Motor responses to food of the ileum, proximal colon, and distal colon of healthy humans

Intraluminal pressures and motility indexes were recorded from ileum, ascending colon, rectosigmoid colon, and rectum of 6 healthy men. Three different test meals were eaten at 5-hour intervals. During fasting, migrating motor complexes were identified in the ileum. In ascending colon, irregular, isolated peaks of pressure were common; when bursts of continuous activity occurred, their predominant frequency was 6/min. Regular contractile activity occurred in distal colon at a frequency of 2.5-3.5/min. although 3 subjects also demonstrated rates of 7/min. There were both synchronous and independent contractions of the rectosigmoid and rectum, and no temporal relationship was obvious between motor activities of ascending and distal colons. When the preprandial hour contained no migrating motor complex, all meals increased the ileal motility index by 50%. The motility index of ascending and rectosigmoid colons were enhanced by solid meals, but not by meals containing amino acids. We conclude that motor patterns in the colon vary regionally, both fasting and after food. Results obtained at one site of the large intestine should not be extrapolated to others.

Effect of physiological manipulations on the chemotherapy of experimentally induced renal infection

The belief that a favorable physiological milieu in the urinary tract may augment the effectiveness of antimicrobial agents used to treat urinary tract infections was examined by using an experimental model of Escherichia coli-induced renal infection in rats. The effect of manipulating urinary pH and flow on the antimicrobial activities of gentamicin, carbenicillin, ampicillin, nitrofurantoin and co-trimoxazole was assessed. In addition, a potential synergistic effect of the sequential administration of gentamicin and cephalothin in the eradication of renal infection was investigated. Although significant physiological alterations were achieved, these did not affect the efficacy of the antimicrobial agents studied, and therapeutic failures were common.

Parental characteristics and interactional dysfunction in families with child behavior problems: a preliminary investigation

Thirty-six families with a preteenage behavior problem child were assessed on measures of marital discord, parental psychopathology, and three parental cognitive factors: knowledge of behavioral principles, tolerance for child deviancy, and expectations regarding their child's behavior. Nine nonproblem families with demographic characteristics similar to the problem families were also assessed. Correlational analyses across all families revealed a strong association between marital discord and the parental index of child behavior problems. While a number of significant associations were discovered between the various measures of marital discord, parental psychopathology, and parental cognitive factors, no other measure besides marital discord was associated with parental perception of child behavior problems. The nonproblem families and 15 of the problem families also participated in home observations obtained through random audio recordings during high interaction periods. These observational data indicated a significant relationship between parental perception of child behavior problems and parental negative behavior toward the child, but no significant relationship between parental perception of child behavior problems and child behavior, even when child behavior was weighted by parents' reactions to that behavior. Through sequential analysis, several contingent relations between parent and child behavior were discovered. Findings are discussed in relation to family systems theory.

Evaluation of a residency training program in behavioral pediatrics

The impact of behavioral training upon first-year residents was evaluated by assessing attitudes with regard to 15 clinical "entities," including behavioral disorders, physical disorders, and "mixed" disorders. Each entity was rated at four times: beginning of the year, start of the behavioral rotation, end of the rotation, and end of the year. Multiple-choice questions were also included to assess knowledge regarding behavioral pediatrics. Data were collected from 37 residents, from 1977 to 1980. For behavioral disorders and mixed disorders, residents' self-reported competence increased with regard to diagnosis, management, advising parents, and knowledge of resources. Further, the greatest change occurred during the 2-month rotation. In contrast, change in perceived competence for physical disorders was not specific to the rotation but, rather, increased evenly over the year. Ratings of faculty and housestaff interest remained constant across testing points, and residents' "desire to learn more" and prediction of "future relevance" showed a slight decrease over time, for all disorders. Knowledge regarding behavioral pediatrics increased significantly from the beginning of the year to the start of the rotation, and also during the rotation. These data demonstrate that changes in residents' perceived competence are directly related to their rotation experience, and suggest that behavioral issues can be introduced successfully during the first year of residency training.

