High yielding synthesis of 2,2'-bipyridine macrocycles, versatile intermediates in the synthesis of rotaxanes

We present an operationally simple approach to 2,2'-bipyridine macrocycles. Our method uses simple starting materials to produce these previously hard to access rotaxane precursors in remarkable yields (typically >65%) across a range of scales (0.1-5 mmol). All of the macrocycles reported are efficiently converted (>90%) to rotaxanes under AT-CuAAC conditions. With the requisite macrocycles finally available in sufficient quantities, we further demonstrate their long term utility through the first gram-scale synthesis of an AT-CuAAC [2]rotaxane and extend this powerful methodology to produce novel Sauvage-type molecular shuttles.

Correction: High yielding synthesis of 2,2′-bipyridine macrocycles, versatile intermediates in the synthesis of rotaxanes

Correction for ‘High yielding synthesis of 2,2′-bipyridine macrocycles, versatile intermediates in the synthesis of rotaxanes’ by J. E. M. Lewis et al., Chem. Sci., 2016, DOI: 10.1039/c6sc00011h.

Zinc levels and infections in hospitalized patients with AIDS

Impaired cellular and humoral immunity and phagocytic function have been attributed to zinc deficiency. This study examined the association between low serum zinc concentration and opportunistic infections in hospitalized patients with the acquired immune deficiency syndrome (AIDS). We examined the records from all 505 inpatient consultations performed by our Nutrition Service from May 1992 through June 1994. The medical records from all 228 patients with AIDS with known serum zinc levels (determined by atomic absorption spectrophotometry) were reviewed. The length of HIV seropositivity, most recent CD4 count, presence of diarrhea, and degree of malnutrition were noted. The principal diagnosis accounting for the admission was grouped according to the type of infection: Pneumocystis carinii pneumonia (PCP), viral, fungal, bacterial, and other. Sixty-seven patients (29%) had abnormally low serum zinc levels (LSZ < 55 micrograms/dL), 49 patients (21%) had borderline low serum zinc (BSZ > or = 55 and < or = 65 microgram/dL), and 112 (49%) patients had normal serum zinc levels (NSZ > 65 micrograms/dL). There was no significant difference among the groups in CD4 count, length of HIV seropositivity, presence of diarrhea, or severity of malnutrition. Patients with zinc deficiency (LSZ) had a significantly higher incidence of bacterial infection than did patients with normal zinc. Patients with borderline zinc levels had an intermediate incidence of bacterial infection. There were no significant differences among the three groups in the incidence of PCP, viral, or fungal infections. Severe zinc deficiency was noted in 29% and borderline levels in an additional 21% of hospitalized AIDS patients. A low zinc level was not associated with the length of HIV seropositivity, CD4 count, or degree of malnutrition. Hypozincemia was associated with an increased incidence of concomitant systemic bacterial infections.

Serum zinc and protein levels: lack of a correlation in hospitalized patients with AIDS

Abnormally low serum zinc levels are associated with advanced states of malnutrition. Zinc levels are thought to parallel serum albumin, and repletion of zinc has reportedly led to increased albumin. We examined the correlation between zinc deficiency and serum proteins in hospitalized patients with AIDS. Over 500 inpatient consultations were performed by our Gastroenterology-Nutrition Consult Service from May 1992 to June 1994. We reviewed the medical records from all 228 AIDS patients in whom a serum zinc level was measured (by atomic absorption spectrophotometry). The correlation between serum zinc, albumin, prealbumin, and transferrin drawn on the same hospital day was analyzed by linear regression. The patients were stratified by the level of albumin, group A albumin < 2.0 g/dL, group B albumin 2.0-2.9 g/dL, and group C albumin > 3.0 g/dL, to allow comparison of the incidence of diarrhea and mean zinc level by chi square. Thirty-four patients had more than one serum zinc and albumin determination; the change over time was compared by linear regression. Serum zinc and albumin, prealbumin, and transferrin levels did not correlate strongly (r2 < or = 0.01). Furthermore, changes in zinc over time did not correlate with parallel changes in serum albumin (r2 < or = 0.01). In patients grouped by albumin, the proportion of patients with diarrhea did not differ significantly. The mean zinc levels were also not statistically significantly different. Serum zinc levels do not strongly correlate with serum proteins in hospitalized patients with AIDS. Serial measures of zinc over time also do not correlate strongly with changes in albumin. The incidence of diarrhea was not significantly different in patients with hypoalbuminemia or hypozincemia when compared with patients with near normal albumin or zinc. The relationship between zinc and serum proteins in AIDS patients is not linear. Zinc deficiency should be assessed in patients independent of the serum albumin.

