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Biomedical subjects

H D Hall

Publications and source records attributed to H D Hall.

At least 19 recordsLinked to original sources
PubMed1992

Effects of nerve growth factor on cyclocytidine-induced growth responses of sympathectomized parotid or parotid of partially desalivated rat.

Cyclocytidine (CC), a potent antitumor agent, caused a 2.4- to 3.9-fold increase in [3H]thymidine uptake of rat parotid gland after 3 days of daily administration of the CC in a dose of 500 mg/kg body weight. Gland weight also was increased. Ablation of the submandibular-sublingual glands prior to initiation of the CC regimen prevented the usual CC-induced increase in [3H]thymidine uptake but this inhibition was partially reversed when nerve growth factor (NGF) was administered with the CC; values for [3H]thymidine uptake into parotid DNA were 81, 54, and 73% of those of glands of intact CC-treated rats. Submandibular gland ablation did not prevent the usual CC-induced increase in parotid size, and administration of NGF had no effect. Sympathectomy of the salivary glands also inhibited the thymidine increase in parotid gland usually induced by CC but in addition it also inhibited the usual CC-induced increase in gland weight. NGF, however, failed to reverse the effects of sympathectomy on [3H]thymidine uptake or gland size: both remained at the same level observed in sympathectomized parotid not given NGF.

Ancitabine↗
PubMed1992

Nerve growth factor effects on inhibition by submandibular gland ablation or autonomic denervation of activity-induced parotid growth.

Present data confirm our earlier report that an increase in [3H]thymidine incorporation into DNA of parotid gland occurs with reintroduction of solid chow to rats previously maintained on liquid diet; if, however, the submandibular-sublingual glands are removed prior to the dietary substitution, the increase is prevented (present data and [19]). In addition, present data show that administration of nerve growth factor (NGF) to partially sialoadenectomized rats during the 2-day period of dietary change from liquid to solid diet restores thymidine values to the high levels observed following the dietary change in intact animals. However, the increase in gland size that accompanied the change in dietary consistency was not prevented by prior submandibular gland ablation, and administration of NGF had no influence on gland size or cell size. The removal of both the sympathetic and parasympathetic nerves to the parotid gland prior to the dietary manipulation also suppressed [3H]thymidine incorporation into parotid, and values did not differ from chow controls. The data show that NGF, a submandibular growth factor, has a prominent role in regulation of the autonomically-mediated hyperplastic response. However, neither the submandibular gland nor NGF has an important role in regulation of the increase in gland size that also accompanies the dietary change.

Aging↗
PubMed1992

Effects of selective denervation and nerve growth factor on activity-mediated growth of rat parotid gland.

A dietary change from all liquid to solid food is followed by an average increase of 200% in [3H]thymidine uptake into the parotid gland of rat. However, removal of either the parasympathetic (Px) or the sympathetic (Sx) innervation to the parotid gland prior to the dietary change resulted in a partial inhibition of the increase; values for the parasympathectomized gland were 51% of those of the innervated gland, and values of the sympathectomized parotid gland were 42% of those of the innervated gland. Removal of both autonomic nerves caused a complete inhibition. Initiation of nerve growth factor (NGF) injection (1 microgram/kg body wt, two times daily for the 2 days of chow refeeding) at the time of chow refeeding had no effect on completely or partially denervated glands, and thymidine values for the denervated parotid gland of rats given NGF did not differ statistically from those of rats not given NGF. With parasympathectomy, sympathectomy, and complete denervation, weight of parotid gland was decreased from that of innervated glands, and administration of NGF had no effect on the denervation-induced decreases. The data show that both branches of the innervation to parotid gland must be intact to ensure a maximal increase in thymidine uptake with the dietary change from liquid to solid food. The level of the enzyme, beta 1-4 galactosyltransferase, involved in proliferation, also depended on the presence of intact nerves. Enzyme activity of innervated parotid gland showed an average increase of 200% with chow refeeding of rats previously on liquid diet, but with Px, the average increase was 51% of that of the innervated parotid, and with Sx, it was 41%. NGF administration did not cause any change in levels of this enzyme in any Px or PxSx parotid gland and only a small change in Sx parotid; it did increase levels of this enzyme in parotid of rats without submandibular-sublingual glands.