Screening for pharyngeal gonorrhea in the urban teenager

A retrospective chart review assessed the occurrence of pharyngeal gonorrhea among 546 teenagers who attended a general adolescent clinic and were cultured for gonorrhea; they had been routinely cultured at three sites (cervix/urethra, rectum, and pharynx) regardless of their history of sexual practice. No record of specific sexual practice was available. This population was predominantly urban, black, and female; the age range was 11 to 22 years (mean = 16.5). The overall occurrence of gonorrhea was 14.7% (80/546). Pharyngeal gonorrhea was detected in 2.7% of the study population, representing 12 females and three males. Of the 80 patients with gonorrhea, 15% had only pharyngeal gonorrhea. History was available for 13/15 patients none had pharyngeal symptoms. Approximately half were detected by routine screening at a family planning visit; the remainder had complaints related to sexually transmitted disease. The occurrence of pharyngeal gonorrhea is sufficiently high to merit study of the indications for pharyngeal culture of teenaged patients. Given the potential for disseminated infection and absence of information regarding the reliability of self-report, it currently appears appropriate to culture adolescents routinely for pharyngeal gonorrhea, regardless of stated sexual practice, whenever genital cultures are collected.

Variability of motility of the ileum and jejunum in healthy humans

Motor patterns of the distal small bowel were defined in healthy humans, using a multilumen polyvinyl tube, passed by mouth in 11 healthy subjects. Five recording sites, spanning 100 cm of tube and featuring a nitrogen hydraulic infusion system, were used to obtain records during 6 h of fasting and 6 or more hours after ingestion of a 600-kcal liquid test meal. The loci of recordings were designated as jejunal, ileal, or terminal ileal, as judged by the length of tube within the intestine and by fluoroscopy. During fasting, the migrating motor complex was present in all subjects and at all levels of the small intestine, but it could not be traced into the colon. Interdigestive cycles were defined primarily by the presence of an "activity front" (phase 3 of the migrating motor complex). Ninety-six migrating motor complexes occurred each 97 min (grand mean for all loci), but intervals between individual activity fronts varied markedly (15-195 min), in contrast to what is reported in other species. The velocity of aboral migration was 4.7 +/- 1.8, 1.3 +/- 0.4, and 0.9 +/- 0.2 cm . min-1 (mean +/- SD) in jejunal, ileal, and terminal ileal, respectively. Rates of continuous, rhythmic contractions during activity fronts declined distally: 12.5 to 10.5 (jejunal), 10.9 to 9.3 (ileal), and 10.0 to 8.6 cycle/min (terminal ileal), respectively. In individual subjects, maximum rates of contraction and velocities of migration always declined distally, but the duration of activity fronts was unrelated to the level of recording. Food interrupted the fasting cycles of motility for periods ranging from 2.75 to greater than 10 h. The transition from the fasting to the fed pattern was prompt and the postprandial motility was that of irregular bursts of contractions interspersed with transient quiescence. These studied demonstrate that the migrating motor complex occurs throughout the human small intestine, and that inter- and intraindividual variations are marked; food disrupts the complex for variable periods. These variations must be considered when abnormalities are being sought in disease states.

Relationship of motility to flow of contents in the human small intestine

To measure simultaneously motility and flow of intestinal contents, a multilumen polyvinyl tube was passed by mouth in 10 healthy volunteers. Motility was recorded at five sites, spanning 100 cm of tube, to allow recognition of migrating motor complexes during fasting and during their disruption by food. Loci were designated as jejunal, ileal, and terminal ileal, as judged by length of tube in the intestine and by fluoroscopy. Flow of intestinal contents was measured by indicator (phenolsulfonphthalein) dilution over a 20-cm segment; flow was related to motility at the perfusion site. A liquid test meal of 400 ml and 600 kcal, containing polyethylene glycol 4000, was eaten after 6 h of fasting. During fasting, flow of intestinal contents was intermittent at all levels and varied with the presence of or absence of the activity front ("phase 3" of the migrating motor complex). The activity-front periods contributed 50% of total flow, but occupied less than one-third of the total recording time. Flow corrected for time was significantly greater with the presence of activity front than with phases 1 or 2 of the migrating motor complex (p less than 0.001). In addition, of 45 increments in flow of greater than 0.75 ml . min-1, the majority (82%) were associated with an activity front. The flow rate increased promptly after a meal and fluctuated markedly during the postprandial period in most studies. By the time migrating motor complex had returned, more than 90% of meal marker (polyethylene glycol) was accounted for in intestinal aspirates. In contrast, only 56%-73% of marker was recovered postprandially in those studies in which the migrating motor complex had not returned by the time the study was terminated. Thus, flow of intestinal content is largely intermittent during fasting, peaks of flow being associated with passage of the activity front of the migrating motor complex; on the other hand, half the fasting flow is unassociated with the activity front. Reappearance of the migrating motor complex at any level after a liquid test meal signals clearing of the liquid meal from the more proximal intestine.

