Structural insights into the mechanism of protein transport by the Type 9 Secretion System translocon

Secretion systems are protein export machines that enable bacteria to exploit their environment through the release of protein effectors. The Type 9 Secretion System (T9SS) is responsible for protein export across the outer membrane (OM) of bacteria of the phylum Bacteroidota. Here we trap the T9SS of Flavobacterium johnsoniae in the process of substrate transport by disrupting the T9SS motor complex. Cryo-EM analysis of purified substrate-bound T9SS translocons reveals an extended translocon structure in which the previously described translocon core is augmented by a periplasmic structure incorporating the proteins SprE, PorD and a homologue of the canonical periplasmic chaperone Skp. Substrate proteins bind to the extracellular loops of a carrier protein within the translocon pore. As transport intermediates accumulate on the translocon when energetic input is removed, we deduce that release of the substrate-carrier protein complex from the translocon is the energy-requiring step in T9SS transport.

Aberrant Topologies of Bacterial Membrane Proteins Revealed by High Sensitivity Fluorescence Labelling

The cytoplasmic membrane compartmentalises the bacterial cell into cytoplasm and periplasm. Proteins located in this membrane have a defined topology that is established during their biogenesis. However, the accuracy of this fundamental biosynthetic process is unknown. We developed compartment-specific fluorescence labelling methods with up to single-molecule sensitivity. Application of these methods to the single and multi-spanning membrane proteins of the Tat protein transport system revealed rare topogenesis errors. This methodology also detected low level soluble protein mislocalization from the cytoplasm to the periplasm. This study shows that it is possible to uncover rare errors in protein localization by leveraging the high sensitivity of fluorescence methods.

Biophysical characterisation of DNA origami nanostructures reveals inaccessibility to intercalation binding sites

Intercalation of drug molecules into synthetic DNA nanostructures formed through self-assembled origami has been postulated as a valuable future method for targeted drug delivery. This is due to the excellent biocompatibility of synthetic DNA nanostructures, and high potential for flexible programmability including facile drug release into or near to target cells. Such favourable properties may enable high initial loading and efficient release for a predictable number of drug molecules per nanostructure carrier, important for efficient delivery of safe and effective drug doses to minimise non-specific release away from target cells. However, basic questions remain as to how intercalation-mediated loading depends on the DNA carrier structure. Here we use the interaction of dyes YOYO-1 and acridine orange with a tightly-packed 2D DNA origami tile as a simple model system to investigate intercalation-mediated loading. We employed multiple biophysical techniques including single-molecule fluorescence microscopy, atomic force microscopy, gel electrophoresis and controllable damage using low temperature plasma on synthetic DNA origami samples. Our results indicate that not all potential DNA binding sites are accessible for dye intercalation, which has implications for future DNA nanostructures designed for targeted drug delivery.

The analysis of human operant behavior: A brief census of the literature: 1958-1981

A census involving several major journals was conducted to survey the content and scope of the experimental analysis of human behavior. While the percentage of reports involving human subjects published each year in JEAB has lacked consistency, it was shown that JEAB has been the primary outlet for human work among the journals surveyed. Few areas of interest within the study of human behavior have received extensive scrutiny. The normal adult (typically undergraduate students) has been the preferred subject for human research. The results of a citation analysis of JEAB reports featuring human research are also presented.

Matching-based hedonic scaling in the pigeon

Four slightly hungry pigeons chose between pairs of grains in a Findley concurrent choice procedure. For Condition I, choice involved hemp versus buckwheat; for Condition II, wheat versus buckwheat; and for Condition III, hemp versus wheat. In all conditions, frequency of reinforcement was arranged according to concurrent variable-interval variable-interval schedules. On the assumption that subjects matched their behavior and time distributions to those of reinforcer value, the choice functions obtained in Conditions I and II were transformed to yield estimates of values of hemp and wheat relative to buckwheat. These, in turn, provided predictions about behavior and time allocation in Condition III. In general, the predicted outcomes were close to those actually obtained. The results evidence the effectiveness of matching-based hedonic scales in the prediction of choice between qualitatively different reinforcers.

Effects of instructional constraints on human fixed-interval performance

Several groups of human subjects were exposed to a variety of experimental conditions involving a fixed-interval 27-second schedule of reinforcement in compound with instructions to constrain in the number of responses within the interreinforcement interval and/or the duration of the experimental session. One group was further exposed to a contingency involving the placement of responses within the IRI. A diversity of patterns of performance was observed, including those typically associated with animal subjects exposed to FI schedules. Generally, the imposition of instructions to minimize session duration reduced post-reinforcement pausing and increased overall reinforcement density from those levels obtained with only instructions to expend a given number of responses per reinforcer. The results are seen to underscore the sensitivity of human fixed-interval performance and the contribution of extra-experimental contingencies.

Noradrenergic function and clinical outcome in antidepressant pharmacotherapy

Controversy remains regarding the role of noradrenergic systems in determining clinical response to antidepressant pharmacotherapy. Pineal gland production of melatonin can serve as a physiologic index of noradrenergic function. The aim of this study was to examine the effects of antidepressant treatment on 24-hour urinary excretion of the principle metabolite of melatonin, 6-sulfatoxymelatonin in treatment responders and nonresponders. Twenty-four outpatients meeting DSM-III-R criteria for Major Depression received treatment with either fluvoxamine or imipramine for 6 weeks while participating in a placebo-controlled double-blind clinical trial. Twenty-four hour excretion of 6-sulfatoxymelatonin was measured at baseline and at the conclusion of the treatment trial. Changes in urinary excretion of 6-sulfatoxymelatonin distinguished antidepressant responders from nonresponders, with a significant increase observed in the former group and a significant decrease in the latter. The degree of clinical response was correlated with the change in 6-sulfatoxymelatonin excretion. These results suggest that enhanced noradrenergic function may play an important role in determining clinical response to antidepressant pharmacotherapy.