Animals↗
PubMed1991

Comparison of cyclocytidine and sympathetic nerve induced changes in norepinephrine and adrenoceptors in salivary glands.

Norepinephrine (NE) concentration of parotid and submandibular glands of young rats was reduced 51% and 39%, respectively at 1 h, and 60% and 47% at 2 h after i.p. administration of a single dose (500 mg/kg body weight) of the anti-tumor agent, cyclocytidine (CC). For adult rats, the reductions were 44% and 46%, respectively, at 1 h and 54% and 49% at 2 h. This decrease from controls was generally similar to the decrease induced following 1 and 2 h of electrical stimulation (square wave pulses of 4 V, 5 ms duration, and frequency of 16 Hz) of the sympathetic innervation to these glands (young rats, 59% and 58% at 1 h; 66% and 63% at 2 h; for adult rats, 51% and 55% at 1 h and 69% and 53% at 2 h for parotid and submandibular, respectively). The changes in density of beta-adrenoceptors induced by direct nerve stimulation also corresponded to the changes induced by CC (CC induced a decrease in parotid of 12%, compared with a decrease of 11% with electrical stimulation; a 15% and 18% reduction in number of beta-adrenoceptors of submandibular gland was found at 1 h after CC and electrical stimulation, respectively). Compelling evidence for the mechanism of CC action was thus established, showing that CC mimics effects of sympathetic nerve stimulation (inducing reduction in NE concentration and transient change in beta-adrenoceptor density) by causing release of NE from sympathetic nerve endings.

Ancitabine↗
PubMed1991

Inhibition of activity-induced parotid growth by submandibular gland ablation or autonomic denervation.

When solid chow was reintroduced for 2 days to rats previously maintained on an all-liquid diet, [3H]thymidine incorporation into rat parotid gland was 2.4-4.4 times that of chow-fed or liquid-fed animals. When the submandibular-sublingual glands were removed before the change in diet from liquid to solid food, values for [3H]thymidine incorporation of parotid gland were not statistically different from those of chow-fed rats: the increase was completely prevented. The increase in gland size that accompanied the change in dietary consistency was not prevented by prior submandibular gland ablation; [3H]uridine incorporation was also not different from that of chow controls. The removal of both the sympathetic and parasympathetic nerves to the parotid gland before the dietary manipulation also suppressed [3H]thymidine incorporation into parotid, and values did not differ from chow controls. Moreover, the return to normal gland size (chow level) also was prevented by autonomic denervation. The data show an important role of the submandibular gland in regulation of the thymidine increase associated with the enhanced parotid activity that accompanies the change from liquid to solid diet. However, the submandibular gland does not have an important role in regulation of the increase in gland size that also accompanies the dietary change, whereas the autonomic nerves have an important role in regulation of hypertrophy and hyperplasia of parotid gland.

Animal Feed↗
PubMed1991

Effects of varying frequency of sympathetic stimulation on chloride and amylase levels of saliva elicited from rat parotid gland with electrical stimulation of both autonomic nerves.