An asymmetrical model of the airways of the dog lung

A resin cast of the bronchial tree of a dog was studied down to branches of 0.5-mm diameter. The branches were ordered, and the number of branches, mean diameter, and mean length of branches in each order were determined. The model was developed from these data with the property that delta, the difference in order between the two daughter branches at a bifurcation, is identical for all parent branches of a given order. This property facilitates the use of the model for the calculation of physiological variables such as input impedance (Fredberg and Hoenig, ASME J. Biomech. Eng. 100: 57-66, 1978), and the comparison of such results with those obtained from symmetrical models (Sidell and Fredberg, ASME J. Biomech. Eng. 100: 131-138, 1978).

Teenagers' preferences regarding the presence of family members, peers, and chaperones during examination of genitalia

During physical examination that include the genitalia, teenagers are typically separated from their parents and females are provided with a chaperone. To assess teenagers' attitudes regarding this practice, 140 females and 60 males awaiting treatment in a general adolescent clinic were asked their opinion about a physical examination that include the genitalia. Teenagers indicated whether they would want to be accompanied during the examination, and by whom, as a function of the hypothetical clinical situation that varied the sex and familiarity of the physician. Choices reflected teenagers' age and sex, rather than physician characteristics. Young males and females strongly preferred to be accompanied, generally by a family member. With increasing age, males preferred to be alone with the physician whereas females preferred to be accompanied. Regardless of sex and age, virtually none chose the company of peers. Despite strong development differences, however, there also were pronounced individual differences among teenagers of the same age. Our results suggest that service delivery be adapted to the particular preference expressed by individual teenagers. Needs assessment for adolescent programs may best be achieved by conducting similar surveys in local clinical settings.

What's the difference? Pediatric residents and their inaccurate concepts regarding statistics

Two multiple-choice questions were designed to assess pediatric knowledge of two statistical concepts: (1) correlation and (2) probability values for statistical significance. One question was administered to 684 residents from 24 major pediatric training programs; this response rate represented 84% of all residents in these programs (PL-1, PL-2, and PL-3 years). In 20 of these programs, the second question was administered to 437 residents, representing a 79% response rate. Less than 20% of the residents responded correctly to the first question, and approximately half chose correctly on the second question. Further, no trend toward improvement was apparent with additional years of residency training. This limited knowledge of statistical concepts suggests that pediatricians are not well equipped to evaluate the scientific merit of research reported in pediatric journals.

Pyelonephritis: the relationship between infection, renal scarring, and antimicrobial therapy

We studied the relationship between infection, renal scarring, and antimicrobial therapy in pyelonephritis by an experimental model of the disease. Our specific concern was to identify those aspects of the acute phase of infection associated with the induction of the inflammatory response. Our hypothesis was that the degree of the inflammatory response and the extent of the subsequent lesion in the kidney depended on the rate at which a critical number of microorganisms was reached in the kidney. We proposed that the rapid increase in bacterial numbers in the kidney was the stimulus initiating the inflammatory response and not the total number of microorganisms in the kidney. In the experimental investigation, we treated animals with induced renal infection at varying intervals after the establishment of infection, and we determined the effect of antimicrobial therapy on the bacteriologic, gross, and histopathologic features of the disease. The early events relating to the bacterial invasion of the kidney were important determinants but the hypothesis needed extending to account for the fact that antimicrobial agents, administered after bacterial numbers had reached a plateau, still reduced markedly the damage to the kidney. Two factors seem to be involved in the genesis of the pyelonephritic lesion. The first is the rate of acquisition of a bacterial population by a previously sterile organ, but an additional and important component is the total number of microorganisms in the kidney up to 4 days after challenge. Clinically, the results are relevant in that they demonstrate that renal scarring can be prevented or significantly reduced by prompt antimicrobial therapy.

