Possible prediction of myeloid and lymphoid crises in chronic myelocytic leukemia at onset by determining the methylation status of the major breakpoint cluster region

To investigate the relationship between the pattern of methylation at the major breakpoint cluster region (M-BCR) and transformation of chronic myelocytic leukemia (CML) from the chronic to the blastic phase, the M-BCR methylation status was examined serially from chronic to blastic phase in 23 CML patients. The DNA of mononuclear cells from bone marrow or peripheral blood was digested with restriction enzymes HpaII and BglII, and hybridized with a 5'M-BCR probe. The methylation status was stable during evolution of CML from chronic to the myeloid blastic phase. Cells in both phases showed consistent methylation patterns consisting of fully methylated rearranged fragments of variable size, 4.8, 3.1/3.0, and 2.7/2.5 kb. Conversely, there was substantial heterogeneity in methylation patterns in patients with lymphoid crisis. All lymphoid-crisis patients studied in blastic phase showed a pattern distinct from that of the chronic phase in the same patient, as well as from the myeloid pattern, suggesting cell lineage-specific M-BCR methylation. Moreover, in four of six patients with lymphoid crisis, the chronic-phase patterns were different from those of cases with myeloid crisis. Ph-positive and -negative acute lymphocytic leukemia (ALL) showed methylation patterns different from those of lymphoid crisis in CML. Although the number of patients with lymphoid crisis studied has been limited, these results suggest that analysis of M-BCR methylation status may be of clinical use in distinguishing lymphoid from myeloid crises and predicting the cell lineage of a crisis when the disease is still in the chronic phase.

Effects of M1 and M2 receptor agonists and blockers on dog respiration

AIM

To study the effects of M1 and M2 receptor agonists and blockers on dog respiration.

METHODS

Using thoracic respiratory transducer and RM-86 multipurpose polygraph to determine respiratory rate (RR), tidal volume (TV), and minute ventilation volume (MVV), and DH-100G blood gas analysis instrument to analyze pO2, pCO2 and pH.

RESULTS

Pilocarpine (Pil, an M1-R subtype agonist) 0.5, 1, and 2 mg.kg-1 iv caused increases in RR, MVV, and pO2, and a decrease in pCO2. The excitatory effects of Pil were antagonized by pretreatment with pirenzepine (Pir, 3 mg.kg-1, iv) and scopolamine (Sco, 2 mg.kg-1, iv). The iv injections of a novel M2-R subtype agonist, 6 beta-acetoxy nortropane (6 beta-AN) 2, 5, and 20 micrograms.kg-1 caused decreases in RR, MVV, and pO2 and an increase of pCO2. The actions of 6 beta-AN were antagonized by iv pretreatment with AF-DX116 ¿11-2 [[2-[(diethylamino)methyl]-1-piperidinyl] acetyl]-5, 11-dihydro-6H[2,3-b][1,4]benzodiazepine-6-one, 0.5 mg.kg-1¿ and atropine (Atr, 2 mg.kg-1). Similar results were obtained when smaller doses of Pil (0.2, 0.4, and 0.8 mg.kg-1) and 6 beta-AN (0.25, 0.5, and 1 microgram.kg-1) were injected into the vertebral artery. Pir and Sco also antagonized the excitatory effects of Pil, and AF-DX116 and Atr antagonized the inhibitory effects of 6 beta-AN on respiration.

CONCLUSION

Stimulating M1-R of the respiratory center caused excitation of the respiration while stimulating the M2-R subtype caused inhibition of the respiration.

Relationship between muscarinic receptor subtypes and cyclic nucleotides in pons-medulla oblongata

AIM

To study the relationship between muscarinic receptor (M-R) subtypes and cyclic nucleotides in pons-medulla oblongata (MeOb).

METHODS

The contents of cGMP and cAMP in Sprague-Dawley rat pons-MeOb, cerebellum and cerebral cortex were assayed by radioimmunoassay and competitive protein-binding assay, respectively, after ip injections of drugs. Control rats were given ip normal saline.

RESULTS

M1-R agonist pilocarpine (6, 15 mg kg-1, ip) increased the content of cGMP in the pons-MeOb and cerebral cortex, but did not bring about any noticeable change in the cAMP content. The increase of cGMP was antagonized by ip pirenzepine or scopolamine. On the other hand, ip M2-R agonist 6 beta-acetoxy nortropane (6 beta-AN) 25 micrograms kg-1 reduced not only cAMP contents in the pons-MeOb and cerebellum but also cGMP contents in the pons-MeOb and cerebral cortex, while 6 beta-AN 12 micrograms kg-1 only lowered cAMP content. The decreases of cGMP and cAMP induced by 6 beta-AN were antagonized by ip AF-DX 116 or atropine, respectively.

CONCLUSION

Stimulation of M1-R causes the increase of cGMP and that of M2-R induces the decreases of both cGMP and cAMP in the pons-MeOb.

[Inhibitory effect and mechanism of scopolamine on respiration]

In conscious rabbits, dogs and anaesthetized dogs, the respiratory frequency (FR), tidal volume (Vt) and minute ventilation (Vm) were determined in order to confirm whether the respiratory effect of scopolamine is stimulatory or inhibitory. Arterial blood samples were taken intermittently and analyzed for Po2, Pco2 and pH. When scopolamine was injected i.c.v., i.a. and i.v., the decrease of FR, Vt, Vm and Po2 and the increase of Pco2 were observed in two animals. When the drug was given in clinical doses used for treating respiratory failure, the effect was seen still observable. The results indicate that scopolamine inhibits respiration. Moreover, it was observed that excitatory effect of pilocarpine on respiration can be antagonized by scopolamine, but the inhibitory effect of 6 beta-acetoxy nortropane can not be antagonized, on the contrary, can be coordinated. The above results suggest that respiratory inhibition induced by scopolamine may be related to blocking M1-R of the respiratory center.

[Effects of dl-tetrahydropalmatine on blood pressure and norepinephrine and epinephrine contents in peripheral tissues]

Administration of dl-tetrahydropalmatine (THP) i.v., ip, and ig lowered the pressure and concurrently slowed the heart rate in anesthetized rats. The hypotensive and bradycardic effects were not produced by injecting THP into the vertebral artery in anesthetized rabbits. These results suggest that the site of hypotensive action of THP may not be a central one. The HPLC coupled with electrochemical detection showed that the contents of norepinephrine (NE) in the heart, aorta, and femoral artery and epinephrine (E) in the adrenal gland were markedly reduced by THP (P < 0.01). A positive correlation was found between the hypotensive effect and the reduction of NE in the aorta and femoral artery (r = 0.97, P < 0.01).