An inexpensive ex-vivo porcine laparoscopic Nissen fundoplication training model.

BACKGROUND: We recently implemented the use of an ex-vivo porcine model to teach residents the fundamentals of performing a laparoscopic Nissen fundoplication. METHODS: Residents were trained using intact porcine esophagus, stomach, and spleen placed in a standard video-trainer. They were later asked to complete a survey containing a course evaluation. RESULTS: Sixteen residents (R1-R4) completed the survey. They agreed that (1) the exercise was a valuable use of their limited time, (2) repeating the exercise will be of additional benefit, (3) it will improve their ability to perform or assist in an actual case in the OR, and (4) the surgical principles learned using the model will transfer to other laparoscopic cases. Significant subjective improvements were reported in resident comfort level in assisting in or performing a laparoscopic Nissen fundoplication. CONCLUSIONS: The use of an inexpensive ex-vivo porcine training model increases resident comfort level in performing a Nissen fundoplication in the operating room.     

Response of joint capsule neurons to axial stress and strain during dynamic loading in cat

1. Experiments were conducted to test the hypothesis that the responses of joint capsule mechanoreceptors better encode tissue stress or tissue strain. The experimental model was a small ligament from the cat knee capsule, which was stretched uniaxially in vitro. Experiments were done with either force or displacement as the controlled variable, and with steps, sinusoids, or pseudorandom Gaussian noise (PGN) as the input function. 2. The strength of coupling between neural discharge and both strain and stress was quantified during step experiments using linear correlation coefficients. The correlation between the frequency of neural discharge and stress was 0.93 +/- 0.09 (SD). The correlation between frequency of neural discharge and strain was -0.91 +/- 0.06. The magnitudes of these correlation coefficients were not significantly different. 3. The strength of coupling between neural discharge and both strain and stress during sinusoidal and PGN experiments was quantified by the use of an information theoretic statistic, transinformation. Out of 282 sinusoidal runs, transinformation between neural discharge and stress was significantly greater than transinformation between strain and neural discharge 241 times. Transinformation between strain and neural discharge was significantly greater 15 times. 4. During PGN experiments, transinformation between stress and neural discharge was greater than transinformation between strain and neural discharge in all 19 experimental runs. 5. Conditional transinformation between strain and neural discharge, given stress, was calculated for all sinusoidal and pseudorandom experiments. This statistic was greater than zero in 268 out of 289 experimental runs, indicating that a component of strain independent of stress is being signaled in the neural discharge.     

A treadmill test of sprint running

Anaerobic power is characterized by a high degree of specificity regarding both the recruited muscles as well as the recruitment pattern. The popular Wingate Anaerobic Test (WAnT) is a cycling test that does not satisfy the need for a running-specific anaerobic test. We describe such a test, using a novel type of a commercially available treadmill (BRL 1800, Gymrol, France). The ergometer is equipped with a torque motor to neutralize the frictional resistance of the treadmill belt, and a hip-belt harness connected to a horizontal rod. Force applied to the harness is monitored by a strain gauge mounted on the rod, while vertical movement is monitored by a potentiometer at the posterior fixed end of the rod. These, in conjunction with the treadmill belt speed, enable the computation of horizontal and vertical power as well as the combined total output. Power is calculated both as 'peak' power (highest 2.5 s segment) and 'mean' power (20 s duration). Preliminary results of young athletes were generally consistent with the expected age-related changes in anaerobic power. Values obtained on the anaerobic treadmill were always higher than the corresponding WAnT values previously obtained in comparable age groups. The higher values were probably due to the larger muscle mass involved and the shorter peak and mean power durations (2.5 and 20 s versus 5 and 30 s in the WAnT, respectively). This test should enable not only running-specific anaerobic power monitoring but also the characterization of the relationship between the horizontal and vertical components of that power.     

Adult daughters and parent care: a comparison of one-, two- and three-generation households.