Relative levels of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) in some N2 fixing bacteria during derepression and repression of nitrogenase

Addition of ammonium to N2 fixing cultures of Azotobacter vinelandii, Klebsiella pneumoniae and Clostridium pasteurianum rapidly reduced the intracellular levels of guanosine 5'-diphosphate 3'-diphosphate (ppGpp) by 70-90%. This change might reflect a regulatory role of ppGpp in nitrogen metabolism.

Improved survival of ventilated neonates with modern intensive care

The records of 909 infants who required mechanical ventilation over a 42-month period were reviewed; 68.3% of the infants survived. The highest survival rate was in infants with persistent fetal circulation and hyaline membrane disease, and the lowest in infants with congenital anomalies and miscellaneous diseases. The survival rate for each year of the 3 1/2-year study increased from the previous year. There was also a dramatic increase in the survival rate in infants with a birth weight greater than 1,250 gm.

Children's Perceptions of Health and Disease

One aspect of preventive medicine is public education. Though primary care physicians educate their patients individually, their involvement in the school system has been limited.A study of children's attitudes toward health was undertaken to define a basis upon which a preventive education program could build. It was found that children are curious about the functioning of their bodies, aware of the importance of exercise and nutrition, and adamantly opposed to smoking. An effective education program should combine factual teaching with the "selling" of a healthy lifestyle to reinforce pre-existing interests and attitudes.

Defined transversion mutations at a specific position in DNA using synthetic oligodeoxyribonucleotides as mutagens

The oligodeoxyribonucleotides, pCCCAGCCTCAA, which is complementary to nucleotides 5274--4284 of bacteriophage phi X174 viral DNA , and pCCCAGCCTAAA, which corresponds to the same sequence with a C leads to A change at the ninth nucleotide, were synthesized enzymatically. The second of these oligonucleotides was used as a primer for E. coli DNA polymerase I, from which the 5'-exonculease has been removed by proteolysis (Klenow enzyme), on wild-type phi X174 viral DNA template. After ligation, this yielded closed circular heteroduplex DNA with a G, A mismatch at nucleotide 5276. Transfection of E. coli spheroplasts with the heteroduplex DNA produced phage mutated at this nucleotide (G leads to T in the viral DNA) with high efficiency (13%). The mutant DNA, which corresponds to the gene B mutant am16, was reverted (T leads to G) by the wild type oligonucleotide with an efficiency of 19%. The nucleotide changes were established by sequence determination of the mutated viral DNA using the enzymatic terminator method. The production of specific transversion mutations, together with a previous demonstration of specific transition mutations (1), established that short enzymatically synthesized oligodeoxyribonucleotides can be used to induce any class of single nucleotide replacement with high efficiency and thus provide a powerful tool for specific genetic manipulations in circular genomes like that of phi X174.

Mutagenesis at a specific position in a DNA sequence

Predefined changes in a known DNA sequence were introduced by a general method. Oligodeoxyribonucleotides complementary to positions 582 to 593 of the viral DNA strand of the bacteriophage phiX174 am3 mutant (pGTATCCTACAAA), and to the wild type sequence in this region (pGTATCCTACAAA), were synthesized and used as specific mutagens. Each of these oligonucleotides was incorporated into a complete circular complementary strand when used as primer on a genetically heterologous viral strand template, by the combined action of subtilisin-treated Escherichia coli DNA polymerase I and T4 DNA ligase. Incomplete duplexes were removed or were inactivated by nuclease S1 and the products were used to transfect spheroplasts of E. coli. Both oligonucleotides induced specific mutations at high efficiency when used with heterologous template (15% mutants among progeny phage). The am phages isolated by this procedure are phenotypically gene E mutants, and contain A at position 587 of the viral strand. They thus appear identical with am3 and provide evidence that the change G leads to A at position 587 is sufficient to produce a defective E function. Since the template for the induction of am mutants carried another genetic marker (sB1), the strains carrying the induced mutations have the new genotype am3 sB1. It should be possible to introduce the am3 mutation into any known mutant strain of phi174 using this same oligonucleotide. Both possible transition mutations were induced in these experiments. In principle, the method could also induce transversions, insertions, and deletions. The method should be applicable to other circular DNAs of similar size, for example recombinant DNA plasmids.

