Protonation of Curcumin Triggers Sequential Double Cyclization in the Gas-Phase: An Electrospray Mass Spectrometry and DFT Study

ESI-protonated natural curcumin (1) undergoes gas-phase cyclization and dissociates via competitive expulsions of 2-methoxy phenol and C₄H₄O₂ (diketene or an isomer). Evidence from mechanistic mass spectrometry and from Density Functional Theory (DFT) reveals that a two-step sequential cyclization occurs for the protonated molecule prior to the unusual loss of the elements of 2-methoxy phenol. Furthermore, the presence of the methoxy group at postion-3 is essential for the second cyclization. The transformation of curcumin upon protonation in the gas phase may be predictive of its solution chemistry and explain how curcumin plays a protective role in biology.

How to use… urine dipsticks

'Urine dipstick', the commonly used point-of-care test, is an extremely sensitive investigation. Results of this test affected by numerous factors, if not meticulously linked with detailed history and examination, can lead a well-meaning clinician down the wrong clinical pathway. The aim of this article is to provide an overview of this every day test, touching on the physiological and technological basis initially, but mainly focusing on common questions like when to request the dipstick test, the correlation of dipstick results with urine specimen collected by different method and complexities of interpretation of dipstick results in everyday clinical scenarios.

Protonated N-Alkyl-2-nitroanilines Undergo Intramolecular Oxidation of the Alkyl Chain upon Collisional Activation

The collisional activation of protonated N-propyl-2-nitroaniline obtained by electrospray ionization shows two major competitive dissociation pathways: the elimination of the elements of propionic acid, [M + H - C₃H₆O₂]⁺ to give an m/z 107 ion, and of the elements of ethanol, [M + H - C₂H₆O]⁺ to give an m/z 135 ion. The mechanistic study reported here addresses these unusual fragmentations to reveal that both occur via a common intermediate formed by the transfer of an oxygen atom from the nitro group to the first carbon atom of the propyl group, allowing elimination of propionic acid and (H₂O + ethene), respectively. The corresponding loss of CH₄O does not occur when the propyl group is replaced by an ethyl group, but elimination of the elements of propanol does occur when propyl is replaced by a butyl group. Further, the product ions of m/z 107 and 135 are also formed when the propyl chain is replaced with a hexyl group.

Whistles and wheezes: don't miss diseases

Upper airway obstruction (UAO) in infants and children has a broad spectrum of presentations including benign self-resolving conditions, from mild croup, to critical life-threatening conditions which, though uncommon now, require prompt recognition and effective multidisciplinary collaborative management to achieve a good outcome. The aim of this article is to highlight the diagnostic and management difficulties in acute UAO in paediatric patients and encourage a problem-solving approach.

The role of methoxy group in the Nazarov cyclization of 1,5-bis-(2-methoxyphenyl)-1,4-pentadien-3-one in the gas phase and condensed phase

ESI-protonated 1,5-bis-(2-methoxyphenyl)-1,4-pentadien-3-one (1) undergoes a gas-phase Nazarov cyclization and dissociates via expulsions of ketene and anisole. The dissociations of the [M + D](+) ions are accompanied by limited HD scrambling that supports the proposed cyclization. Solution cyclization of 1 was effected to yield the cyclic ketone, 2,3-bis-(2-methoxyphenyl)-cyclopent-2-ene-1-one, (2) on a time scale that is significantly shorter than the time for cyclization of dibenzalacetone. The dissociation characteristics of the ESI-generated [M + H](+) ion of the synthetic cyclic ketone closely resemble those of 1, suggesting that gas-phase and solution cyclization products are the same. Additional mechanistic studies by density functional theory (DFT) methods of the gas-phase reaction reveals that the initial cyclization is followed by two sequential 1,2-aryl migrations that account for the observed structure of the cyclic product in the gas phase and solution. Furthermore, the DFT calculations show that the methoxy group serves as a catalyst for the proton migrations necessary for both cyclization and fragmentation after aryl migration. An isomer formed by moving the 2-methoxy to the 4-position requires relatively higher collision energy for the elimination of anisole, as is consistent with DFT calculations. Replacement of the 2-methoxy group with an OH shows that the cyclization followed by aryl migration and elimination of phenol occurs from the [M + H](+) ion at low energy similar to that for 1.