HOX genes in human lung: altered expression in primary pulmonary hypertension and emphysema

HOX genes belong to the large family of homeodomain genes that function as transcription factors. Animal studies indicate that they play an essential role in lung development. We investigated the expression pattern of HOX genes in human lung tissue by using microarray and degenerate reverse transcriptase-polymerase chain reaction survey techniques. HOX genes predominantly from the 3' end of clusters A and B were expressed in normal human adult lung and among them HOXA5 was the most abundant, followed by HOXB2 and HOXB6. In fetal (12 weeks old) and diseased lung specimens (emphysema, primary pulmonary hypertension) additional HOX genes from clusters C and D were expressed. Using in situ hybridization, transcripts for HOXA5 were predominantly found in alveolar septal and epithelial cells, both in normal and diseased lungs. A 2.5-fold increase in HOXA5 mRNA expression was demonstrated by quantitative reverse transcriptase-polymerase chain reaction in primary pulmonary hypertension lung specimens when compared to normal lung tissue. In conclusion, we demonstrate that HOX genes are selectively expressed in the human lung. Differences in the pattern of HOX gene expression exist among fetal, adult, and diseased lung specimens. The altered pattern of HOX gene expression may contribute to the development of pulmonary diseases.

Interaction of procedural factors in human performance on yoked schedules

The differential effects of reinforcement contingencies and contextual variables on human performance were investigated in two experiments. In Experiment 1, adult human subjects operated a joystick in a video game in which the destruction of targets was arranged according to a yoked variable-ratio variable-interval schedule of reinforcement. Three variables were examined across 12 conditions: verbal instructions, shaping, and the use of a consummatory response following reinforcement (i.e., depositing a coin into a bank). Behavior was most responsive to the reinforcement contingencies when the consummatory response was available, responding was established by shaping, and subjects received minimal verbal instructions about their task. The responsiveness of variable-interval subjects' behavior varied more than that of variable-ratio subjects when these contextual factors were altered. Experiment 2 examined resistance to instructional control under the same yoked-schedules design. Conditions varied in terms of the validity of instructions. Performance on variable-ratio schedules was more resistant to instructional control than that on variable-interval schedules.

Carpal tunnel syndrome in women undergoing reduction mammaplasty

Women with mammary hypertrophy who present for reduction mammaplasty have several well-described musculoskeletal complaints, but a high prevalence of carpal tunnel syndrome has not been reported. We identified 151 patients from a plastic surgery practice who underwent reduction mammaplasty from 1994 to 1996. To this group we added a convenience sample of 64 women volunteers with relatively smaller breasts (brassiere cup size B or smaller). We questioned the entire group about specific symptoms and examined them using standard provocative tests. Carpal tunnel syndrome was defined as the coexistence of symptoms and at least two physical examination findings. We examined its association with breast size, age, race, and body mass index. Stepwise logistic regression was used to determine which physical characteristics were predictive of the condition. Carpal tunnel syndrome was found in 30 patients (19.9 percent) (95 percent confidence interval, 13.8 to 27.1) and in none of the women in the convenience sample. Breast size and, to a lesser degree, body mass index were found to be highly significant predictors of carpal tunnel syndrome. After controlling for breast size, race was also significant. Breast size displayed an independent risk ratio of 6.67 when comparing the upper quartile of size to the lower quartiles. There is a markedly higher prevalence of carpal tunnel syndrome in women who present for reduction mammaplasty than in those with smaller breasts. Breast size was a significant predictor of carpal tunnel syndrome.

Hippocampal volume reduction in major depression

OBJECTIVE

Elevated levels of glucocorticoids in depression have been hypothesized to be associated with damage to the hippocampus, a brain area involved in learning and memory. The purpose of this study was to measure hippocampal volume in patients with depression.

METHOD

Magnetic resonance imaging was used to measure the volume of the hippocampus in 16 patients with major depression in remission and 16 case-matched nondepressed comparison subjects.

RESULTS

Patients with depression had a statistically significant 19% smaller left hippocampal volume than comparison subjects, without smaller volumes of comparison regions (amygdala, caudate, frontal lobe, and temporal lobe) or whole brain volume. The findings were significant after brain size, alcohol exposure, age, and education were controlled for.

CONCLUSIONS

These findings are consistent with smaller left hippocampal volume in depression.

Issues in balancing teenage clients' confidentiality and reporting statutory rape among Kansas Title X clinic staff

Through Federal welfare reform, Congress directed states to aggressively enforce statutory rape laws. Family planning professionals deal with many adolescent clients, and their support for such enforcement or willingness to report is unclear. The authors of this study examined current attitudes and practices of family planning program managers (FPPMs) about statutory rape law enforcement, including current reporting practices. In 1997, all 77 local Kansas Title X FPPMs were surveyed. Structured telephone interviews were conducted with 10 FPPMs to add detail to quantitative responses. Sixty-eight FPPMs responded to the written survey (88%). Of these, 79% supported aggressive enforcement, and 43% thought enforcement would reduce adolescent pregnancy rates. With increased enforcement, 38% believed teenagers would be discouraged from seeking reproductive health care, compared to 41% who believed they would not. Among key informants, all of whom were FPPMs, willingness to report cases was mixed, with those who would report wanting the flexibility to judge on a case-by-case basis. For those not reporting cases, confidentiality concerns overrode beliefs in any positive outcome of enforcement. Kansas Title X FPPMs strongly supported aggressive enforcement, but had mixed beliefs about negative consequences. Among those interviewed, there were also mixed beliefs and practices about reporting. Reporting from FPPMs will be sporadic and arbitrary unless protocols are developed and laws are clarified.

Interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements

In a study involving 10 different sites, independent results of measurements of ultrasonic properties on equivalent tissue-mimicking samples are reported and compared. The properties measured were propagation speed, attenuation coefficients, and backscatter coefficients. Reasonably good agreement exists for attenuation coefficients, but less satisfactory results were found for propagation speeds. As anticipated, agreement was not impressive in the case of backscatter coefficients. Results for four sites agreed rather well in both absolute values and frequency dependence, and results from other sites were lower by as much as an order of magnitude. The study is valuable for laboratories doing quantitative studies.

Tryptophan-depletion challenge in depressed patients treated with desipramine or fluoxetine: implications for the role of serotonin in the mechanism of antidepressant action

BACKGROUND

Brain serotonin (5-HT) content is dependent on plasma levels of the essential amino acid, tryptophan (TRP). We have previously reported that rapid TRP depletion more frequently reversed the antidepressant response to monoamine oxidase inhibitors and 5-HT reuptake inhibitors than to desipramine (DMI). This study further investigates the relationship of relapse during TRP depletion to antidepressant type in nonrefractory, depressed patients randomly assigned to treatment with either DMI or fluoxetine (FLU).

METHODS

Fifty-five drug-free depressed (DSM-III-R) patients were randomly assigned to antidepressant treatment with either DMI or FLU. All patients were either treatment naive (n = 34) or had previously received successful antidepressant treatment (n = 21). During the treatment phase, 35 patients had therapeutic responses by predetermined criteria (DMI 18/25; FLU 17/23) and 30 of these (15 DMI responders and 15 FLU responders) went on to TRP depletion testing. Patients received two 2-day test sessions involving administration of similar amino acid drinks. One session led to rapid TRP depletion and the other did not. Behavioral ratings [Hamilton Depression Scale (HDRS)] and plasma for TRP levels were obtained prior to, during, and after testing. Relapse was defined as a 50% increase in HDRS with total < or = 17.

RESULTS

Total and free TRP decreased 70% to 80% 5 hours after the TRP-free drink. While 8/15 FLU responders relapsed, only 1/15 of the DMI responders relapsed. No patient experienced significant depressive symptoms during control testing.

CONCLUSIONS

Rapid depletion of plasma TRP transiently reverses the antidepressant response in many patients on FLU but not DMI. Depressive relapse during TRP depletion appears to be more related to antidepressant type than to patient variables since patients were randomly assigned to the two treatments. Antidepressant response to FLU appears to be more dependent on 5-HT availability than that of DMI, suggesting that antidepressants mediate their therapeutic effects through different mechanisms.

The use of pindolol with fluoxetine in the treatment of major depression: final results from a double-blind, placebo-controlled trial

BACKGROUND

Preliminary reports have suggested that concomitant institution of pindolol and serotonin reuptake inhibitors robustly hastens clinical response; however, contradictory evidence from a randomized double-blind, controlled trial was recently reported by this group in a population of depressed patients who were prescribed fluoxetine and pindolol. Herein, we report final results from an extended sample size.

METHODS

Drug-free outpatients with a major depressive episode were randomized in a double-blind manner to one of two treatment conditions: fluoxetine (20 mg daily) with pindolol (7.5 to 10 mg daily) or fluoxetine (20 mg daily) with placebo. After 6 weeks, patients were followed for 3 more weeks in a single-blind manner, on fluoxetine and placebo pindolol.

RESULTS

Eighty-six patients completed at least 1 or more weeks on protocol, with 45 and 41 patients randomized to the pindolol and placebo groups respectively. After 2 weeks on protocol, partial remission (i.e., at least 50% decrease in depression rating scores from baseline) rates for pindolol (16%) and placebo (19%) groups were comparable. By the study's end, a partial remission was achieved, at least transiently, for 67% of the pindolol group and 80% of the placebo group. Pindolol treatment was associated with statistically significant reduction in blood pressure and pulse as compared to the control group. The two groups did not have overall differences in rates of attrition, time to response, and side effects.

CONCLUSIONS

In accord with our previously published findings, these extended results do not support the efficacy of pindolol in hastening clinical response to fluoxetine in a patient population with predominantly chronic and recurrent depression.

Transient depressive relapse induced by catecholamine depletion: potential phenotypic vulnerability marker?

BACKGROUND

Although state-related alterations in catecholamine function have been well-described in depressed subjects, enduring abnormalities have been less reliably identified. In our study, medication-free subjects with fully remitted major depression underwent a paradigm of catecholamine depletion, via use of the tyrosine hydroxylase inhibitor alpha-methylparatyrosine.

METHOD

Subjects underwent 2 sets of testing conditions in a double-blind, random-ordered, crossover design, approximately 1 week apart. They underwent active catecholamine depletion (via oral administration of 5 g alpha-methylparatyrosine) or sedation-controlled, sham catecholamine depletion (via oral administration of 250 mg diphenhydramine hydrochloride), during a 2-day observation. Serial mood ratings and blood samples were obtained.

