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Biomedical subjects

J K Chang

Publications and source records attributed to J K Chang.

At least 127 records · Page 7Linked to original sources
PubMed1981

Morphiceptin (NH4-tyr-pro-phe-pro-COHN2): a potent and specific agonist for morphine (mu) receptors.

The synthetic peptide NH2-Tyr-Pro-Phe-Pro-CONH2 (morphiceptin), which is the amide of a fragment of the milk protein beta-casein, has morphinelike activities and is highly specific for morphine (mu) receptors but not for enkephalin (delta) receptors. It is as active as morphine in the guinea pig ileum but much less active in the mouse and rat vas deferens. The discovery of this specific morphine receptor ligand substantiates the hypothesis of multiple opiate receptors. The ligand, which may be of physiological significance since a very similar, or identical, activity can be detected in enzymatic digests of beta-casein, may prove useful for further investigation of the functions of opiate receptor subtypes.

Animals↗
PubMed1981

In vivo and in vitro release of ACTH by synthetic CRF.

The 41-residue corticotropin releasing factor (CRF) was synthesized by the solid phase method. The synthetic CRF and arginine vasopressin (AVP) were examined for ACTH releasing activity and effects on the release of 5 other pituitary hormones in vivo and in vitro. Injection of the CRF into pharmacologically blocked rats increased plasma corticosterone levels in a dose-related manner. The minimum effective dose was 1.6 x 10(-12) mol/100 g body weight. CRF also significantly stimulated release of ACTH-like immunoreactivity in a dose-related manner from rat pituitary quarters beginning at a concentration of 10(-9) M. AVP, a peptide known to have CRF activity, exhibited slightly lower corticotropin releasing activity than the CRF at equimolar dose levels. Secretion of other pituitary hormones was not appreciably altered by either the CRF or AVP.

Adrenocorticotropic Hormone↗
PubMed1981

A historical review of echocardiographic detection of pericardial effusion.

The 26 year history of echocardiographic detection of pericardial effusion ideally demonstrates the scientific method. The initial observations by Elder and Hertz in 1954 lead to animal experiments by Feigenbaum an Soulen many years later. Human applications were confirmed again and again with cardiac catheterization, surgery, autopsy and radiologic procedures. Older methods of effusion detection were compared to this new and noninvasive method and found lacking. Echocardiography has been a safe, reliable and accurate method to establish the presence of pericardial effusion in the symtomatic and asymtomatic patient. It has been used as the diagnostic standard for other detection methods. Investigators and clinicians are now utilizing echocardiography to explain cardiac physiology when pericardial effusion is present; and to follow the effects of their therapeutic interventions. While the presence of pericardial effusion has proven to be more prevalent than expected, the pathologic and hemodynamic significance of unsuspected effusion had not yet been established. Experimental and clinical studies are continuing with the aid of computerized technology for data retrieval and analysis. Thousands of patients are examined yearly with echocardiography and their statistics roll from the pages of scientific and clinical publications. The world's literature is at one's fingertips. But--the echocardiogram and its derived data are only as good as the knowledge and skill of the examiner, technologist and physician alike who " ... must understand the physics of ultrasound, the operation of a complex electronic instrument, the nature of intracardiac anatomy, and clinical cardiology as well as echographic manifestations of normal and disease conditions. Information can seldom be extracted retrospectively from the echocardiogram that was not deliberately depicted at the time of examination." More than a quarter of a century has honed present day skills to record and interpret echocardiographic tracings of pericardial effusion. Yet, it is sobering to consider how primitive our best efforts are compared to methods still unknown which will be used by technologists and physicians fifty years from now.

Echocardiography↗
PubMed1981

Possible regulatory role of dynorphin on morphine- and beta-endorphin-induced analgesia.

In previous studies, we observed that dynorphin- (1-13), but not dynorphin-(1-9), can significantly inhibit morphine- or beta-endorphin-induced analgesia despite not having any appreciable analgesic activity itself. Dynorphin-(1-13) showed no inhibitory effect on Sandoz FK33824-induced analgesia. In the present study, we examined the effect of dynorphin on morphine-, beta-endorphin-, D-ala2-D-leu5-enkephalin- or Sandoz FK33824-induced analgesia in both naive, morphine-tolerant and morphine-dependent mice. It was found that although dynorphin may inhibit morphine- or beta-endorphin-induced analgesia in naive animals, the peptide is not effective in inhibiting D-ala2-D-leu5-enkephalin- or Sandoz FK33824-induced analgesia. Dynorphin is also effective in blocking spontaneous withdrawal jumping in morphine-dependent animals. It is suggested that dynorphin-(1-13) may play a modulatory role in regulating analgesia due to morphine or beta-endorphin, but not that due to enkephalin. The action of peptides on morphine- or beta-endorphin-induced analgesia in the naive state is different from that of the tolerant state, suggesting that dynorphin may be involved in the development of morphine tolerance and physical dependence.

