Regional levels of cyclic AMP in rat brain: pitfalls of microwave inactivation.

Techniques of in-vivo microwave irradiation to inactivate brain enzymes in rats were varied as to exposure configuration and output power. The rate at which metabolism was stopped was studied in various regions of the rat brain, using changes in levels of cyclic AMP and phosphodiesterase activity. Exposure times required to obtain stabilized levels of cyclic AMP varied in different brain regions, i.e., hypothalamus, cortex and cerebellum. Levels of cyclic AMP in selective regions of the brain decreased as more rapid inactivation was achieved. The authors identify important sources of variability of present microwave inactivation systems and the need for improved control of signficant microwave parameters.     

Interactions among oscillatory pathways in NF-kappa B signaling

Background  

Sustained stimulation with tumour necrosis factor alpha (TNF-alpha) induces substantial oscillations—observed at both the single cell and population levels—in the nuclear factor kappa B (NF-kappa B) system. Although the mechanism has not yet been elucidated fully, a core system has been identified consisting of a negative feedback loop involving NF-kappa B (RelA:p50 hetero-dimer) and its inhibitor I-kappa B-alpha. Many authors have suggested that this core oscillator should couple to other oscillatory pathways.     

Adsorption of ethylenediaminetetraacetic dianhydride modified oxalate decarboxylase on calcium oxalate

We used ethylenediaminetetraacetic acid dianhydride (EDTAD) to modify oxalate decarboxylase (OXDC) to improve its adsorption on calcium oxalate stones. The modified sites were identified by Ultra performance liquid chromatography-mass spectrometry (UPLC-MS) and the adsorption mechanism of the EDTAD-modified OXDC on calcium oxalate (CaOx) was investigated. We investigated adsorption time, initial enzyme concentration, temperature and solution pH on the adsorption process. Data were analyzed using kinetics, thermodynamics and isotherm adsorption models. UPLC-MS showed that EDTAD was attached to OXDC covalently and suggested that the chemical modification occurred at both the free amino of the side chain and the α-NH₂ of the peptide. The adsorption capacity of the EDTAD-OXDC on calcium oxalate was 53.37% greater than that of OXDC at the initial enzyme concentration of 5 mg/ml, pH = 7.0, at 37° C. The modified enzyme (EDTAD-OXDC) demonstrated improved oxalate degradation activity at pH 4.5?6.0. Kinetic data fitting analysis suggested a pseudo second order kinetic model. Estimates of the thermodynamic parameters including ΔG⁰, ΔH⁰ and ΔS⁰ of the adsorption process showed it to be feasible, spontaneous and endothermic. Isotherm data fitting analysis indicated that the adsorption process is reduced to monolayer adsorption at a low enzyme concentration and to multilayer adsorption at a high enzyme concentration. It may be possible to apply OXDC to degradation of calcium oxalate stones.     

Mitochondrial DNA structure and colony expansion dynamics of New Zealand fur seals (Arctocephalus forsteri) around Banks Peninsula

New Zealand fur seals are one of many pinniped species that survived the commercial sealing of the eighteenth and nineteenth centuries in dangerously low numbers. After the enforcement of a series of protection measures in the early twentieth century, New Zealand fur seals began to recover from the brink of extinction. We examined the New Zealand fur seal populations of Banks Peninsula, South Island, New Zealand using the mitochondrial DNA control region. We identified a panmictic population structure around Banks Peninsula. The most abundant haplotype in the area showed a slight significant aggregated structure. The Horseshoe Bay colony showed the least number of shared haplotypes with other colonies, suggesting a different origin of re-colonisation of this specific colony. The effective population size of the New Zealand fur seal population at Banks Peninsula was estimated at approximately 2500 individuals. The exponential population growth rate parameter for the area was 35, which corresponds to an expanding population. In general, samples from adjacent colonies shared 4.4 haplotypes while samples collected from colonies separated by between five and eight bays shared 1.9 haplotypes. The genetic data support the spill-over dynamics of colony expansion already suggested for this species. Approximate Bayesian computations analysis suggests re-colonisation of the area from two main clades identified across New Zealand with a most likely admixture coefficient of 0.41 to form the Banks Peninsula population. Approximate Bayesian computations analysis estimated a founder population size of approximately 372 breeding individuals for the area, which then rapidly increased in size with successive waves of external recruitment. The population of fur seals in the area is probably in the late phase of maturity in the colony expansion dynamic.     

