule with an ellipsoid shape or fewer than four gentle lobulations. Sonographic classifications were compared with biopsy results. The sensitivity, specificity, and negative and positive predictive values of the classifications were calculated. RESULTS: Benign histologic features were found in 625 (83%) lesions; malignant histologic features, in 125 (17%). Of benign lesions, 424 had been prospectively classified as benign. Two lesions classified as benign were found to be malignant at biopsy. Thus, the classification scheme had a negative predictive value of 99.5%. Of 125 malignant lesions, 123 were correctly classified as indeterminate or malignant (98.4% sensitivity). CONCLUSION: Sonography can be used to accurately classify some solid lesions as benign, allowing imaging follow-up rather than biopsy.

US-guided automated large-core breast biopsy.

To evaluate the efficacy of ultrasound (US)-guided automated large-core percutaneous needle breast biopsy, biopsy of 181 ultrasonographically suspicious breast lesions was performed by using a long-throw biopsy gun and 14-gauge needles with continuous US guidance. A "freehand" technique with either 5.0- or 7.5-MHz linear-array transducers was used. Needle core diagnoses were compared with surgical diagnoses in the 49 lesions subsequently surgically excised. The remaining 132 cases were followed for 12-36 months. Agreement between needle-core and surgical diagnoses in the 49 lesions was 100%. This group included 34 cancers (28 infiltrating ductal, two mucinous, one mixed infiltrating ductal and lobular, and one each of intraductal, infiltrating lobular, and tubular carcinoma). To date, no cancers have been found in the other 132 cases. The procedure time averaged 20 minutes, and no complications occurred. With an accuracy approaching that of excisional biopsy, US-guided needle core biopsy provides an alternative to surgery.

Infection in utero: US findings in 19 cases.

The results of antenatal sonographic studies of 19 fetuses with congenital infections were retrospectively reviewed by the authors. Recognizing the significance of these antenatal sonographic findings is important because in utero infections can have devastating effects on the developing fetus. An infectious viral agent was isolated in laboratory tests at birth in 11 patients, and the effects of a viral agent were proved clinically in eight. Antenatal sonography demonstrated abnormalities in 18 fetuses: Multiple organ systems were affected in 47%; intracranial abnormalities, cardiac abnormalities, and parenchymal calcifications occurred in 42%, 37%, and 32%, respectively; large placentas were seen in 32%; and the volume of amniotic fluid was decreased in 37% and increased in 37%. Sixty-three percent of fetuses were either aborted or died at birth; the 37% that lived were all developmentally impaired. On the basis of these sonographic, laboratory, and clinical findings, the authors conclude that when multiple organ system abnormalities are found at antenatal ultrasound, the presence of an in utero infection should be considered. The parents should be informed that there is a poor prognosis for any fetus demonstrating such abnormalities.

Tracheoesophageal fistula in utero. Twenty-two cases.

A retrospective review of 22 infants born with tracheoesophageal fistula (TEF) with in utero sonograms was performed and the literature was reviewed. TEF or esophageal atresia should be considered when there is polyhydramnios and an absent fluid-filled stomach; these findings were seen in 32% of our cases. Amniotic fluid flows freely through some TEFs, resulting in a normal amount of amniotic fluid and a fluid filled stomach (six of 22 patients), while in other cases, the fluid does not traverse the fistula easily and polyhydramnios results. Polyhydramnios was present in 62% of our cases and was the most common sonographic finding. The earliest age at which polyhydramnios was diagnosed was 24 weeks. Sonography will detect approximately one third of fetuses with TEF; an improved outcome is expected in these fetuses.

Normal fetal sacrum simulating spina bifida: "pseudodysraphism".

An erroneous diagnosis of spina bifida may be made using obstetric ultrasound (US) if the examiner is unfamiliar with normal fetal sacral anatomy or the ways in which artifacts can affect the appearance of the normal lumbosacral posterior elements. Two normal neonates who appeared to have sacral dysraphism in utero are described and compared with US and CT studies of an anatomically normal 34-week cadaver specimen. In the event of transducer angulation, lumbosacral spina bifida must be diagnosed with the utmost caution if an associated sac or mass is not present.