RESULTS

Fourteen subjects completed the active testing condition; 13 completed sham testing. Subjects experienced marked, transient increases in core depressive and anxiety symptoms, as demonstrated by a mean 21-point increase on Hamilton Depression Rating Scale scores. Furthermore, 10 (71%) of 14 subjects fulfilled relapse criteria during active testing, whereas 1 (8%) of 13 subjects did so during sham testing. The severity of the depressive reaction correlated with baseline plasma cortisol levels (r = 0.59; P =.04).

CONCLUSIONS

Euthymic, medication-free subjects with a history of major depression demonstrate significant depressive symptoms when undergoing testing with alpha-methylparatyrosine. This depressive reaction may represent a reliable marker for a history of depression. Further work is needed to clarify the significance of this finding.

Effect of catecholamine depletion on lithium-induced long-term remission of bipolar disorder

BACKGROUND

This study investigated the effects of catecholamine depletion with alpha-methylparatyrosine (AMPT) on mood indices in patients with bipolar disorder who were in long-term remission with lithium therapy.

METHODS

Eight subjects with DSM-IV bipolar disorder currently in remission for > 3 months on lithium were included in the study. Subjects were given either AMPT or placebo, in a randomized double-blind manner, in two test sessions of 4 days each.

RESULTS

Subjects did not have any significant changes in mood during AMPT or placebo administration; however, 24-48 hours after the last active AMPT dose subjects had a transient relapse of hypomanic symptoms. Relapse of hypomanic symptoms did not correlate with increases in serum levels of homovanillic acid or 3-methoxy-4-hydroxyphenylglycol.

CONCLUSIONS

These findings suggest that the mechanism of prevention of manic relapse by long-term lithium therapy may be dependent on stability of the catecholamine system.

Issues in statutory rape law enforcement: the views of district attorneys in Kansas

CONTEXT

The 1996 federal welfare reform law calls for the reduction of adolescent pregnancy rates through aggressive enforcement of statutory rape laws at the local and state level. Yet there are few quantitative data on district attorneys' attitudes toward enforcement and related issues.

METHODS

Anonymous surveys were mailed to all 105 Kansas district attorneys in 1997; 92 surveys were returned. In-depth telephone interviews were conducted with seven of the attorneys.

RESULTS

Most of the respondents (74%) favored aggressive enforcement, but just 37% believed the public would support aggressive enforcement. Only 24% believed enforcement would reduce adolescent pregnancy. Fifty-seven percent supported the current legal age of consent in Kansas (16 years). Fifty-three percent thought the law should not specify age differences between the partners. Most (77%) believed the law should protect sexually active minors, and that paternity acknowledgments should be admissible evidence in prosecutions (78%). Only 17% believed that enforcement would discourage adolescents from seeking health care.

CONCLUSIONS

The potential impact of statutory rape prosecution on reproductive and psychological health should be considered in each case. Educating law enforcement officials about adolescent health care issues and encouraging them to consult with professionals in health and psychological fields may help to minimize the potentially negative effects of enforcement on adolescents' reproductive health.

An epidemic of Malassezia pachydermatis in an intensive care nursery associated with colonization of health care workers' pet dogs

BACKGROUND

Malassezia species are lipophilic yeasts that are emerging as nosocomial pathogens, particularly in low-birth-weight neonates who receive lipid emulsions. When a cluster of patients with Malassezia pachydermatis infection was identified in an intensive care nursery, we initiated an investigation.

METHODS

A case patient was defined as any infant in the intensive care nursery who had a positive culture for M. pachydermatis between October 17, 1993, and January 18, 1995. We conducted a cohort study to identify risk factors for colonization and infection with M. pachydermatis. We collected cultures from the infants and the health care workers and from the health care workers' pets, since this organism has been associated with otitis externa in dogs.

RESULTS

Fifteen infants met the case definition: eight with bloodstream infections, two with urinary tract infections, one with meningitis, and four with asymptomatic colonization. The case patients were significantly more likely than the other infants to weigh 1300 g or less (15 of 65 vs. 0 of 419, P<0.001). In a multivariate analysis of infants weighing 1300 g or less, the independent risk factors for colonization or infection with M. pachydermatis were a greater severity of concomitant illness (odds ratio, 19.7; P=0.001), arterial catheterization for nine or more days (odds ratio, 29.5; P=0.027), and exposure to Nurse A (odds ratio, 74.7; P=0.004). In a point-prevalence survey, 9 additional infants, 1 health care worker, and 12 of the health care workers' pet dogs had positive cultures for M. pachydermatis. The isolates from all 15 case patients, the 9 additional colonized infants, 1 health care worker, and 3 of the 12 dogs had identical patterns of restriction-fragment-length polymorphisms.

CONCLUSIONS

In this outbreak, it is likely that M. pachydermatis was introduced into the intensive care nursery on health care workers' hands after being colonized from pet dogs at home. The organism persisted in the nursery through patient-to-patient transmission.

Positron emission tomography measurement of cerebral metabolic correlates of tryptophan depletion-induced depressive relapse

BACKGROUND

Short-term depletion of plasma tryptophan has been shown to result in depressive relapse in patients with remission of major depression. Positron emission tomography and single photon emission computed tomography studies implicated the dorsolateral prefrontal cortex, orbitofrontal cortex, thalamus, and caudate nucleus in the pathogenesis of depression. The purpose of this study was to measure cerebral metabolic correlates of tryptophan depletion-induced depressive relapse.

METHODS

Patients diagnosed as having major depression (N = 21) who clinically improved with serotonin reuptake inhibitors underwent 2 test days involving tryptophan depletion or placebo, followed 6 hours later by positron emission tomography scanning with fludeoxy-glucose F18. Brain metabolism was compared in patients with (n = 7) and without (n = 14) a tryptophan depletion-induced depressive relapse.

