Medical phototherapy in childhood skin diseases

Phototherapy is used for the medical care of cutaneous conditions that do not respond to topical or systemic medical agents, and for conditions that require broad exposure to UV as a stabilizing agent for disease. Numerous wavelengths and delivery devices of ultraviolet light are used in childhood. This article is a brief overview of the medical usage of phototherapy in childhood. In the neonatal nursery blue light (459-460 nm) is used to reduce bilirubin levels and prevent kernicterus. While psoralens and UVA (PUVA) has been demonstrated to be efficacious in a variety of pediatric skin conditions, narrowband UVB therapy (311 nm) has largely replaced psoralens and UVA as initial choice in full-body phototherapy for children. The latter is easier to deliver, with less resultant erythema than systemic psoralens and UVA which requires strict use of 24 hour protective eyewear. Narrowband UVB is therefore preferred for stabilization and clearance of a variety of inflammatory and autoimmune conditions especially atopic dermatitis, psoriasis and vitiligo. Conditions with lymphocytic infiltration, including mycosis fungoides, alopecia areata and pityriasis lichenoides can improve with Narrowband UVB as well. Alternatively, localized delivery of Narrowband UVB can be performed using the excimer laser (308 nm), which has been described for the therapy of vitiligo and alopecia areata in childhood. Some diseases with dermal infiltration including morphea and mastocytosis may do better with Psoralens and UVA or UVA1. Delivery of psoralens can also be performed topically for said conditions and in the setting of alopecia areata, thereby limiting UVA exposure, while retaining efficacy. Phototherapy can be a helpful adjunct in pediatric skin disease, but is limited by compliance issues. Parents can act as partners in the safe and effective delivery of phototherapy by standing outside the booth or inside with the child to ensure lack of movement and to aid in maintenance of eyewear. Choice of type of phototherapy and close monitoring, with parental partnership, is the key to successful treatment.

Effect of dietary plant and animal protein intake on sperm quality in monkeys

This study was conducted to evaluate the influence of animal and plant protein diets on sperm quality indices over 120 days, using the vervet monkey (Cercopithecus aethiops), as a model. These experiments were divided into a 60-day period of high-protein consumption (+/-17% crude protein), followed by a 60-day term of sustainable protein intake (+/-9% crude protein). All the diets were designed to be similar, except for the source of dietary protein that the animals consumed. High-protein diets containing milk solids or maize + legumes had no significant effect on sperm quality parameters over the first 60 days. During the next 60 days of the investigation, sustainable plant and animal protein diets had differential effects on a number of sperm quality indices. When compared to the plant-based diet, the monkeys that were given the animal protein diet containing milk solids had lower sperm counts (p < .04), reduced sperm motility (p = .04), higher sperm midpiece abnormalities (p < .05), and a trend (p = .10) towards increased sperm head defects. These findings shed some light on the impact of variable dietary proteins on sperm quality, but should be followed by longer-term investigations around this important reproductive health issue.

The influence of dietary crude protein intake on bone and mineral metabolism in sheep

Increased dietary protein consumption is thought to cause calciuresis, a negative calcium balance and increased bone loss that may result in skeletal deformities and fracture. To explore this hypothesis, 40 approximately 100-day-old meat-type Merino ram lambs were fed, for 6 months, diets with an increasing crude protein (CP) content (114, 142, 171 and 190 g/kg DM) but approximately on an iso-nutrient basis with regard to metabolisable energy, calcium and phosphorus. Increased protein consumption modestly (NS) enhanced calciuresis and resulted in significant (P < or = 0.01) limb skewness. This could not, however, be ascribed to osteopaenic bones, and compared with animals consuming lower protein rations, the bone mineral density (BMD) and vertebral trabecular bone volume of animals fed high protein diets were significantly increased: the BMD of thoracic vertebrae was positively related to the CP intake (r = 0.62; P < or = 0.001). In animals consuming higher protein diets, skeletal radiology and quantitative bone histology revealed no evidence of increased bone turnover as would be expected in animals that are in negative calcium balance. No relationship existed between limb skewness and the growth rate of lambs. However, the ratio of Ca:P in the forelimb (r = -0.98), vertebrae (r = -0.72) and rib (r = -0.42) was found to be inversely correlated with increased protein intake and resulted from an increase in the phosphorus content of bone, while the amount of bone calcium was unaffected. We conclude that qualitative micro-architectural abnormalities, and not mere bone loss, may underlie the skeletal deformities induced by increased protein consumption in sheep.

