Effect of melanin produced by a recombinant Escherichia coli on antibacterial activity of antibiotics.

A recombinant plasmid, pYL-1, containing a tyrosinase gene whose expression is under the control of a phage T5 promoter and 2 lac operators, was constructed. Escherichia coli JM109 harboring pYL-1 was used for production of bacterial melanin. A simple procedure for the isolation and purification of melanin was developed. The ultraviolet (UV)-visible light absorption spectra of melanin prepared by chemical synthesis and derived from different organisms, including bacteria, a plant and an animal source, were determined. Melanins produced by both bacteria and chemical synthesis showed a steady increase of absorption at wavelengths of UV light ranging from approximately 200-400 nm, while melanin derived either from plant or animal sources showed an additional discrete absorption peak at wavelength 280 nm upon a similar steady increase of absorption. This additional absorption peak could be due to the presence of protein-bound melanins in animal and plant sources while a free form of melanin was obtained from bacteria and chemical synthesis. Analysis of the effect of bacterial melanin on the activity of antibiotics against E. coli revealed that the activities of polymyxin B, kanamycin, tetracycline, and ampicillin were markedly reduced in the presence of melanin, whereas the activity of norfloxacin was not affected. The reduction of the antibacterial activity may result directly from the interaction of antibiotics with melanin. However, the mechanism of this interaction remains to be demonstrated.     

Computed tomographic angiography: historical perspective and new state-of-the-art using multi detector-row helical computed tomography

Since its clinical introduction in 1991, volumetric computed tomography scanning using spiral or helical scanners has resulted in a revolution for diagnostic imaging. In addition to new applications for computed tomography, such as computed tomographic angiography and the assessment of patients with renal colic, many routine applications such as the detection of lung and liver lesions have substantially improved. Helical computed tomographic technology has improved over the past eight years with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms, but the greatest advance has been the recent introduction of multi detector-row computed tomography scanners. These scanners provide similar scan quality at a speed gain of 3-6 times greater than single detector-row computed tomography scanners. This has a profound impact on the performance of computed tomography angiography, resulting in greater anatomic coverage, lower iodinated contrast doses, and higher spatial resolution scans than single detector-row systems.     

Decrease in inner retinal thickness at para- and perifoveal areas before vascular retinopathy in patients with metabolic risk factors

BackgroundHypertension, dyslipidemia, and hyperglycemia are major risk factors for vascular retinopathy. The relationship between retinal thickness at the macular area and metabolic risk factors, as well as visual impairment, in elderly patients before developing vascular occlusion needs to be investigated.MethodsIn this prospective, case-control study, patients >60 years old, without objective visual threatened ocular diseases or systemic abnormalities, except for hypertension, dyslipidemia or/and hyperglycemia, were included for measurement of retinal thickness at the macular area by optical coherence tomography (OCT).ResultsFifty-four patients were analyzed; 11 patients had no metabolic risk factors, 16 had one, 17 had two, and 10 had three. There was no significant difference in age, and full and outer retinal thickness, but there was a significantly lower inner retinal thickness at the parafoveal (p = 0.0013) and perifoveal (p = 0.018) areas in patients with at least one metabolic risk factor. The superior (p = 0.040) and inferior (p = 0.046) inner retina at the perifovea and superior (p = 0.013) inner retinal thickness at the parafovea were sensitive to metabolic abnormalities. Only patients with three factors had significantly reduced best corrected visual acuity (BCVA).ConclusionElderly patients with metabolic risk factors had decreased inner retinal thickness at the para- and perifoveal areas before retinal vascular diseases. Accelerated inner retinal degeneration occurred prior to visual impairment.     

Serum retinoic acid levels in patients with resected benign and malignant colonic neoplasias on β‐carotene supplementation

To determine whether patients with colon cancer metabolize β‐carotene differently from benign colon polyp patients, a normal control group (n = 13) and groups of resected colon polyp patients (n = 29) or resected colon cancer patients (Dukes A and BI, n = 21) were supplemented with placebo or β‐carotene (30 mglday) taken with their morning meals for three months. Serum samples at zero and three months of the study were anlayzed blindly for retinoic acid and β‐carotene. The results showed that β‐carotene levels in the serum of colon polyp and colon cancer groups were 8‐ to 12‐fold higher than in the untreated control or the placebo‐treated groups. The benign polyp subjects (n = 17) receiving β‐carotene showed a significant rise in serum trans‐retinoic acid at three months compared with Time 0. The trans‐retinoic acid values from the colon cancer group receiving β‐carotene (n = 11) or placebo (n = 10) were significantly lower than the values from the β‐carotene‐supplemented colon polyp group. It appears that trans‐retinoic acid levels in response to β‐carotene supplementation are different between treated cancer and benign patients because of different body demands for retinoic acid.     

Reflection and critical thinking of humanistic care in medical education

The purpose of this paper is to stress the importance and learning issues of humanistic care in medical education. This article will elaborate on the following issues: (1) introduction; (2) reflection and critical thinking; (3) humanistic care; (4) core values and teaching strategies in medical education; and (5) learning of life cultivation. Focusing on a specific approach used in humanistic care, it does so for the purpose of allowing the health professional to understand and apply the concepts of humanistic value in their services.     

Usefulness of captopril renography to predict the benefits of renal artery revascularization or captopril treatment in hypertensive patients with diabetic nephropathy

This retrospective study aimed to use captopril renography (CR) for predicting the benefits of captopril treatment in hypertensive patients with diabetic nephropathy. CR was utilized in 60 hypertensive patients with diabetic nephropathy for detecting the probability of renovascular hypertension (RVH) and predicting the benefits of renal artery revascularization or captopril treatment. Ten of the 60 patients showed a high probability of RVH with marked changes of the renogram curve after an oral intake of 50-mg captopril compared to baseline findings. All of the 10 patients confirmed significant main renal artery stenosis in all of them, bilaterally in four patients and unilaterally in the remaining six patients by renal angiographic findings. After successful revascularization, blood pressure was well controlled and renal function was preserved in all of the 10 patients. The other 50 patients showed a low or intermediate probability of RVH with normal findings or unchanged on CR after 50-mg captopril. Then, captopril alone or combination treatment started and continued on 50 patients. After monitoring for at least 6 months, blood pressure was well controlled and renal function was preserved in all the 50 patients on captopril treatment. We conclude that CR should be considered as the standard diagnostic criteria of RVH and may be helpful in predicting the beneficial impact of captopril treatment in hypertensive patients with diabetic nephropathy.