Steatorrhea: a common manifestation in patients with HIV/AIDS

Multiple infectious causes of diarrhea are known in patients with HIV/AIDS. Maldigestion and malabsorption have been reported in patients with HIV/AIDS and may be independent of infectious etiologies. Among ambulatory patients with HIV/AIDS, we examined the prevalence of fat malabsorption (steatorrhea). Sixty-one patients with unexplained diarrhea (defined as > 2 stools/d) and/or weight loss despite adequate caloric intake (and without clinical evidence of chronic pancreatitis) were evaluated in our outpatient Gastroenterology-Nutrition Clinic between March 1, 1993, and July 1994. Patients were instructed by a dietitian to follow a > or = 100 g/d fat diet for 24 h before submitting a stool sample for qualitative (or quantitative) fecal fat determination. Forty-five patients, 32 with ongoing diarrhea and 13 without diarrhea, submitted stool samples. Twenty-two of 45 patients (49%) had qualitative or quantitative steatorrhea, 16/32 with diarrhea (50%) and 6/13 patients without diarrhea (46%). Thirty of 32 patients with diarrhea had had extensive microbiologic and/or endoscopic evaluations. Only 9 patients had a detectable intestinal pathogen, 5 patients had cytomegalovirus (4 treated), 4 patients had cryptosporidia (3 treated), and 1 patient had microsporidia. Steatorrhea, as determined by abnormal qualitative fecal fat, is detectable in nearly 50% of patients with HIV/AIDS. Fat malabsorption appears to be a primary defect in these patients independent of detectable pathogens. Assessment of fat malabsorption should be considered in patients with unexplained weight loss or diarrhea before extensive evaluation for opportunistic infections.

Using the patient's history to estimate the probability of coronary artery disease: a comparison of primary care and referral practices

PURPOSE

According to probability theory, the interpretation of new information should depend on the prior probability of disease. We asked if this principle applies to interpreting the history in patients with chest pain. We compared the prevalence of coronary artery disease (CAD) in patients who had similar histories but who came from populations with different disease prevalence.

PATIENTS AND METHODS

We studied two high-disease-prevalence populations (patients referred for coronary arteriography) and two low-disease-prevalence populations (patients from primary care practices). We used clinical characteristics of one arteriography population to develop a logistic rule for estimating the probability of coronary artery narrowing. The number of clinical findings determined the logistic score, which was proportional to the prevalence of CAD.

RESULTS

The prevalence of CAD was much lower in the primary care population than in the arteriography population, even when patients with similar logistic scores, and thus similar clinical histories, were compared.

CONCLUSION

A clinician must take account of the overall prevalence of disease in the clinical setting when using the patient's history to estimate the probability of disease. Failure to observe this caution may lead to errors in test selection and interpretation.

Diuresis in the ascitic patient: a randomized controlled trial of three regimens

To compare the efficacy of three commonly used diuretic regimens in the treatment of ascites, we randomized 90 patients to three treatment groups: Sequential Spironolactone (spironolactone followed by furosemide if necessary), Combination (spironolactone and furosemide in combination), and Furosemide (furosemide given alone). Diuretics were begun at a low dose by mouth and the dosage increased until a 0.4-0.8 kg daily diuresis was achieved. The clinical and laboratory findings were comparable for the three experimental groups on admission to the study. All three regimens achieved a comparable rate of diuresis. To do so was far more difficult with furosemide alone, which required repetitious upward adjustments in dosage and massive KCl supplements. The incidence of encephalopathy, hepatorenal syndrome, and marked electrolyte abnormalities was similar for the three treatment groups except that severe hyperkalemia was more frequent on combination therapy. We conclude that diuresis should be initiated with one of the two spironolactone regimens and not with furosemide as the sole agent.

Enhanced bioavailability and decreased clearance of analgesics in patients with cirrhosis

The effect of moderate cirrhosis on the bioavailability and systemic clearance of three model analgesic compounds (pethidine, pentazocine, and salicylamide) with substantial first-pass metabolism was examined in 8 cirrhotic subjects and 4 agematched healthy controls. There was a 46% decrease in the clearance of pentazocine and a 278% increase in bioavailability. The corresponding figures for pethidine were 36% and 81%. The area under the plasma curve after oral salicylamide was increased by 551% in cirrhotic subjects compared with controls. This study demonstrated that drugs with the highest hepatic clearance will have the largest relative increases in bioavailability in cirrhotic patients due to portosystemic shunting. The decrease in clearance and increase in bioavailability will have multiplicative, rather than simply additive, effects on total area under the curve and, if related, pharmacologic response.