Regulation of protein synthesis in mammary glands of lactating dairy cows by starch and amino acids

The objective of this study was to evaluate local molecular adaptations proposed to regulate protein synthesis in the mammary glands. It was hypothesized that AA and energy-yielding substrates independently regulate AA metabolism and protein synthesis in mammary glands by a combination of systemic and local mechanisms. Six primiparous mid-lactation Holstein cows with ruminal cannulas were randomly assigned to 4 treatment sequences in a replicated incomplete 4 x 4 Latin square design experiment. Treatments were abomasal infusions of casein and starch in a 2 x 2 factorial arrangement. All animals received the same basal diet (17.6% crude protein and 6.61 MJ of net energy for lactation/kg of DM) throughout the study. Cows were restricted to 70% of ad libitum intake and abomasally infused for 36 h with water, casein (0.86 kg/d), starch (2 kg/d), or a combination (2 kg/d starch+0.86 kg/d casein) using peristaltic pumps. Milk yields and composition were assessed throughout the study. Arterial and venous plasma samples were collected every 20 min during the last 8h of infusion to assess mammary uptake. Mammary biopsy samples were collected at the end of each infusion and assessed for the phosphorylation state of selected intracellular signaling molecules that regulate protein synthesis. Animals infused with casein had increased arterial concentrations of AA, increased mammary extraction of AA from plasma, either no change or a trend for reduced mammary AA clearance rates, and no change in milk protein yield. Animals infused with starch had increased milk and milk protein yields, increased mammary plasma flow, reduced arterial concentrations of AA, and increased mammary clearance rates and net uptake of some AA. Infusions of starch increased plasma concentrations of glucose, insulin, and insulin-like growth factor-I. Starch infusions increased phosphorylation of ribosomal protein S6 and endothelial nitric oxide synthase, consistent with changes in milk protein yields and plasma flow, respectively. Phosphorylation of the mammalian target of rapamycin was increased in response to starch only when casein was also infused. Thus, cell signaling molecules involved in the regulation of protein synthesis differentially responded to these nutritional stimuli. The hypothesized independent effects of casein and starch on animal metabolism and cell signaling were not observed, presumably because of the lack of a milk protein response to infused casein.

An unusual cause of interference in a salicylate assay caused by mitochondrial acetoacetyl-CoA thiolase deficiency

Mitochondrial acetoacetyl-CoA thiolase deficiency (or beta-ketothiolase deficiency) is a rare metabolic disorder characterized by acute episodes of severe acidosis and ketosis. A case is presented of an 18-month-old boy who presented with vomiting and diarrhoea and was found to be markedly acidotic. When the acidosis persisted despite saline fluid boluses and bicarbonate correction, further investigations were undertaken. Routine biochemical investigation revealed detectable salicylate concentrations despite the parents denying its administration, which initially caused some diagnostic confusion. The results of urine organic acid analysis, however, confirmed that the diagnosis of mitochondrial acetoacetyl-CoA thiolase deficiency. The high concentrations of acetoacetate present in the patient's sample resulted in a false-positive reaction in the Trinder assay for salicylate.

A Fatal Neonatal Presentation of Medium-chain Acyl Coenzyme a Dehydrogenase Deficiency

Medium-chain acyl coenzyme A dehydrogenase (MCAD) deficiency is the most common of the inborn errors of mitochondrial fatty acid β-oxidation. A male infant was born at 39 weeks of gestation following an uneventful pregnancy. He was discharged at age 28 h after a normal first-day check, but was subsequently re-admitted and died aged 44 h. Post-mortem blood and bile spot carnitine analysis revealed a profile consistent with MCAD deficiency. MCAD genotyping revealed 985 A to G (K329E) homozygosity. This is the first confirmed case of neonatal death due to MCAD deficiency in the UK.

What is a meant when a laparoscopic surgical procedure is described as “safe”?

BACKGROUND

The literature on laparoscopic surgery contains many studies concluding that a procedure is "safe." This study aimed to review systematically articles from the past 10 years that judged a laparoscopic technique for colon resection and anastomosis to be "safe."

