p53 expression in lymphatic malignancies.

To investigate the expression of p53 protein in malignant and benign lymphoid tissues. Tissue from 42 non-Hodgkin's lymphomas, 10 Hodgkin's lymphomas, three atypical hyperplasias and five benign reactive hyperplasias was studied immunohistochemically for the expression of p53 protein. Of the 42 non-Hodgkin's lymphomas, 13 (31%) were positive for p53 in some of the tumour cells. In two cases the proportion of positive cells was more than 10% and in four cases it was between 1-5%. These six cases consisted of three Burkitt's lymphomas, one immunoblastic lymphoma, one centroblastic diffuse lymphoma and one angioimmunoblastic lymphoma. In seven cases the proportion of p53 positive tumour cells was less than 1%. These cases comprised three centroblastic diffuse, three centroblastic polymorphic diffuse, and one angioimmunoblastic type lymphoma. In three out of 10 (30%) Hodgkin's lymphomas, a proportion of the Reed-Sternberg cells were p53 positive. One of these was a mixed cellular subtype and two nodular sclerosing subtypes. p53 protein was not expressed in the three atypical hyperplasias or the five benign reactive hyperplasias of the lymph nodes. The presence of p53 positivity in non-Hodgkin's and Hodgkin's lymphomas indicates that mutations of the p53 gene may play a part in the development of these tumours. The concentration of p53 positivity in high grade lymphomas suggests that p53 is involved in the transformation of low grade lymphomas to more aggressive types. Because no p53 positivity was observed in benign lesions of the lymph nodes, positive p53 immunohistochemical staining in a lymphoid lesion suggests malignancy.


Intramammary lymph nodes.

To determine the prevalence and pathology of intramammary lymph nodes in breast specimens. All breast specimens examined by a single pathologist over 70 months in a large teaching hospital were studied retrospectively. All the surgical pathology reports were reviewed. Relevant glass slides from cases in which intramammary lymph nodes were identified were also reexamined. Breast specimens (n = 682) were examined. Seven lymph nodes were found in five patients. The specimens comprised 533 biopsy specimens, 29 segmental resections, 22 reduction mammoplasties, 77 modified radical mastectomies and 20 gynecomastia mastectomies. No clinically relevant microscopical abnormalities were found in four lymph nodes and slight sinus histiocytosis was seen in two nodes. One node contained metastatic adenocarcinoma and benign glandular epithelial inclusions. Although rare, intramammary lymph nodes may be detected by careful gross examination of breast specimens even in the absence of clinical identification. They can occur in any quadrant of the breast and can display a variety of pathological conditions. Pathologists should be alert to the existence and potential importance of these lymph nodes.


Immunohistological study of distribution of gamma/delta lymphocytes after allogeneic bone marrow transplantation.

The distribution of T lymphocytes expressing the gamma/delta form of the T cell receptor was studied in the liver, intestine, and major lymphoid organs, after bone marrow transplantation (BMT), including cases of graft versus host disease (GvHD). The number of gamma/delta as a proportion of the total number of CD3 positive cells did not differ from that found in normal tissues; the higher percentage normally found in the intestinal epithelium and splenic red pulp was maintained. This, and the results of a previous study undertaken on the skin, provide no evidence that gamma/delta T cells have a particularly important role in T cell regeneration after marrow transplantation or in the pathogenesis of the epithelial lesions associated with GvHD.


Well differentiated (benign) papillary mesothelioma of the tunica vaginalis.

An unusual mesothelial lesion occurred in the tunica vaginalis of the testis. It conformed histologically and immunohistochemically to well differentiated papillary mesothelioma of the peritoneum. Its aetiology remains uncertain, but this lesion, more than likely, is innocuous. It is important to recognise this entity, which is not well documented in the tunica vaginalis, because it may be misdiagnosed as a malignant mesothelioma and the patient may be subjected to unnecessary treatment.


Mucous metaplasia of the pleura.

A case of mucous metaplasia of mesothelium in an 80 year old woman is described. Its cause is unknown, but it is important not to confuse it with secondary tumour.