Simultaneous stimulation of the parasympathetic and sympathetic nerves to the parotid gland of rats elicited saliva at a rate dependent on the frequency of sympathetic stimulation when parasympathetic frequency was maintained at 16 Hz. The flow rate was lowest at 2 Hz (sympathetic), moderate at 5 Hz, and highest at 16 Hz. Cl concentration of the saliva evoked with stimulation of both nerves was highest at the highest frequency and flow rate (maintained at the level of 102 mEq/liter, for 35 min) and lowest at 2 Hz (declining from 40 mEq/liter initially to 28 mEq/liter). With sympathetic nerve stimulation alone, Cl concentration ranged from 27 to 58 mEq/liter when frequency was varied from 2 to 16 Hz, and with parasympathetic stimulation alone (16 Hz), it ranged from 132 to 124 mEq/liter. Amylase concentration of sympathetically elicited saliva was, in contrast, highest at 2 Hz (1.5 times the level at 5 Hz, and twice the level at 16 Hz), and nearly 18-38 times that seen with parasympathetic stimulation alone. The same pattern was found when both nerves were stimulated, and at 2 Hz (sympathetic), amylase concentration was 1.6 times the level at 5 Hz and 2.6 times the level at 16 Hz. When the two nerves were simultaneously stimulated, the total amount of amylase secreted over 35 min was twice as high as that observed with sympathetic nerve stimulation alone, at any frequency. The relation of frequency to norepinephrine concentration was examined. There was no consistent difference in norepinephrine concentration related to variation in frequency of sympathetic stimulation. Only when both nerves were stimulated at 16 Hz was there a statistically significant reduction in norepinephrine concentration of 46%. A relation between frequency of sympathetic stimulation, flow rate, amylase concentration, and Cl concentration was established, but these changes could not be directly correlated with quantitative differences in norepinephrine concentration.

Amylases↗
PubMed1991

Modification of cyclocytidine-induced changes in [3H]thymidine incorporation and weight of parotid gland by partial sialoadenectomy.

Cyclocytidine (CC), a potent antitumor agent, caused a 2.3- to 5.0-fold increase in [3H]thymidine uptake of rat parotid gland after 3 days of daily administration of 500 mg/kg body wt. Gland weight also showed a 47-67% increase from that of controls. Ablation of the submandibular-sublingual glands prior to initiation of the CC regimen prevented the usual CC-induced increase in [3H]thymidine uptake, but did not inhibit the increase in gland size. It is postulated that CC-induced parotid hyperplasia requires an initial release of growth factors from the submandibular gland; however, enlargement of the parotid gland by CC is independent of such factors.

Ancitabine↗
PubMed1990

Chloride concentration of rat parotid saliva evoked by electrical stimulation of parasympathetic or sympathetic nerves with or without antagonists.

Chloride (Cl) of saliva evoked by electrical stimulation of the parasympathetic nerve to parotid gland was from two to seven times higher than that elicited with sympathetic nerve stimulation; [Cl] remained elevated (125-135 mEq/liter) for 60 min of parasympathetic nerve stimulation, whereas Cl of sympathetically evoked saliva decreased from high levels of 58 to 15 to 20 mEq/liter. The administration of propranolol, the beta-adrenergic antagonist, 20 min prior to initiation of sympathetic nerve stimulation resulted in saliva with Cl of 100 mEq/liter; when phentolamine, the alpha-adrenergic antagonist was administered prior to sympathetic nerve stimulation, [Cl] was 48-35 mEq/liter. Values with the beta-agonist, isoproterenol, were about 35 mEq/liter, whereas phenylephrine, an alpha-adrenergic agonist, evoked saliva with Cl ranging from 113 to 85 mEq/liter. Flow rate was very high with parasympathetic nerve stimulation and low with sympathetic nerve stimulation, but [Cl] with beta-blockade was not flow dependent: flow was very low but Cl high. Cl secretion is principally regulated by activation of cholinergic and alpha-adrenergic receptors.

Adrenergic alpha-Antagonists↗
PubMed1990

Audiometric assessment of patients with painful TMJ internal derangements: failure of audiometry to change following arthrotomy.

Thirteen patients with proven internal derangements of 16 temporomandibular joints were scheduled for arthrotomy. The patients' perception of otologic symptoms were recorded before surgery, and hearing was evaluated audiometrically both before and after surgery. There was no significant correlation between otologic symptoms and ipsilateral painful internal derangement of the temporomandibular joint. Perceived hearing loss was substantiated in only about half of the instances. Further, only about half of the ears with measured hearing loss (sensorineural) were associated with a painful internal derangement. Arthrotomy did not change any of the audiograms.