Analgesics↗
PubMed1981

Hypotensive action of synthetic fragments of parathyroid hormone.

Parathyroid hormone (PTH) and its N-terminal 1-34 fragment were shown to be hypotensive in dogs. In this study, synthetic bovine PTH fragments containing the N-terminal amino acids 1-34, 24-34, 24-28 and 25-27 [bPTH-(1-34), bPTH-(24-34), bPTH-(24-28) and bPTH-(24-27)] were synthesized and tested for hypotensive activity in dogs. bPTH-(1-34) is the most potent of these. The tripeptide is ineffective at doses as high as 2 mg/kg. bPTH-(24-34) and bPTH-(24-28) exhibited hypotensive activity but were less effective than bPTH-(1-34). A decrease in chain length decreased the hypotensive activity. The maximum response produced by bPTH-(1-34) was greater than that of either bPTH-(24-34) or bPTH-(24-28). The maximum responses, however, of bPTH-(24-34) and bPTH-(24-28) were similar. Another striking difference between bPTH-(1-34) and the other two effective fragments was the duration of action. Whereas the action of bPTH-(1-34) at ED50 lasted for up to 6 min the action of bPTH-(24-34) and bPTH-(24-28) lasted for less than 1 min. The hypotensive effect of these three bPTH fragments was not affected by propranolol, phentolamine, atropine, promethazine or cimetidine. In the perfused rat hindlimb, bPTH-(24-28) produced log dose-related sustained vasodilation.

Animals↗
PubMed1980

Opiate and peptide interaction: effect of enkephalins on morphine analgesia.

Interactions between the weakly analgesic enkephalins and morphine on morphine-induced analgesia were studied. Met-enkephalin exhibited morphine analgesia whereas Leu-enkephalin potentiated it. Both Met- and Leu-enkephalin, when tested alone, were not analgesic. The strongly analgesic FK33824 (Sandoz) compound, like Leu-enkephalin, also potentiated morphine analgesia. Tolerance developed to morphine analgesia but not to Met-enkephalin inhibition of morphine analgesia.

Analgesia↗
PubMed1980

Pharmacological comparison of bPTH-(1-34) and other hypotensive peptides in the dog.

The purpose of the present study was to compare the potency, effectiveness and duration of action of synthetic bPTH-(1-34) with those of other known hypotensive peptides in the anesthetized dog. Of sixteen peptides tested in the present study only 8 were demonstrated to possess hypotensive activity. While bPTh-(1-34) was one of the least potent of the hypotensive peptides, it was equal to or greater than the other peptides in terms of effectiveness and duration of action. Of all the peptides studied, substance P and eledosin were the most potent in terms of their hypotensive action. It is suggested that perhaps substance P and eledoisin might act at a different site or through different mechanisms than do vasoactive intestinal peptide (V.I.P.), corticotropin inhibiting peptide (C.I.P.), neurotensin, xenopsin, bradykinin and bPTH-(1-34).

Adrenocorticotropic Hormone↗
PubMed1979

Technique of echographic examination of right ventricular wall thickness from the right sternal border.

Right ventricular wall motion was readily accessible for echocardiographic recording along the right sternal border in 27 pediatric patients (age: 24 hrs--12 yrs). Right ventricular epicardial and endocardial wall motion could be recorded only at the right sternal border in 10 of these patients, emphasizing the need for a new, alternative examination site. Calculated measurements of right ventricular wall thickness recorded from both right and left sternal borders (7 pts) were similar (range of diff.=0--0.6 mm; mean of diff.=0.26 mm). Autopsy confirmation of right ventricular wall thickness was obtained in 2 patients. Epicardial motion could not be identified at the left sternal border in 10 patients. In these patients, right ventricular wall thickness was estimated by measuring from the inner chest wall to the endocardium. These measurements were compared to right ventricular wall thickness obtained from the right sternal border. Wall thickness obtained from the left sternal border was significantly underestimated in the absence of a definite epicardial interface (range of diff.=0.2--2.6 mm; mean of diff.=1.3 mm).

Child↗
PubMed1976

(D-Ala2)-Met-enkephalinamide: a potent, long-lasting synthetic pentapeptide analgesic.

[D-Ala2]-Met-enkephalinamide (DALA), a synthetic enkephalin analog designed by in vitro analysis, binds to opiate receptors almost as tightly as methionine-enkephalin. Since it is not susceptible to degradation by brain enzymes, low doses (5 to 10 micrograms) cause profound, long-lasting, morphine-like analgesia when microinjected into rat brain.

Analgesia↗
PubMed1976

The role of Chinese medicine in New York City's Chinatown. 1.

This study reports on use patterns of traditional Chinese and Western medical resources in New York City's Chinese community. Extensive data from field-work and interview are presented which provide significant new information concerning the health-care attitudes and problems of this unique community.

Acupuncture Therapy↗