Intradural bronchogenic cysts.

The pathological findings of an intradural and extramedullary cyst in the mid cervical spinal canal are described in a 55 year old woman who presented with a short history of pain and paraesthesia of the right arm. Intradural well defined solitary cystic lesions in the spinal canal are uncommon, their pathogenesis is poorly understood, and their nomenclature is confusing. In this case the cyst was a bronchogenic cyst; these are a rare form of such cysts and they are thought to be a malformation arising from a split notochordal syndrome and not a teratoma.


Pneumococcal endocarditis and disseminated infection.

A 61 year old woman presented with back pain and clinical signs of meningitis. Pleocytosis in the cerebrospinal fluid was found, but although Streptococcus pneumoniae was cultured from her blood it failed to grow from the cerebrospinal fluid. An echocardiogram detected vegetations on the mitral valve and a lesion at S1/S2 was demonstrated on a bone scan. Treatment for one month with benzylpenicillin (1200 mg four hourly) was successful for both the cardiac and neurological components of her infection, but her back pain only resolved after treatment was changed to clindamycin. The clinical presentation and metastatic spread of the S pneumoniae infection is much more commonly seen in the context of S aureus endocarditis. It is rare for the pneumococcus to be associated with endocarditis and when it is mortality is usually high. This case shows the metastatic potential of the organism and the requirement for appropriate antibiotics with regard not only to the sensitivity of the organism, but also for the site of infection.


Screening for Corynebacterium diphtheriae.

A throat swab from a 9 year old girl with pharyngitis yielded a non-toxigenic strain of Corynebacterium diphtheriae var mitis and Streptococcus group G. C pseudodiphtheriticum was isolated from the throats of two of her four brothers. In each case the isolate was sent to the reference laboratory before full identification. The growth was found to be mixed for one brother; the other isolate being a toxin producing C diphtheriae var gravis. The child was asymptomatic and the case proves that all colonial types on the Hoyles plate should be identified.


Chronic giardiasis of the stomach.

Two cases of chronic giardiasis of the stomach diagnosed from gastric mucosal biopsy specimens are reported. The first case was associated with an acute-on-chronic gastritis and Helicobacter-like organisms, and the second with an adenocarcinoma of the stomach. In both cases the trophozoites had been missed in earlier biopsy specimens. As far as is known this is the first report of giardiasis of the stomach.


Restrictive endocardial fibroelastosis in a neonate without other cardiac pathology.

A case is presented of constrictive endocardial fibroelastosis without other cardiac abnormality in a newborn infant who was treated successfully by orthotopic heart transplantation.


New rapid identification test for Clostridium difficile.

A set of five tests were developed and tested for their ability to confirm the identity of C difficile colonies within 30 minutes. The relevant substrates were incorporated into four filter paper squares attached to a plastic carrier (Diffstrip), five enzymes/products (prolyl aminopeptidase, galactosidase, leucine aminopeptidase, acid phosphatase and indole). The strips were inoculated, incubated for 20 minutes, and reagents added. 96.4% (212 of 220) strains of C difficile were immediately differentiated from 51 other Clostridium spp tested. The remaining 3.6% (eight of 220) of C difficile isolates produced a reaction pattern similar to some of the Clostridium sporogenes tested and required additional tests. None of the other Clostridium spp tested produced reaction patterns similar to C difficile. The Diffstrip allowed colonies of C difficile to be confirmed within 30 minutes for 96.4% of isolates, with less than 4% requiring any additional tests. No strains of C difficile were misidentified and no strains of other Clostridium spp tested were misidentified as C difficile.


Aeromonas spp as a potential cause of diarrhoea in children.