Adolescent↗
PubMed1989

Autonomic receptors and cyclic nucleotides of rat parotid gland following simultaneous electrical stimulation of its parasympathetic and sympathetic nerves.

[3H]dihydroalprenolol and [3H]quinuclidinylbenzilate binding of membranes of rat parotid gland were generally unchanged after 10, 15, 30, or 60 min of simultaneous electrical stimulation of the parasympathetic and sympathetic nerves to the gland, although stimulation of either nerve separately caused nerve-specific changes in both. Concentrations of cyclic nucleotides of the gland were, however, increased significantly from levels of the unstimulated parotid gland. Cyclic GMP showed a 10-fold increase after 10 min of stimulation, whereas only a 2-fold increase in cyclic AMP was found at this time. The increases were maintained, albeit at reduced levels, at 15 and 30 min also but by 60 min both were not different from levels of the unstimulated gland. The increases induced by separate stimulation of each nerve were greater but nerve specific, and the changes induced with simultaneous stimulation tended to reflect a reigning influence of one nerve on the other.

Animals↗
PubMed1978

Neural regulation of compensatory enlargement of the parotid gland of the rat.

The role of the innervation in mediating compensatory enlargement of the parotid gland of the rat after partial desalivation was examined. The results of denervation experiments show that full compensatory growth requires both parasympathetic and sympathetic innervation. The presence of the parasympathetic innervation alone results in an increase in the number of cells, but not the size of the cells. The sympathetic innervation alone does not mediate either response. We, therefore, conclude that the two types of innervation have a synergistic action on the parotid to produce the maximal compensatory response, which includes an increase in both number and size of acinar cells.

Animals↗
PubMed1977

Functional mediation of compensatory enlargement of the parotid gland.

The role of functional activity in mediating compensatory enlargement of the parotid gland after removal of the other major salivary glands was investigated. Increased levels of activity were achieved by feeding rats a bulk diet. Conversely, a liquid diet was used to reduce the functional demands on the parotid. It was found that the liquid diet completely prevented the compensatory response from occurring. Bulk diet, on the other hand, caused an even greater compensatory response than did the standard chow diet. Compensatory enlargement of the parotid, therefore, depends on its functional activity and not on other, e.g., humoral factors dissociated from function. The character of the cellular response in compensatory enlargement was also examined. The chow diet caused compensatory enlargement by an increase in cell size with little, if any, increase in cell number.

Animals↗
PubMed1976

Neurally mediated increase in mitosis and DNA of rat parotid with increase in bulk of diet.

A transient burst of mitosis was induced in rat parotid gland 2 days after change from a diet of solid chow only to one consisting of 50% inert cellulose and 50% solid chow (bulk diet). Mitosis was thus induced when glandular activity was changed from normal levels (solid chow) to levels greater than normal (bulk diet). Elimination of either autonomic pathway inhibited the mitotic response, but elimination of the parasympathetic had the greater inhibitory influence. The burst of mitosis induced by bulk diet was followed by increases in total DNA (16%), RNA (24%) and weight (27%) of the gland 2 wk after the dietary change. These changes did not occur when both autonomic pathways were, or only the parasympathetic was, removed immediately prior to the dietary change. Effects of sympathectomy were less pronounced. The parasympathetic innervation has the principal role in regulation of mitosis, cell number and size, and nucleic acid content when glandular activity is increased above normal by physiological means.

Animals↗
PubMed1976

Combined anterior and posterior maxillary osteotomy.

The combined anterior and posterior maxillary osteotomy is primarily indicated for maxillary alveolar hyperplasia. Treatment planning is somewhat more complex than usual for the combined procedure. A method for developing a treatment plan is presented. In contrast to the anterior maxillary osteotomy, the technique for posterior osteotomy is relatively new and has had several recent modifications. Guidelines are presented for rational selection of a specific combined technique. The results obtained with the combined technique have not been well documented. Nonetheless, results appear to be stable and complications are infrequent.

Adolescent↗