The effects of external mechanical stimulation on the healing of diaphyseal osteotomies fixed by flexible external fixation

OBJECTIVE: The purpose of this study was to investigate the effect of an externally applied mechanical stimulus on fracture healing under flexible fixation. DESIGN: Stimulation of fracture healing under various conditions of interfragmentary movement in an in vivo fracture model on 41 sheep. BACKGROUND: It is generally accepted that small interfragmentary movements (IFMs) yield better bone healing results than larger IFMs (> 1 mm). However, the optimal size of IFM within the 1-mm range remains undetermined. METHODS: Standardized transverse osteotomy of 3 mm gap size in the left ovine tibia was fixed with an unilateral external fixator. The sheep were divided into four IFM groups of 0.0, 0.2, 0.4 and 0.8 mm and stimulated with this amplitude for 1200 cycles per day at 1 Hz. After a healing period of 6 weeks, bone mineral density and biomechanical stability were evaluated to determine the quality of healing. RESULTS: The amount of callus formation increased significantly with increasing IFM (P <0.05). However, highest biomechanical stability of the healed bone and mineral density of the gap tissue was achieved with an IFM of 0.4 mm, although the differences were not significant. CONCLUSIONS: These results suggest that the optimal interfragmentary movement for acceleration of delayed fracture healing is in the range of 0.5 mm. However, the enhancement of the healing of flexibly-fixed fractures by external application of interfragmentary movement is limited. RELEVANCE: In this model the external application of a mechanical stimulus in addition to the stimulation caused by normal loading and the flexibility of the fixation did not enhance the healing process significantly. It appears that the external application of interfragmentary motion is promising perhaps only for patients unable to stimulate their fracture healing by weight-bearing.

A new high-resolution esophageal electrocardiography recording technique: an experimental approach for the detection of myocardial ischemia

Criteria for ischemic changes in the esophageal electrocardiograph (E-ECG) have not been standardized and validated. The main goal of this study was to evaluate the experimental esophageal recording of myocardial ischemia and to assess the association between ST segment alternans in the E-ECG and ischemia. Experiments were performed on 18 anesthetized sheep with occlusion of a branch of the left anterior descending artery. The bipolar signals were recorded via an esophageal lead containing three chloridized silver electrodes. Electrical signals were amplified in a self-designed, battery-supported preamplifier (gain 1000, frequency range 0.01-2000 Hz, common mode rejection 140 dB, signal noise 5-7 microV p-p), then sent to a digital oscilloscope for display and to a pulse code-modulated recorder. Surface electrocardiography (S-ECG) data were also recorded. Ischemia E-ECG revealed homogenous ST segments without any beat-to-beat alternans. Two minutes after occlusion, 14 of 15 sheep (93%) showed repetitive beat-to-beat fluctuations within the ST segment on the E-ECG. Of the 15 sheep, 7 (47%) showed ischemia in the S-ECG (P < 0.01). For calculation of the dynamic changes in the ST segment in the E-ECG, the difference in the amplitudes of the ST segment of five successive beats to the next beat, performed for 200 consecutive beats, was calculated. The central tendency of the sum of these values before versus during ischemia was 2000 mV/ms versus 5000 mV/ms (Hodges-Lehmann point estimator) (95% confidence intervals 1700/2500 versus 3350/9250 [lower limit/upper limit]). The authors have established a close temporal relationship between the magnitude of ST segment alternans recorded via E-ECG and myocardial ischemia.

IMPLICATIONS

The study presents the use of an esophageal electrocardiograph for detection of progressive changes of myocardial ischemia and infarction. During acute myocardial ischemia and infarction in sheep, the esophageal electrocardiograph has visually apparent ST alternans of amplitude in the millivolt range, in part due to a special amplifier (0.01-2000 Hz). This is therefore one very promising technique for better evaluation of electrocardiographic changes of ischemia.