Teaching cases: Pulmonary lymphangitic carcinomatosis as a primary manifestation of colon cancer in a young adult

Abstract: Pulmonary lymphangitic carcinomatosis is a metastatic lung disease characterized by diffuse spread of the tumour to the pulmonary lymphatic system. We describe the case of a 31-year-old woman who initially received a diagnosis of sarcoidosis based on the results of imaging studies. However, results of a transbronchial biopsy led to the diagnosis of pulmonary lymphangitic carcinomatosis from metastatic colon cancer.The case: A 31-year-old woman presented to her primary care provider with a nonproductive cough and shortness of breath, which she had experienced intermittently for 1 month. She had no fever, chills or night sweats. She had type 1 diabetes mellitus and hypertension. The patient had experienced multiple miscarriages and was 1 month post partum. She had a 10-pack-year history of smoking. Her father and maternal grandfather both had colon cancer, which, in her father, had been diagnosed after his death at the age of 45. The patient received a diagnosis of exacerbated chronic obstructive pulmonary disease, which was treated with a short course of corticosteroids and broad-spectrum antibiotics. Her condition did not improve.Two months later, the patient presented to the emergency department with dyspnea. A radiograph of her chest showed interstitial lung disease, thickening of the right paratracheal region and hilar prominence. A computed tomography (CT) scan of her chest revealed extensive paratracheal, subcarinal and para-aortic lymphadenopathy. It also showed diffuse consolidation with a nodular pattern throughout the lungs, particularly in the upper lobes and the lower left lobe. She received a diagnosis of sarcoidosis, which her primary care physician treated with corticosteroids. Her symptoms abated, but less than 1 week later, her condition worsened. Oxygen therapy was started at home.A respirologist saw the patient 6 months after the onset of her symptoms. She still had exertional dyspnea and a nonproductive cough without hemoptysis. She had lost 20 pounds in the 5 months preceding the visit. She had tachypnea and tachycardia, and was normotensive and afebrile. She did not have enlarged lymph nodes, skin changes or peripheral edema.Examinations of the patient''s abdomen and heart sounds were unremarkable. We heard rhonchi and crackles in the base of both lungs. A radiograph of her chest showed diffuse interstitial and septal thickening in both lungs (Figure 1). A CT scan showed large nodular areas, ground-glass opacities and thickened interlobular septa with interstitial lung disease (Figure 2).Open in a separate windowFigure 1: Chest radiograph of a 31-year-old woman showing diffuse interstitial and septal thickening (arrow) in both lungs.Open in a separate windowFigure 2: Computed tomography scan showing nodular thickening of interlobular septa (white arrow), seen as polygonal arcades with thickened and nodular limbs, and ground-glass opacities (black arrows).Results of a transbronchial biopsy showed a moderate to poorly differentiated adenocarcinoma. Immunohistochemical studies of the biopsy specimen showed a pattern of staining consistent with metastatic adenocarcinoma most suggestive of a primary origin in the colon. A colonoscopy showed a mass in her proximal sigmoid colon, and biopsy results confirmed the mass to be a moderately differentiated adenocarcinoma. A bone scan showed multiple tomours in her thorax and lumbar spine.The patient was admitted to hospital for chemotherapy (FOLFOX4, a regimen of oxaliplatin, leucovorin and 5-fluorouracil). She was transferred the next day to the intensive care unit because of worsening respiratory distress, necessitating mechanical ventilation. The chemotherapy was continued; however, the patient died of respiratory failure 11 days after admission to hospital.Pulmonary lymphangitic carcinomatosis occurs in 6%–8% of patients with pulmonary metastases.¹ The spread of tumour cells to the pulmonary lymphatic system or the adjacent interstitial tissue results in thickening of the bronchovascular bundles and septa. Desmoplastic reaction due to proliferation of neoplastic cells, and lymphatic dilation by edema fluid or tumour secretions contribute to this interstitial thickening. Spread of the neoplasm outside the interstitium and lymphatic spaces into the adjacent parenchyma can result in a nodular pattern.