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Biomedical subjects

D L Hoffman

Publications and source records attributed to D L Hoffman.

49 records · Page 3Linked to original sources
PubMed1972

Short- and long-term effects of estrogen and synthetic anabolic hormone in postmenopausal osteoporosis.

In 29 women with postmenopausal osteoporosis, the proportion of total bone surface undergoing resorption or formation was evaluated by microradiography of iliac crest biopsy samples before and after short-term (2(1/2)-4 months) and long-term (26-42 months for estrogen and 9-15 months for anabolic hormone) treatment. After estrogen administration, values for bone-resorbing surfaces decreased, although less prominently after long-term than after short-term therapy. The magnitude of this decrease was positively correlated with the pretreatment value for bone-resorbing surfaces (P < 0.001). When the pretreatment value for bone-resorbing surfaces was used as a covariable, estrogen and anabolic hormone appeared to be equally effective. For bone-forming surfaces, short-term therapy with either hormone had no effect but long-term therapy significantly decreased the values. Serum immunoreactive parathyroid hormone (IPTH) increased significantly after estrogen therapy; the change in IPTH was inversely related to the change in serum calcium (P < 0.001, sign test). We conclude that the primary effect of sex hormones in postmenopausal osteoporosis is to decrease the increased level of bone resorption, perhaps by decreasing the responsiveness of bone to endogenous parathyroid hormone. However, this favorable effect, at least in part, is negated after long-term treatment by a secondary decrease in bone formation. Our data are consistent with the concept that the maximal benefit that can be derived from sex hormone therapy in postmenopausal osteoporosis is arrest or slowing of the progession of bone loss.

Aged↗
PubMedDate not supplied

Morphine, beta-endorphin and [D-Ala2] Met-enkephalin inhibit oxytocin release by acetylcholine and suckling.

Morphine inhibits suckling-induced oxytocin (OT) release in lactating mice. Since beta-endorphin and enkephalins have several actions in common with morphine, the action of these opioid peptides on OT release was investigated. In anesthetized lactating rats, OT release was achieved by intraventricular injection of acetylcholine (ACh) or by the physiological stimulus of suckling. The amount of OT released was estimated by comparing milk-ejection responses to these stimuli to those following known amounts of intravenous (IV) OT. Both beta-endorphin and [D-Ala2]Met-enkephalin inhibited ACh-induced and suckling-induced OT release. Naloxone antagonized opiate inhibition in both cases.

Acetylcholine↗
PubMedDate not supplied

How to acquire customers on the Web.

Most retailers on the Web spend more to acquire customers than they will ever get back in revenue from them. Many think that sky-high spending on marketing is necessary to stake out their share of Internet space. But is it really? How do retailers know how much to pay? Consider CDnow, which has developed a multifaceted customer-acquisition strategy that reflects a clear understanding of the economics of an on-line business. At the heart of its strategy is affiliate marketing, a concept the company pioneered. Under its BuyWeb program, anyone can put a link to CDnow on his or her Web site, and if a customer uses that link to arrive at CDnow and make a purchase, the referring site owner gets a percentage of the sale. CDnow pays no money if no sale is made, which makes the marketing program completely efficient. But CDnow didn't stop there. Being a Web store, it had complete data on the number of visitors to its site and what they bought, which it used to work out the lifetime value of an average customer. CDnow used that figure to determine how much to wager on the expensive and risky world of traditional advertising to reach a wider audience that wasn't already on-line. CDnow's experience, still a work in progress, contradicts John Wanamaker's oft-quoted lament: "I know half the money I spend on advertising is wasted, but I can never find out which half." As the CDnow example demonstrates, there is a way to find out which half really works.

Commerce↗
PubMedDate not supplied

Maxillary canine impaction in patients with transverse maxillary deficiency.

Extensive literature exists concerning impacted maxillary canines. Tooth-size/arch-size discrepancy (lack of space) is a common etiologic factor of impacted canines. No studies exist documenting transverse maxillary deficiency as a causative factor for impacted canines. The purpose of this study was to determine whether patients with impacted maxillary canines have transverse deficiency and if other factors, such as arch length, arch perimeter, and arch form contribute to canine impaction. Fifty-seven (57) subjects with eighty-one (81) impacted maxillary canines were compared to one hundred-three (103) nonimpacted subjects. Intermolar (IM) and intercanine (IC) width, arch length (AL), arch perimeter (AP), and arch form were recorded for each subject. The experimental and control groups were compared using a Z test and Chi-square analysis. Results indicate subjects with canine impactions demonstrate profound transverse maxillary deficiency located in the anterior portion of the dental arch: No significant difference in arch form is noted between the experimental and control groups (p > 0.05).

Cephalometry↗