To determine the prevalence of Aeromonas spp in the faeces of children and the association with symptoms of gastroenteritis. Faecal specimens (n = 1026) were cultured for Aeromonas spp using three selective media and an enrichment broth at both 30 degrees C and 37 degrees C. The isolation of Aeromonas spp was correlated with symptoms of gastroenteritis, previous antibiotic use, and environmental temperature. Aeromonas spp (n = 28) from 26 (2.5%) patients were recovered. Bile salt, Irgasan, and brilliant green agar was the most efficient selective culture medium. Eleven of the patients had symptoms of gastroenteritis, usually mild diarrhoea of two to three days' duration, in the absence of other recognised enteropathogens. A caviae was a particularly frequent isolate (nine out of 11 cases) in symptomatic individuals. Only one out of seven Aeromonas spp recovered by enrichment culture alone was possibly associated with symptoms of gastroenteritis. There was a close correlation between the environmental temperature and isolation of Aeromonas spp. Aeromonas spp and particularly A caviae may cause gastroenteritis in children, most often during warmer months of the year. Culture for these potential enteropathogens could be confined to summer and autumn months. Bile salt, Irgasan, and brilliant green selective agar, but not alkaline peptone water enrichment, is an efficient culture medium for recovering possibly clinically important isolates.


Gastric giardiasis.

To assess the prevalence of gastric giardiasis in patients undergoing upper gastrointestinal endoscopy, and to define the clinicopathological correlates of gastric Giardia lamblia infection. Consecutive gastric biopsy specimens (n = 15,023) from 11,085 patients, taken at Feltre City Hospital (north eastern Italy) from January 1986 to December 1991, were histologically and immunocytochemically examined for the occurrence of G lamblia trophozoites. Three gastric biopsy specimens from patients harbouring G lamblia infection, who repeated endoscopy before treatment, were also examined electron microscopically. Forty one patients (0.37% of the population study) harboured gastric giardiasis. All patients underwent upper gastrointestinal endoscopy because of dyspepsia, epigastric pain, or abdominal distension. Only two patients had diarrhoea at the time of investigation. Giardiasis was clinically unsuspected in all cases, although the nine patients who also had duodenal biopsies performed had concomitant intestinal giardiasis. Gastric giardiasis was invariably associated with chronic atrophic gastritis. Intestinal metaplasia of the gastric mucosa and Helicobacter pylori infection were found in 32 and 37 of the 41 patients with gastric giardiasis, respectively. The invariable association of gastric giardiasis with chronic atrophic gastritis, most often showing intestinal metaplasia and H pylori infection, indicates that a decreased gastric acidity is a prerequisite for localisation of G lamblia to the gastric mucosa. Though its possible role as a gastric pathogen remains to be elucidated, these findings suggest that trophozoites should be carefully searched for when examining gastric biopsy specimens showing chronic atrophic gastritis.


Parasitology: United Kingdom National Quality Assessment Scheme.

To assess the results from parasitology laboratories taking part in a quality assessment scheme between 1986 and 1991; and to compare performance with repeat specimens. Quality assessment of blood parasitology, including tissue parasites (n = 444; 358 UK, 86 overseas), and faecal parasitology, including extra-intestinal parasites (n = 205; 141 UK, 64 overseas), was performed. Overall, the standard of performance was poor. A questionnaire distributed to participants showed that a wide range of methods was used, some of which were considered inadequate to achieve reliable results. Teaching material was distributed to participants from time to time in an attempt to improve standards. Since the closure of the IMLS fellowship course in 1972, fewer opportunities for specialised training in parasitology are available: more training is needed. Poor performance in the detection of malarial parasites is mainly attributable to incorrect speciation, misidentification, and lack of equipment such as an eyepiece graticule.


Solitary necrotic nodule of the liver: parasitic origin?