² Although virtually any metastatic neoplasm can cause pulmonary lymphangitic carcinomatosis, the common locations of the primary tumour are the breasts, stomach, lungs, pancreas and prostate^1,3 (Open in a separate windowPatients with pulmonary lymphangitic carcinomatosis often present with breathlessness and a nonproductive cough. As with our patient, the onset of pulmonary symptoms may precede diagnosis of the primary tumour; however, the frequency of this presentation is unknown. Although chest radiographs appear normal for 30%–50% of patients with histologically proven disease,² pulmonary lymphangitic carcinomatosis has several characteristic changes that can be observed on radiographs (Box 1). Transbronchial biopsy is required for a definitive diagnosis.Open in a separate windowBox 1Pulmonary lymphangitic carcinomatosis can mimic sarcoidosis radiologically. Nodular thickening and ground-glass attenuation are seen in 30%–60% of patients with sarcoidosis. The nodules in sarcoidosis mainly involve central regions of the middle and upper lobes of the lungs. In contrast, changes usually occur in the lower lobes in pulmonary lymphangitic carcinomatosis. Although imaging studies may suggest sarcoidosis, the diagnosis should be confirmed by biopsy results indicating noncaseating granulomas and by the exclusion of other causes of granulomatous disease. Rapid onset and progression of symptoms, asymmetrically enlarged lymph nodes, predominant disease in the lower lobes of the lungs and lack of response to steroids within 2–4 weeks also should alert clinicians to a diagnosis other than sarcoidosis. Thickening of the interlobular septa and peribronchovascular interstitium without a nodular pattern may be seen in other conditions, such as pulmonary edema and idiopathic pulmonary fibrosis.²Although the diagnosis was delayed for our patient, an earlier diagnosis may not have altered the outcome because of the condition''s extremely poor prognosis in most cases. Less than half of patients with pulmonary lymphangitic carcinomatosis who present with respiratory symptoms survive for 3 months.¹ However, platinum-based chemotherapy has led to transient remissions in some cases.⁴Although our patient did not undergo genetic testing, her young age at presentation and strong family history of colon cancer led to a diagnosis of hereditary nonpolyposis colorectal cancer. This condition accounts for 2%–3% of colorectal cancers and is the most common form of hereditary colorectal cancer.⁵ It is characterized by an early onset, with an average age at diagnosis of about 45 years and the presence of tumours predominantly on the right side of the colon. Patients with this condition are also at increased risk of having more than 1 primary colorectal tumour at the time of diagnosis (synchronous neoplasms) and of having another primary tumour after successful treatment of the index tumour (metachronous carcinoma). Patients with this condition are more likely than others of the same age and sex to experience tumours of the endometrium, small bowel, stomach, renal pelvis ureter and ovaries. Skin lesions, including carcinomas and nonmalignant lesions such as sebaceous adenomas and keratoacanthomas, are also more common among these patients.⁶Our patient had unusual features of pulmonary lymphangitic carcinomatosis, including involvement of the sigmoid colon and metastatis to the lungs and spine without liver involvement. This presentation is seen in only about 9% of rectal cancers.⁷ If hereditary nonpolyposis colorectal cancer is suspected, a biopsy of the tumour and genetic testing should be carried out to identify mutations. Once identified, relatives at high risk for colorectal cancer should be counselled and screened for these mutations. Those who carry the mutations should have a colonoscopy every 2 years starting at age 20–25.⁶Anish Thomas MD Robert Lenox MD Department of Medicine State University of New York Syracuse, New York     

Functional mapping of an oligomeric autotransporter adhesin of Aggregatibacter actinomycetemcomitans

Extracellular matrix protein adhesin A (EmaA) is a 202-kDa nonfimbrial adhesin, which mediates the adhesion of the oral pathogen Aggregatibacter actinomycetemcomitans to collagen. EmaA oligomers form surface antenna-like protrusions consisting of a long helical rod with an ellipsoidal ending. The functional analysis of in-frame emaA deletion mutants has located the collagen binding activity to the amino terminus of the protein corresponding to amino acids 70 to 386. The level of collagen binding of this deletion mutant was comparable to the emaA mutant strain. Transmission electron microscopy studies indicate that the first 330 amino acids of the mature protein form the ellipsoidal ending of the EmaA protrusions, where the activity resides. Amino acid substitution analysis within this sequence has identified a critical amino acid, which is essential for the formation of the ellipsoidal ending and for collagen binding activity.