RESULTS

Tryptophan depletion resulted in a decrease in brain metabolism in the middle frontal gyrus (dorsolateral prefrontal cortex), thalamus, and orbitofrontal cortex in patients with a depletion-induced depressive relapse (but not in patients without depletion-induced relapse). Decreased brain metabolism in these regions correlated with increased depressive symptoms. Baseline metabolism was increased in prefrontal and limbic regions in relapse-prone patients.

CONCLUSION

Specific brain regions, including the middle frontal gyrus, thalamus, and orbitofrontal cortex, may mediate the symptoms of patients with major depression.

Lack of behavioral effects of monoamine depletion in healthy subjects

This study was designed to determine the behavioral effects of a reduction in catecholamine and indoleamine function in healthy subjects. Eight healthy subjects received the tyrosine hydroxylase inhibitor, alpha-methyl-para-tyrosine (AMPT) in combination with a full-strength tryptophan-depleting amino acid drink during one 4-day test session, and AMPT and tryptophan-supplemented amino acid drink (n = 2), or a 25% strength tryptophan-depleting amino acid drink (n = 6) during a second 4-day test session. The combined administration of AMPT and the tryptophan-free amino acid drink did not produce statistically significant or even clinically noticeable changes in mood among the healthy subjects. The implications of these observations for the monoamine hypotheses of depression are discussed.

Effect of pindolol in hastening response to fluoxetine in the treatment of major depression: a double-blind, placebo-controlled trial

OBJECTIVE

In two preliminary studies, pindolol produced robust results in hastening clinical response to antidepressant drugs in depressed patients. Validity of those pilot studies was limited by use of an open-label, unblinded study design, and so the authors conducted a double-blind, placebo-controlled trial to assess the effectiveness of pindolol in hastening response to fluoxetine.

METHOD

Drug-free outpatients with major depression were concurrently treated with fluoxetine (20 mg/day) and either placebo or pindolol (5.0 mg b.i.d. or 2.5 mg t.i.d.), for 6 weeks, in a randomized, double-blind manner. After 6 weeks, all patients received fluoxetine and placebo and were followed for 3 further weeks in a single-blind manner.

RESULTS

Forty-three patients completed at least 1 week of the protocol. Rates of partial remission after 2 weeks of treatment with fluoxetine and either pindolol or placebo were 17% (four of 23 patients) and 20% (four of 20 patients), respectively. At study completion, 65% of the patients (N = 28) demonstrated at least a partial remission, and there was no difference between treatment groups. The pindolol group, but not the placebo group, demonstrated significant reductions in blood pressure and pulse rate. The average time to remission and the rates of attrition, overall response, and side effects were similar in the two groups.

CONCLUSIONS

These findings do not support the efficacy of pindolol in hastening clinical response in patients treated with fluoxetine.

The effects of age, gender, and season on serotonergic function in healthy subjects

1. Several factors, including age, gender, and season of the year, have been reported to affect physiologic indices of central serotonergic function, although some of these findings have not been consistent across groups of subjects and types of serotonergic measures. 2. The authors investigated the role that each of these variables might play in the neuroendocrine response to acute intravenous challenge with the serotonin reuptake inhibitor clomipramine (CMI) in healthy volunteers. 3. Thirty seven healthy subjects (17 women and 20 men), with an age range of 19 to 50 years, received 12.5 mg of CMI intravenously under standardized conditions. 4. The maximum change from baseline in plasma prolactin concentrations ("delta-max") was significantly related to age, after controlling for gender and season. 5. In contrast, neither gender nor season was significantly related to prolactin delta-max, after controlling for the other two variables. 6. Although the age range and sample size are relatively limited, the results from this study suggest that age, but not gender or season, may influence serotonergic function, as measured by the prolactin response to CMI challenge.

Effects of alpha-methyl-para-tyrosine (AMPT) in drug-free depressed patients

A variety of biologic studies have demonstrated abnormal regulation of the norepinephrine (NE) system in patients with major depression, suggesting a role for NE in the etiology of depression. Brain NE and dopamine levels can be rapidly reduced by blocking synthesis with the tyrosine hydroxylase inhibitor alpha-methyl-para-tyrosine (AMPT). In the current investigation, AMPT was administered to drug-free depressed patients to evaluate the effect on mood of diminished catecholamine levels. Seventeen drug-free patients meeting DSM-III-R criteria for major depressive episode were tested with AMPT and an active placebo control, diphenhydramine. Testing was accomplished in a double-blind, crossover fashion, with random assignment to test conditions. Each test included baseline evaluation, 2 days with administration of either AMPT or diphenhydramine, and a follow-up day. Diphenhydramine was used as an active control because of the significant sedation associated with AMPT. Behavioral ratings, including visual analogue scales for a variety of feeling states, the Hamilton Depression Rating Scale (HDRS), and plasma for 3-methoxy-4-hydroxyphenelethyleneglycol (MPHG) and homovanillic acid (HVA) levels, were obtained. AMPT significantly reduced plasma HVA by 70% and MHPG by 50%, but it had no significant effects on the HDRS. AMPT also significantly increased visual analogue ratings of "tired" and decreased ratings of "energetic." Diphenhydramine significantly decreased HDRS scores, but the change was small and was not clinically apparent. The lack of AMPT effects on depressed mood, in conjunction with a prior report that large reductions in plasma tryptophan do not systematically alter depressed mood, indicate that monoamine deficiency by itself is insufficient explanation of the cause of depression. The role of the noradrenergic system needs to be considered in relationship to the many other neurobiologic factors that could be involved in the pathophysiology of depression.