To report further cases of solitary necrotic nodule of the liver and to study its nature. Seven nodules were retrieved from 4000 necropsy and surgical liver specimens coming to light over the past five years. All of them satisfied the diagnostic criteria of solitary necrotic nodule: a solid lesion with a central necrotic core and a hyalinised fibrotic capsule containing elastic fibres. Their clinicopathological features were reviewed. The nodules were incidental findings at surgery or necropsy in four men and three women whose ages ranged from 48 to 79 years (mean 63.7 years). Four were found in the right lobe and three in the left. Six were subcapsular and only one deep in the parenchyma, with sizes ranging from 0.3-2.5 cm. Each of them was solitary, well demarcated, and round to oval with a firm, whitish rim and a core of yellowish white cheese-like to solid material. In addition to the basic architecture, there were a number of common and undescribed histological features: presence of varying numbers of small mural vessels with intimal fibrosis and obliteration, presence of cholesterol clefts and foamy cells among necrotic material, and sparsity of inflammatory cells. In the two cases where ghosts of degenerated cells and partially preserved liver reticulin pattern were noted, worms were identified, one being Clonorchis sinensis. The entity is believed to be a "burnt-out phase" of a variety of benign lesions. Parasitic infestation is another possible cause, and presence of ghosts of degenerate cells, partially preserved liver reticulin pattern, cholesterol clefts and foamy cells among necrotic material are auxiliary features pointing to such an aetiology. The variation in morphological fine details reflects both the lesion's diverse pathogenesis and the fact that it can be of varying duration.


Effects of chemotherapy on ultrastructure of oesophageal adenocarcinoma.

To compare and contrast the ultrastructural appearance of resected oesophageal adenocarcinomas treated with preoperative chemotherapy with that of non-treated resected controls; and to determine the usefulness of this method in the assessment of the effectiveness of the chemotherapeutic regimen. Ten resected oesophageal adenocarcinomas treated with preoperative chemotherapy--mitomycin-C, ifosfamide, and cisplatin (MIC)--were examined by transmission electron microscopy and their appearance compared with that of 13 concurrent untreated resected oesophageal adenocarcinomas. The treated adenocarcinomas showed cytotoxic damage although complete tumour eradication was not achieved. In all 10 treated cases a variable proportion of the neoplastic cells showed unusual degenerative and necrotic changes not seen in untreated cases. In the most affected carcinomas the stroma contained increased numbers of inflammatory cells. This ultrastructural method is useful for the assessment of the in vivo effect of MIC.


Histopathological and microanalytical study of zirconium dioxide and barium sulphate in bone cement.

To report the appearances of zirconium dioxide and barium sulphate in interface membranes, synovium, and other tissues around joint prostheses. Histological sections from 23 specimens were reviewed by light microscopy and polarisation. Scanning electron microscopy and x ray microanalysis were performed on routinely processed paraffin wax sections. Polyethylene, metals, and polymethylmethacrylate cement debris were easily recognisable. Almost all the cement remnants contained either zirconium dioxide or barium sulphate, confirmed by microanalysis. The contrast media had characteristic light microscopic appearances. Zirconium was identified in macrophages away from cement remnants. The presence of radiographic contrast media in tissues around prosthetic joints is common but not widely recognised.


Remodelling of subchondral bone in osteoarthritis: a histomorphometric study.

To determine whether remodelling of subchondral bone in osteoarthritis is related to anatomical and mechanical factors operating on the joint surface. Ten femoral heads were examined. Patients due to have the femoral head removed because of osteoarthritis were given a double tetracycline label before surgery. The specimens were divided in three roughly equal parts, corresponding to the medial, central (weight bearing), and lateral aspects of the femoral heads. Undecalcified methylmethacrylate embedded sections were prepared. The subchondral bone was assessed for appositional bone formation by ultraviolet light microscopy, for resorptive activity by osteoclast count, and for trabecular bone volume by semiautomatic computerised image analysis. Appositional bone rate was also correlated with the presence or absence of overlying cartilage. Bone density was reduced in the medial aspect of the femoral heads but there was no significant difference between the appositional bone rate or the resorptive activity in the three areas. Nor was there any correlation between appositional bone rate in the subchondral bone and the presence or absence of overlying cartilage. Remodelling of subchondral bone in osteoarthritis, at least in the short term, is fairly constant and is not related to weight bearing.


Chronic transmural bronchiolitis: a non-specific lesion of small airways.