This paper compares the effects of parent-care associated with three living arrangements of elderly widowed mothers who were being helped by married daughters: elderly mother living separately; two-generation households (mothers, daughters, sons-in-law); and three-generation households (grandchildren present). Daughters whose mothers lived separately fared the best; their mothers were the most cognitively and functionally capable and the daughters reported the fewest negative effects of caregiving. Daughters in two-generation households provided the most care; their mothers were the oldest and most impaired. Since daughters in three-generation households reported more negative mental and emotional effects of care, the unique problems of caregiving in such households are discussed.     

Metronidazole susceptibility testing for Helicobacter pylori: comparison of disk, broth, and agar dilution methods and their clinical relevance.

Since the methods for metronidazole susceptibility testing of Helicobacter pylori have not been standardized or validated, we compared three methods that are used to test the metronidazole susceptibilities of 25 isolates of H. pylori. Specifically, we examined the methods of Steer's replicator agar dilution, tube broth microdilution, and modified Kirby-Bauer disk diffusion. The metronidazole disk zone sizes obtained by the disk diffusion method correlated well (r = 0.74) with the MICs obtained by the agar dilution method. Afterward, the disk diffusion method was used to characterize the metronidazole susceptibilities of 44 isolates of H. pylori. Dual therapy (bismuth and metronidazole) proved to be highly effective against metronidazole-susceptible strains (81.6% eradication rate) but fared poorly against resistant strains (16.7% eradication rate; P < 0.01). Using agar dilution testing, we validated the modified Kirby-Bauer disk diffusion method for metronidazole susceptibility testing of H. pylori and conclude that it is practical, accurate, and clinically applicable.     

Growth hormone therapy in the elderly: implications for the aging brain.

Growth hormone (GH) secretion declines during normal aging, resulting in lower serum insulin-like growth factor (IGF)-I levels. It has been proposed that many of the catabolic changes seen in normal aging, including osteoporosis and muscle atrophy, are in part caused by the decreased action of the GH-IGF-I axis. In addition, patients with GH deficiency have increased overall cardiovascular mortality. Several investigators have initiated GH treatment for elderly patients with relative hyposomatotropinemia. Initial reports suggest that GH can increase muscle mass, improve exercise tolerance, increase REM sleep and cause an enhanced sense of well-being. The basis for neuropsychiatric changes during GH therapy may be due to a direct CNS action of GH itself, to the increased IGF-I secretion which GH elicits, or to enhanced functioning of peripheral organ systems. Long-term studies will determine whether GH or IGF-I can exert a neurotrophic action in the aging brain.     

The isoproterenol-induced chloride current and cardiac resting potential.

Isoproterenol can induce potentially arrhymthogenic depolarizations of the resting membrane of single guinea-pig ventricular myocytes. This effect on resting potential of single guinea-pig ventricular myocytes differs qualitatively from results obtained by others from intact cardiac muscle preparations and also differs from our experience with single dog ventricular myocytes. We performed experiments on dog and guinea-pig ventricular myocytes in an attempt to clarify the effects of isoproterenol on the resting potential of mammalian ventricular myocytes. Voltage recordings with 40-60 M omega 3 M potassium chloride filled microelectrodes revealed an isoproterenol-induced depolarization of 4.3 +/- 1.0 mV in guinea-pig but no depolarization in dog myocytes. Activation of an outwardly rectifying chloride current is responsible for the isoproterenol-induced depolarization of guinea-pig ventricular myocytes. Our whole cell patch clamp recordings consistently revealed such a current in guinea-pig cells but always failed to demonstrate an isoproterenol-induced chloride current in dog myocytes under identical conditions. In contrast to single cells, isoproterenol did not depolarize intact guinea-pig papillary muscle when potential was recorded with 40-60 M omega 3 M KCl filled electrodes. Furthermore, we saw no depolarization in single guinea-pig myocytes when recording electrodes did not contain chloride. We conclude that: (1) despite activation of a chloride current, isoproterenol does not significantly depolarize guinea-pig ventricular muscle unless the driving force for the current at the resting potential is increased by elevating [Cl]i above physiological levels, and (2) an isoproterenol-induced chloride current, although demonstrable in guinea-pig ventricular cells, is not present in healthy dog ventricular cells.