Clinical and biochemical effects of catecholamine depletion on antidepressant-induced remission of depression

BACKGROUND

Most hypotheses of the therapeutic mechanism of action of antidepressant drugs have focused on the role of the monoamines. We examined the effect of catecholamine depletion on antidepressant-induced remission.

METHOD

The tyrosine hydroxylase inhibitor alpha-methylparatyrosine and the antihistamine diphenhydramine hydrochloride were administered, during separate test sessions, to depressed patients in remission maintained with either norepinephrine reuptake inhibitors (desipramine [n = 7] or mazindol [n = 2]) or serotonin reuptake inhibitors (fluoxetine hydrochloride [n = 9] or sertraline hydrochloride [n = 1]). Because of considerable sedation associated with alpha-methylparatyrosine testing, diphenhydramine was used as an active control rather than an inactive placebo. The effects of alpha-methylparatyrosine and diphenhydramine on depression, anxiety, and plasma catecholamine metabolites were assessed.

RESULTS

alpha-Methylparatyrosine produced similar significant decreases in plasma 3-methoxy-4-hydroxyphenylethyleneglycol and homovanillic acid levels in the treatment groups. alpha-Methylparatyrosine produced a robust increase in depressive symptoms on the Hamilton Depression Rating Scale, including depressed mood, decreased concentration, anhedonia, loss of interest, and feelings of worthlessness, helplessness, and hopelessness, in the desipramine-mazindol but not in the fluoxetine-sertraline group. Diphenhydramine had no effects on mood in either treatment group.

CONCLUSIONS

The therapeutic effects of norepinephrine reuptake inhibitors, but not serotonin reuptake inhibitors, are reversed by catecholamine depletion. Considered with previous reports that serotonin depletion produces depressive relapses in patients in remission maintained with serotonin reuptake inhibitors, but not norepinephrine reuptake inhibitors, these findings suggest that antidepressants may not work via a single monoamine-related mechanism.

Predictive validity of medical student choices of practice location

We compared University of Alabama medical students' 1980-1981 practice location and specialty preferences with actual practice locations and specialties in 1991 with the following results. (1) Primary care physicians were located mostly in small or large communities, whereas larger than expected numbers of subspecialists practiced in smaller cities. (2) Actual proportions in primary care and surgical subspecialties were less than in earlier preferences; more than expected chose nonsurgical subspecialties. (3) Large city practice locations showed an increase in 1991 at the expense of earlier preferences for medium-sized cities. We suggest that the shift of primary care physicians to larger cities reflects concerns about the financial viability of small town practice, coupled with greater earnings in affluent suburbs. Excess numbers of subspecialists in smaller locations may be due to a perceived oversupply of subspecialists in larger cities.

Serotonin and the neurobiology of depression. Effects of tryptophan depletion in drug-free depressed patients

OBJECTIVE

To investigate the effects of tryptophan depletion in untreated depressed patients. Rapid dietary depletion of the precursor of serotonin synthesis, tryptophan, causes a transient return of depression in 67% of patients who have had a therapeutic antidepressant response.

METHOD

Forty-three untreated depressed patients underwent tryptophan depletion in a double-blind, placebo-controlled cross-over study. After testing, they received open sequential antidepressant treatment.

RESULTS

Mood did not change when tryptophan was depleted but did change on the day after the depletion test. Relative to the control test, 37% of the patients had 10-point or greater decrease in Hamilton Depression Rating Scale (Ham-D) score, while 23% had a 10-point or greater increase in Ham-D score on the day after the tryptophan depletion test. Change in mood was correlated to treatment response after testing. Patients whose condition worsened proved to be highly refractory to treatment while those who showed improvement were more likely to respond.

CONCLUSIONS

That tryptophan depletion did not rapidly worsen depression argues that serotonin function is not linearly related to the level of depression and if reduced serotonin function does cause depression, then it is either as predisposing factor or due to a postsynaptic deficit in the utilization of serotonin.

The use of tryptophan depletion to evaluate central serotonin function in depression and other neuropsychiatric disorders

The results from these and other studies provide an opportunity to critically re-examine the role of brain monoamine function in the pathophysiology of depression and the mechanism of action of antidepressant drugs. The following observations are most salient: 1. Tryptophan depletion, which reduces brain serotonin function, reverses the therapeutic effects of specific serotonin reuptake inhibitors (SSRIs) but not drugs which potently inhibit noradrenaline reuptake. In contrast, depletion of noradrenaline and dopamine, as a consequence of AMPT administration, reverses the remission induced by noradrenaline (desipramine) and dopamine (mazindol) reuptake inhibitors, but not SSRIs. These data suggest that the efficacy of antidepressant drugs may not be due to a common mechanism involving a single monoamine system. SSRIs and noradrenaline reuptake inhibitors may work via primary actions on serotonin and noradrenaline function, respectively. Alternatively, these two classes of antidepressant drugs may exert their therapeutic properties by affecting the function of an, as yet, unknown neuronal system that is regulated by these monoamine systems; 2. In both drug-free depressed patients and healthy subjects, tryptophan depletion and AMPT do not produce marked alterations in depressed mood. These results suggest that alterations in serotonin, dopamine, and noradrenaline systems may not reflect the primary pathology causing depressive illness. An alternative explanation is that in depressed patients these systems are maximally dysfunctional such that further manipulations do not worsen depressive systems. 3. Clinical experience and the results from several controlled studies indicate that the efficacy of SSRIs and noradrenaline inhibiting drugs are approximately equal.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical treatment of an aggressive metastasized eccrine poroma

We report the successful surgical treatment of a 24-year-old male with an aggressive metastasized eccrine poroma. The primary lesion was on the left plantar surface and resembled a pyogenic granuloma. Two months after we excised this lesion, the patient presented with a mass on the left groin, apparently a metastatic occurrence related to the tumor. We performed a radical lymph node dissection with no adjunctive treatment. Five years later, the patient is apparently free of any related disease.