METHODS

The authors searched the Medline database from January 1995 to August 2005 using the search terms "laparoscopic," "colon," and "safe," selecting studies of laparoscopic colon resection or laparoscopic techniques of colonic anastomosis. They calculated exact 95% confidence intervals around estimates of the risk for death reported in the studies to determine the upper limit of the possible risk for death in a study reporting no deaths.

RESULTS

Of 135 studies matching the search criteria, 41 (30%) described operations involving laparoscopic colonic resection or anastomosis. These studies enrolled a mean number of 233 subjects. There were 26 retrospective studies, 12 prospective studies, 2 randomized control trials, and 1 case report. The estimated upper 95% confidence limits for studies reporting mortality ranged from 1.66% to 97.5%. Of the studies that reported mortality and concluded that laparoscopic colon surgery is "safe," 77.8% could not exclude a mortality rate higher than 5%.

CONCLUSION

Many studies concluding that laparoscopic colon surgery is "safe" could not exclude a high risk of operative mortality. The term "safe" is not a useful descriptor of the relative safety of laparoscopic surgical procedures, and statements about the safety of a surgical procedure should be justified with precise estimates and confidence intervals of the risk for adverse events.

A laparoscopic duodenojejunostomy for a duodenal obstruction from lymphoma

A patient with lymphoma in one-third of the duodenum causing a duodenal obstruction is described. The patient had a partial response with chemotherapy, but still was obstructed and unable to eat. He was losing weight, and chemotherapy had to be stopped. A gastrostomy tube was inserted for drainage because the stomach was quite distended. A jejunostomy tube was passed through the gastrostomy tube for feeding, but the patient did not tolerate the feeding. A laparoscopic bypass of the duodenumduodenal obstruction (from duodenum to jejunum) for this patient is shown on a video. The patient did very well after this bypass was provided. He was able to tolerate an oral diet on postoperative day 2, and on postoperative day 4, he was discharged home. He has since resumed chemotherapy, and is doing well, at this writing, 2 months after surgery. Electronic supplementary material is available for this article at http://dx.doi.org/10.1007/s00464-005-0874-2.

Acceleromyography vs. electromyography: an ipsilateral comparison of the indirectly evoked neuromuscular response to train-of-four stimulation

BACKGROUND

There is a considerable body of evidence which suggests that data obtained using acceleromyography (AMG) cannot be used interchangeably with observations obtained by mechanomyographic (MMG) or electromyograhic (EMG) methods. All previous such studies evaluated the responses from contralateral limbs. This investigation was undertaken to determine if these previously described differences were in part a function of observing the responses from opposing limbs.

METHODS

We compared the ipsilateral EMG and AMG response to an ED(95) bolus of atracurium in 50 subjects. In half of the individuals the thumb was free to move freely; in half, a small elastic preload was applied to the thumb. Train-of-four (TOF) recovery was followed until a TOF ratio >0.90 was recorded by both monitors. Acceleromyography vs. EMG differences and the resultant 95% confidence limits for twitch height (T1) and the TOF ratio were determined.

RESULTS

When the AMG TOF value had recovered to a value of 0.72 +/- 0.03; the simultaneously evoked EMG value averaged only 0.59 +/- 0.08. This difference was statistically significant (P < 0.001). Although the mean difference AMG vs. EMG was little more than 0.10, differences in an individual might be twice that amount. When the AMG TOF value had recovered to 0.90, the simultaneously evoked EMG value averaged 0.85. Again the 95% confidence limits for individual observations was very wide. With EMG, once the TOF ratio returns to a value of 0.70, T1 has returned to 95% of control. In contrast with AMG, return of T1 -95% of control requires a TOF ratio of almost 0.90. Addition of an elastic preload to the thumb decreased control TOF variability without effecting the relationship between twitch height and the TOF ratio.

CONCLUSION

Acceleromyographic TOF values tend to overestimate the extent of EMG recovery. Acceleromyographic TOF values <0.90 are indicative of incomplete neuromuscular recovery.

High fat diet increases the weight of rat ventral prostate

BACKGROUND

Understanding the mechanisms by which diet influences the prostate may eventually lead to novel approaches for preventing prostate cancer. The objective of this research is to examine the impact of dietary fat, vitamin D, and genistein on prostate weight, serum and intraprostatic androgen levels, and the expression of several androgen-response genes.