To investigate nine patients with histological changes at open lung biopsy compatible with so-called "small airways disease"; to define these changes and distinguish them from other types of bronchiolitis; and to correlate them with clinical features, respiratory physiology, and other laboratory investigations. The open biopsy sections and the clinical records were reviewed. There was chronic inflammation of the walls of centri-acinar respiratory bronchioles and peribronchiolar alveoli. Peripheral alveoli of affected acini were spared. Although lumens were narrowed and distorted, obstruction by granulation tissue plugs was not a feature. Clinical backgrounds included Hodgkin's disease, yellow nail syndrome, sicca syndrome, asthma and psoriasis. The main presenting symptoms were cough, dyspnoea and wheeze, often associated with basal crackles and basal shadowing. There was no consistent immunological or haematological abnormality. Sputum culture was negative in six patients, and a variety of organisms were cultured from three others. In most cases respiratory function tests revealed an irreversible obstructive defect (combined in some cases with a restrictive defect), gas trapping, and well preserved gas transfer. Lung volumes were normal. Bronchodilators, with steroids and azathioprine in more seriously affected patients, stabilised the disease process. The histological changes may be distinguished from bronchiolitis obliterans and bronchiolitis obliterans organising pneumonia by the absence of intraluminal granulation tissue plugs, and from the obliterative bronchiolitis of rheumatoid disease and diffuse peribronchiolitis on clinical grounds. Although often striking, this lesion does not represent a clinico-pathological entity, and may occur in the distal lung in association with a number of different diseases. "Small airways disease" is often used by clinicians in a functional context, and may lead to confusion. It is suggested that "chronic transmural bronchiolitis" is a more appropriate term.


The effect of strontium chloride hexahydrate dentifrices on plaque accumulation and gingival inflammation.

2 strontium chloride hexahydrate-containing dentifrices (SCH), similar except for their respective abrasive systems, diatomaceous earth or silica-based, were compared for their effects on plaque accumulation and gingival inflammation as part of a 2-month randomised double-blind parallel clinical study. No attempt was made to change the patients' oral hygiene prior to participation in the study. Plaque was assessed using the Silness & Löe index and the gingival condition by the Löe & Silness index GI. There was a slight and non-significant increase in plaque accumulation at 2 weeks from baseline, but relatively negligible change thereafter, the effect being identical in both groups. Similarly, the gingival condition showed a slight index change from baseline, although it tended to be slightly higher in the diatomaceous earth group. The results do not support the conclusions of previous studies which indicated that SCH dentifrices increased plaque accumulation. Neither plaque accumulation nor gingival condition significantly changed from baseline levels during the course of the study.


Mineralized tissue-formation in periodontal wound healing.

The purpose of the present study was to examine and compare the different mineralized tissues that are found on and around the dental root following treatment of different periodontal pathosis. The material has been compiled from previously published experimental studies on periodontal therapies and trauma treatments. 4 distinctly different appearances of the mineralized tissue layers on the marginal dentin surfaces were described; new cementum, non-attached bone-like tissue, partly attached bone-like tissue and ankylosis preceded by root resorption. It was concluded that, healing in the periodontal/root interface following periodontal therapy may yield different mineralized tissues, depending on a number of host-specific and external factors. The temporal pattern of such healing processes is schematically represented.


A comparison of delmopinol and chlorhexidine on plaque regrowth over a 4-day period and salivary bacterial counts.

Delmopinol has been considered as a potential agent for the chemical control of plaque. The aims of these studies were to measure the effects of a 0.2% delmopinol hydrochloride mouthrinse on (1) plaque reformation and (2) salivary bacterial counts. Comparisons were made with a 0.2% chlorhexidine rinse and a placebo rinse. A group of 12 male volunteers took part in the plaque study which was of a double blind, randomised, 3 cell, cross-over design. From a zero plaque baseline subjects rinsed, 2x a day, under supervision, for 1 min with 10-ml volumes of the allocated rinse. After 4 days, during which no other form of oral hygiene was performed, plaque was scored by area and index. Plaque results were significantly lower with chlorhexidine and delmopinol compared with control, and with chlorhexidine compared to delmopinol. Side-effects with delmopinol were transient tingling and numbness of the tongue in some subjects. A 2nd group of 12 male volunteers received single, 1-min rinses of the 3 formulations. Salivary bacterial counts were determined immediately before and up to 420 min after rinsing. Compared to the control rinse, chlorhexidine significantly reduced bacterial counts of 420 min. Delmopinol produced a small reduction in bacterial counts which was only significantly different from control at one time point. Delmopinol deserves further evaluation as a chemical plaque inhibitor, particularly when used as an adjunct to normal toothcleaning.