Acute tryptophan depletion: a method of studying antidepressant action

Serotonin (5-HT) has been implicated in the pathophysiology of depressive syndromes and in the mechanism of antidepressant drug action. Rapid dietary depletion of tryptophan (TRP) provides a paradigm for studying the role of 5-HT in depressed patients. Drug-free depressed patients do not show mood changes during TRP depletion but about one third have a clinically apparent, transient improvement in mood on return to normal TRP intake. Depressed patients in clinical remission after 6 to 8 weeks of antidepressant therapy experience a transient depressive relapse during acute TRP depletion. The significance of these findings will be discussed. Tryptophan depletion in other psychiatric syndromes will also be reviewed.

Presuicide attempt communications between parasuicides and consulted caregivers

A high percentage of parasuicides visit professional caregivers prior to the attempted suicide. The content or outcome of these consultations is unknown. We interviewed hospitalized attempters and the professional caregivers they identified as having been consulted prior to their attempts. About half of these patients directly disclosed suicidal symptoms or intentions, especially to mental health professionals. These professionals more often inquired about suicidal ideations than did nonpsychiatric physicians. However, few caregivers noted suicidal thinking or probed suicidal symptoms. The data suggest that professional caregivers and especially nonpsychiatric physicians should be more sensitive and responsive to the signs and symptoms of suicidality.

"Supercharging" the rectus abdominis muscle to provide a single flap for cover of large mediastinal wound defects

Mediastinitis continues to be a devastating complication of open heart surgery. Supercharging the rectus abdominis muscle through revascularisation of the deep inferior epigastric vessels in the neck adds another safety factor in the management of these difficult problems. Large mediastinal wound defects that would usually require more than one muscle for cover can be covered adequately with this technique. Viability of the entire rectus abdominis is assured and permits use in its entirety. Details of the technique are presented as well as a review of the reconstructive options for mediastinal wound infections.

Comparison of hypertension prevalence and control in 5,237 rural and urban Alabama residents

Selected urban and rural Alabama populations were compared by age, sex, and race on the prevalence of hypertension and uncontrolled hypertension and the percentage of treated hypertensives with controlled blood pressure. We found the following results: (1) Rural women had a significantly higher prevalence of hypertension than urban women. (2) The prevalence of uncontrolled hypertension was significantly higher for urban white men than for their rural counterparts. (3) The prevalence of uncontrolled hypertension was significantly higher for rural black women aged 30 to 39 than for the same age group of urban black women. (4) Rural dwellers generally had much better blood pressure control than urban, though this was not manifested evenly across groups. Statistically significant differences were found for white men and women of all ages combined and in three of four age groups. Reasons for the rural-urban differences are unclear, but the rural area surveyed was served by nurse practitioner clinics that strongly emphasized patient education.

Flow cytometry evaluation of testicular and sperm cells obtained from bulls implanted with zeranol

Flow cytometry of testicular and sperm cells was used to evaluate effects of pre-weaning zeranol implants on spermatogenesis. Forty five Angus-Simmental bulls were randomly assigned to three treatment groups of 15 bulls each: no implant, one implant at 30 d of age and two implants, one at 30 and the second at 120 d of age. Prior to slaughter at approximately 15 mo, semen was collected from 30 bulls, 10 of each group. Following slaughter, testes were weighed, and testicular biopsies and vas deferens sperm obtained from the same 30 bulls. Testicular and sperm cells were stained with acridine orange and measured by flow cytometry. Proportions of testicular haploid, diploid and tetraploid cells were determined by relative amounts of green (DNA) and red (RNA) fluorescence. Treatment of sperm at low pH prior to acridine orange staining potentially induces partial denaturation of DNA, detectable by the metachromatic shift from green (native DNA) to red (single-stranded DNA) fluorescence. The effect of this shift was quantified by alpha-t [alpha t = red/red + green) fluorescence]. Nonimplanted bulls had heavier (P less than .01) testicular weights than treated bulls. The proportion of haploid cells was greater (P less than .02) and diploid cells less (P less than .03) in testes of nonimplanted bulls. Sperm from implanted bulls had altered chromatin structure, indicated by higher (P less than .05) alpha t values. Flow cytometry is an effective means for detecting changes in testicular cell subpopulations and chromatin structure of sperm.

Ureteral involvement secondary to diverticulitis of the colon

Ureteral involvement in instances of diverticulitis of the colon is quite unusual. The left ureter is more commonly involved but right sided and bilateral instances have been reported. There are three types of involvement: fistula, stricture and compression, the latter being the most frequent. Roentgenographic characteristics and the effects of various treatment modalities on the affected ureter are presented herein.