METHODS

Sprague-Dawley rats were fed, beginning at 21 days of age, for 1 or 3 months of experimental diets with high saturated fat (32.2% calories from fat), low saturated fat (3.6% calories from fat), genistein plus (20 mg/kg), genistein deficient, vitamin D surplus (4,000 U/kg), or vitamin D deficient. The body weight, food intake, the weights of the ventral prostate and dorsolateral prostate, and the levels of testosterone and dihydrotestosterone (DHT) in the serum and in the prostate were determined. The expression of androgen-response genes was characterized by Northern blot analysis.

RESULTS

The pilot experiments showed that high dietary fat appeared to consistently increase the weight of the ventral prostate, while vitamin D or genistein did not have a consistent effect on prostate weight. Further analysis confirmed that the ventral prostate is 15% (P < 0.001) heavier in the rat on a high fat diet as compared to a low fat diet. Dietary fat had no significant influence on the levels of serum and intraprostatic androgens and the expression of androgen-response genes.

CONCLUSIONS

Our results suggested that the ventral prostate weight of the rat is increased without affecting the androgen axis by feeding the animals with high fat diet beginning at 21 days of age. This observation is potentially important since epidemiological data suggest that saturated fat consumption is a major risk factor associated with prostate cancer incidence rate.

Farnesyl diphosphate synthase is abundantly expressed and regulated by androgen in rat prostatic epithelial cells

Farnesyl diphosphate synthase (FPPS) has been identified as an androgen-response gene in the rat ventral prostate using a highly sensitive PCR-based cDNA subtraction technique. FPPS is an essential enzyme that catalyzes the synthesis of farnesyl diphosphate (FPP), which is required for cholesterol biosynthesis as well as protein prenylation. We have characterized the expression of FPPS in the rat prostate in response to androgen manipulation. Northern blot analysis showed that castration induced a 10-fold down-regulation of FPPS mRNA within 24 h in the ventral prostate and androgen replacement up-regulated FPPS mRNA rapidly in the regressed ventral prostate of a castrated rat. The expression of FPPS was also regulated by androgen in the lateral and dorsal prostate, indicating that FPPS is important to androgen action in all three lobes of the prostate. Western blot analysis showed that FPPS protein level was also regulated by androgen in the prostate. Northern blot analysis of tissue specificity indicated that FPPS was most abundantly expressed in the ventral prostate of a mature rat and was responsive to androgen manipulation in the prostate and seminal vesicles, but not in other tissues. In situ hybridization study showed that FPPS mRNA was localized to the prostatic epithelium. Interestingly, the expression of FPPS was elevated in Dunning rat prostate tumor cell lines. The above findings suggest that FPPS has the potential to play an important role in androgen action and prostate cancer progression.

Androgen regulation of the largest subunit of RNA polymerase II in the rat ventral prostate

One of the dramatic changes in the prostate during androgen manipulation is the alteration in cellular content of total RNA - the amount of total RNA in each cell. The abundance of cellular total RNA correlates with the RNA polymerase (RNAP) activity in the prostate. One possible mechanism of androgen regulation of RNAP activity involves the regulation of RNAP expression. Western blot analysis showed that the largest subunit of the RNAP II, an essential component of the transcriptional machinery for mRNA, is indeed regulated by androgens. Castration down-regulates the protein level of RNAP II, whereas androgen replacement up-regulates the protein. However, androgen manipulation does not have consistent effects on the phosphorylation of the C-terminal domain (CTD) of the RNAP II. Androgen regulation of the RNAP II protein expression was also observed in the seminal vesicles but not in the thymus and liver, indicating that androgen regulation of RNAP II protein expression appears to be limited to the male sex accessory organs. These observations suggest that RNAP II plays an essential role in androgen action in male sex accessory organs.

Infantile Salmonella meningitis associated with gecko-keeping

A serotype found mainly in reptiles was isolated from cerebrospinal fluid from a 2 month old baby with meningitis. A related salmonella was isolated from gecko faeces from the floor of the tank in the baby's home, suggesting a possible source of infection, and indicating the need for hygienic precautions in homes where reptiles are kept as pets.