Probing pocket depth at mobile/nonmobile teeth.

The aim of the present investigation was to study the influence of an increased tooth mobility on the resistance offered by the periodontal tissues to probing. 6 beagle dogs were used. At the start of the experiment, the animals had clean teeth and normal gingival and periodontal conditions. In each dog, a device was installed in the lower left jaw quadrant to expose the third premolar (P3) to jiggling forces which would enhance the mobility of this "test" tooth. The contralateral tooth served as the non-jiggled control. During the 3 months of experimentation, the teeth of the dogs were cleaned on a regular basis. Clinical examinations including tooth mobility measurements were performed on days 0 and 90. After the examination on Day 90, a probe was inserted in the buccal "pocket" of the mesial root of 3P and P3. The probe was retained with composite. Biopsies including the test or control tooth with adjacent buccal periodontal tissues were harvested, fixed and decalcified. Each biopsy was divided in one mesial and one distal portion (root). The distal portion was embedded in Epon, sectioned and stained in PAS and toluidine blue, while the mesial portion, following probe removal was embedded in paraffin, sectioned and stained in hematoxylin-eosin. The sections were exposed to histometric and morphometric measurements. The findings demonstrated that tissue alterations which occur at mobile teeth may reduce the resistance offered by the periodontal tissues to clinical probing. Such alterations include (i) reduced height of the alveolar bone, (ii) reduced amount of collagen, and increased vascularity in the enlarged supracrestal connective tissue.


The effect of supragingival plaque control on the composition of the subgingival flora in periodontal pockets.

The effect of mechanical supragingival plaque control on the composition of the subgingival microflora in untreated 4-6 mm deep periodontal pockets was investigated. 13 subjects with chronic periodontitis were recruited for the study. Periodontally-diseased sites were subjected to professional plaque control 3 x weekly for a period of 3 weeks. Contralateral sites received no prophylaxis and served as controls. No instructions in oral hygiene procedures were given to the patients who maintained their habitual oral hygiene regime during the observation period. Clinical examination and darkfield microscopic analysis of bacterial samples were performed every week. The PlI scores for the experimental sites were reduced markedly, while those for the control sites remained stable throughout the observation period. No changes in the other clinical parameters were detected during the study. The composition of the subgingival microflora at the control sites did not change during the experimental period. In contrast, at the test sites, the proportion of spirochetes+motile rods decreased continuously. This decrease reached statistical significance at the end of the experiment. The results indicate that at periodontally diseased sites with an established subgingival ecosystem, supragingival plaque removal may influence the composition of the subgingival microflora.


Guided tissue regeneration in the treatment of infrabony defects on maxillary premolars. A pilot study.

The present study evaluated clinically and radiographically the short-term results of the healing of infrabony defects at maxillary premolars treated according to guided tissue regeneration (GTR). 9 patients with bilateral presence of infrabony defects with or without furcation involvements at maxillary premolars were selected. At baseline assessments of plaque and gingival indices, bleeding, probing pocket depth and attachment level, and furcation measurements were recorded. Conventional radiographs were obtained in a way that assured a reproducible projection geometry. One premolar was randomly treated with GTR and the contralateral with open debridement. Clinical and radiographic examinations were performed again 6 months postoperatively. The bone tissue changes were assessed by means of conventional radiographs and subtraction images. Sites treated by both procedures demonstrated an improvement of gingival conditions and a reduction of pocket depths. A statistically significant attachment gain was obtained for the test (mean 1.2 mm), but not for the control sites (mean 0.6 mm). The differences, though, were not significant between the test and control sites. Limited improvement in furcation closure was recorded. The radiographic examination demonstrated loss of bone tissue in four sites treated with GTR. The findings suggest that the regeneration of the periodontal soft and bone tissues was not significantly enhanced with the GTR therapy.