Lymphocyte subpopulations infiltrating squamous carcinomas of the head and neck: correlations with extent of tumor and prognosis

Because little is known about the mechanisms involved in local tumor-host immune reactions in squamous carcinoma of the head and neck, a study was undertaken to better characterize the types of immune cells present at the local tumor site and determine their relationship to tumor extent, systemic cellular immune parameters, and clinical outcome. In 40 untreated patients, lymphocyte subsets (LS) at the tumor-host interface were quantitated immunohistologically from serial sections of frozen tumor specimens and correlated with concurrently measured peripheral LS levels and in vitro lymphocyte reactivity to phytohemagglutinin (PHA). The majority of infiltrating lymphocytes were T cells with rare B or Leu 7 cells. Proportions of T4 and T8 were similar in peritumor stroma; however, T8 cells predominated tumor parenchyma. Stromal and parenchymal infiltration by LS were not related to peripheral blood LS levels, lymphocyte reactivity, or tumor site. However, parenchymal T11 and T4 cell infiltration was less in advanced primary tumors (T3, T4) than in early tumors (T1, T2) (P = 0.01, P = 0.067, respectively), as was peripheral lymphocyte reactivity to PHA (P = 0.013). Short-term disease-free interval and actuarial survival differed significantly--according to parenchymal T11 and T4 cell infiltration--and were not related to T8, Leu 7, and B-cell infiltration. The findings extend prior studies of lymphocytic infiltration in head and neck cancer and demonstrate the potential importance of differences in tumor stromal and parenchymal infiltration. Together with recent evidence that T4 cells are critical for lymphokine production and for the proliferation of cytotoxic effector cells, the current results suggest that T4 cells play a critical role in the local immune response in squamous carcinoma of the head and neck.

Modulation of complement fixation and the phlogistic capacity of group A, B, and D streptococci by human lysozyme acting on their cell walls

Streptococci and streptococcal cell wall fragments induce arthritis in rats, with the severity and duration depending on the capacity of the cells or cell fragments to resist degradation by tissue enzymes. Their phlogogenic effects are apparently related to their ability to activate the alternate complement pathway (ACP). The in vitro activation of the ACP by lysozyme-treated cells and cell walls of group A, B, and D streptococci suggests that both rat and human lysozyme can modulate this activity, i.e., increasing it, decreasing it, or doing both in that order. The effects of the lysozymes also correlated with the degree to which they can unmask the aminosugar-reducing groups detectable in a given amount of cell wall, which suggests that partial depolymerization of the cell wall is critical for ACP activation. The effects of mutanolysin and C phage lysin on ACP activation were found to be correlated with their action on streptococcal cell walls. Neuraminidase had relatively little effect on ACP activation by most streptococcal strains tested. We conclude that the participation of tissue enzymes, including but not necessarily limited to lysozyme, is an important determinant for the clinical arthritis induced by group A, B, or D streptococci. Experimental arthritis induced in rats with whole (or disrupted) streptococci may depend both on the capacities of the cell walls to activate the ACP and on the capacities of the host tissue enzymes to modulate this activation. Great severity and long durations of the disease were determined by the capacity of the enzymes to degrade cell wall antigens to a degree sufficient to ensure efficient activation of the ACP without completely degrading the material so that it no longer activates complement. In this model, the limited resistance of group B peptidoglycan to lysozyme was a critical pathogenic factor.

Plasma and urine levels of flumequine and 7-hydroxyflumequine following single and multiple oral dosing

Plasma and urine concentrations of flumequine and its microbiologically active metabolite, 7-hydroxyflumequine, were determined in healthy subjects following single oral doses of 400, 800, and 1200 mg of flumequine, and following multiple oral doses of 800 mg given four-times daily. After administration of the single oral doses, antimicrobial levels in plasma and urine were rapidly attained, were proportional to the dose given, and were maintained for 12 to 24 h. The multiple dosage regimen yielded antimicrobial levels in both plasma and urine that were several-fold higher than the levels required to inhibit the growth of susceptible bacteria. Following both the single and multiple dose regimens, the plasma elimination half-life of flumequine was about 7h. The excretion of 7-hydroxyflumequine in the urine contributed significantly to the antimicrobial activity.

Optimization versus response-strength accounts of behavior

Pigeons were run in both single-key and concurrent-key experiments in which, over most of the range of response rates, an increase in response rate gave rise to a continuous decrease in reinforcement rate. In spite of the fact that a low response rate would have produced a high reinforcement rate, all birds responded at relatively high rates, thus keeping reinforcement rates substantially below the maximum possible. In the concurrent-key experiment, in addition to responding at relatively high rates, the birds' ratios of responses approximately matched the corresponding ratios of obtained reinforcers. The results are inconsistent with most theories of optimal performance, which assume that organisms behave in ways that either maximize reinforcement value or minimize deviations from a free-behavior point. On the other hand, the results are consistent with the assumption that reinforcement strengthens the tendency to respond.

An analysis of the effects of suicide prevention facilities on suicide rates in the United States

Since the 1960s, there has been a massive effort to reduce suicide mortality in the United States through prevention centers which invite suicidal persons to phone for supportive services. In spite of virtually total lack of evidence concerning the efficacy of these services, they proliferated until, by 1973, nearly every metropolitan area in the United States had at least one. Suicide rates increased slightly throughout this time. We studied 1968 through 1973, the years of greatest growth of suicide prevention facilities, comparing suicide rates in counties that added these centers with counties that did not do so. An association of centers with the reduction of suicides in young white females emerged. This finding was replicated on a different set of counties for a different time span. The results are discussed in light of the fact that this group constitutes the major clients of these centers.

Granulomatous prostatitis. Special reference to radiologic findings

Cystourethrography was performed in 2 patients with nonspecific, noneosinophilic granulomatous prostatitis. Lengthening of the prostatic urethra was noted essentially in the inframontane portion, thus differentiating it from benign prostatic hypertrophy. The widening in the prostatic urethra differentiates it from carcinoma of the prostate.