Spontaneous activities of female versus male newborns

This study explored potential sex differences in all activity spontaneously emitted by newborns. 2 groups of full-term infants (14 uncircumcised males, 15 females), equally distributed along several physical and demographic variables, served as subjects. Each newborn was observed for a total of 8 hours during the 2 days following birth. Observational procedures were stringently controlled and interobserver reliability ranged from .84 to .98. Results showed higher levels of wakefulness, facial grimacing, and low-intensity motor activity for males. Of marginal significance, both low-intensity and high-intensity oral activity was higher for males. In addition, a marginally significant interaction effect (sex X interfeeding interval X day) was found for high-intensity oral activity (crying). Independent of sex, high-intensity activity increased in the evening and over an interfeeding period, and low-intensity oral activity increased over days. The pattern of results indicates that even uncircumcised males may be slightly more irritable than females, and thus more active. Potential implications of these findings are considered.

Complement-mediated immune mechanisms in renal infection. II. Effect of decomplementation

Animals were depleted of complement using cobra venom factor and the influence of complement depletion on the course of renal infection was studied. Complement depletion markedly increased the susceptibility of renal tissue to a challenge with an E. coli strain sensitive to the bactericidal activity of normal serum, but did not influence the outcome of a challenge with a serum-resistant strain of E. coli. These observations are consistent with the hypothesis that complement-mediated host immune mechanisms do play a role in the biology of renal infection and are an important component of the host's immune response in pyelonephritis.

Blur: a sufficient accommodative stimulus

Experiments under a variety of open and closed loop feedback configurations demonstrate that accommodative responses to target blur are equivalent to those to defocus blur; this supports blur as the 'sufficient' neurological stimulus to accommodations. The hunting action of accommodation compensates for the even error aspect of blur and also adaptively minimizes any close loop error components while finally accepting open loop components.

Neuro-optometry: an evolving specialty clinic

Neuro-optometry is evolving as an optometric clinical specialty focusing on neurological dysfunctions of the visual system. Initially, we focused upon abnormalities of ocular movements, and our investigations have now broadened to include static and dynamic measurements of eye movements, accommodation, and the pupil. We feel the clinic serves three fundamental purposes: (1) to provide service to the patient, (2) to perform clinical research, and (3) to broaden the scope of the students' clinical experience. Operation of the clinic, technical methods of measurement, the testing protocol, and examples of interesting clinical recordings are described.

Luminal distension as a possible consequence of experimental intestinal perfusion

In an experimental jejunal perfusion study, distress in healthy subjects occurred during eight out of 16 perfusions in which intestinal secretion was provoked. Calculation demonstrates the volumetric consequences of inadequate recovery of secretory perfusates, and analysis of the perfusion studies shows that distress was significantly associated with poor recovery of the perfusate. These observations are pertinent to increasing interest in the phenomenon of intestinal fluid secretion.

Employing paraprofessional teachers in a group language training program for severely and profoundly retarded children

A study was conducted to evaluate the effectiveness of a newly developed language training program particularly suited for the severely retarded. Designed for use with non-professional staff acting as teachers, the program contains (1) a simplified introduction to operant and modeling procedures, (2) detailed lesson plans, (3) necessary materials, and (4) instructions for testing and evaluation. Institutionalized children classified as severely and profoundly retarded were pretested and assigned to four groups, based on pretest scores. Pairs of children were matched within each group according to pretest performance, language equivalence scores, mental classification, age, sex, race, and behavior problems. One member of each matched pair was then randomly designated an experimental or control child. The experimental groups received 2 mo. of language training (each group comprising one class), with two psychiatric aides conducting all activities. As training was completed, all children were posttested. Comparison of pre- and posttest performances indicated clear treatment effects, demonstrating the potential for wide-spread institutional use of such programs.

Error-detection and correction latencies as a function of S-R compatibility

In choice-response tasks employing correction-procedure, error-correcting responses are typically found to be faster than equivalent correct responses. An experiment was made to compare error-correction RT under conditions of good and poor S-R compatibility in a two-choice task. After practice, variations in S-R compatibility producing significant variations in mean correct RT nevertheless have no effect on error-correction time. The contrast between this result, and one previously reported (Burns, 1965) leads to a re-discussion of the processes of error detection and correction.