Intrafamily influences on health behavior. A study of interdental cleaning behavior.

The purpose of this study was to assess quantified measures of intrafamily patterns of influence on interdental cleaning behavior based on a conceptual model of family influences on health behavior. Data stemmed from the Norwegian National Health Survey 1985, comprising 295 two-parent families with 2 children above 6 years of age. Analyses were performed with the family as the sampling unit. Logistic regression analyses were applied. The results showed that there were statistically significant associations of interdental cleaning behavior among all pairs of family members, the strongest association being between sibling (OR = 36.6). The multivariate analyses of interdental cleaning behavior of the children showed that the strongest explanatory factor was the interdental cleaning behavior of the mother (OR = 2.4). Thus, the mother seems to play an important rôle in the formation and maintenance of the elder child's interdental cleaning behavior. The highly correlated interdental cleaning behavior of the 2 siblings could be explained by correlated measurement errors as well as equity in rules and parental control and reinforcement of the behavior, in addition to substantive influential effect of the elder sibling's interdental cleaning behavior on that of the younger sibling.


The power of tests to detect differences between periodontal treatments in published studies.

10 studies comparing periodontal treatment modalities were re-examined to see if they had adequate power to detect true differences. Attachment level (AL) and pocket depth (PD) were the 2 variables assessed. A statistical test's power refers to its probability of detecting a significant sample difference in treatment means, given a predetermined value for alpha (level of significance), delta (a clinically meaningful underlying difference), and the sample size. Studies were included that stratified their data by initial pocket depths, reported sample size, and lasted at least 6 months. Power calculations were done for 173 treatment comparisons, using delta = 0.5 mm and alpha = 0.05. For shallow pockets (1-3 mm), most studies had a strong chance of detecting true differences (median power = 83%). For moderate pockets (4-6 mm), median power dropped to 38%. However, median power dropped to 14% for deep pockets (> 6 mm), with 75% of the tests having less than a 20% chance of detecting a 0.5 mm difference. Many of the modalities reported as "not significantly different" from each other have not had a fair trial, especially for deep pockets. In order to improve a study's power, 4 factors are discussed: the number of compared treatments, the expected noise or random error, the patient sample size, and the average number of sites per patient for each pocket depth category.


Crossover trials comparing several treatments.

Designs exist for crossover studies in which the possibility of distortion by carryover effects is minimised. A novel design including 5 treatments and 15 subjects with this property is presented, along with existing designs. These designs incorporating balance for carryover effects should be used in preference to cyclical permutation designs. Statistical analysis of the resulting data is readily performed.


Patient preference regarding 4 types of periodontal therapy following 3 years of maintenance follow-up.

It has been shown that certain types of periodontal therapy result in greater post-therapy gingival recession. It has been suggested that this recession may lead to maintenance complications for patients. This study evaluated patient perceptions 3 years following the completion of 4 types of periodontal therapy (coronal scaling (CS), root planing (RP), modified Widman surgery (MW), and flap with osseous resectional surgery (FO)). 75 individuals completed split-mouth therapy and 3 years of maintenance follow-up. An interview survey of all patients categorized their perception for each treatment of their mouth concerning difficulty in cleaning, sensitivity to temperature, general "feeling" of the region, prevalence of localized symptoms, food retention, comfort of oral examination, and attitude toward repeating therapy. Responses to questions showed no statistically significant differences between treatment regions. Patterns demonstrated that FO-treated regions were perceived to have less food retention, but were more difficult to clean. It was generally found that at the end of 3 years of maintenance, patients felt their mouths were "normal", they experienced few localized symptoms, and were very willing to repeat any of the treatment regimens if necessary.


Periodontal changes by HIV serostatus in a cohort of homosexual and bisexual men.

These data represent 20 months of follow-up on 114 homo/bisexual men. Periodontal changes were analyzed in relation to HIV-1 serostatus, immune status, age and plaque. Gingival index (GI), plaque index (PI), and relative attachment levels recorded by the computerized Florida disk probe were performed every 4 months. A threshold of > or = 3.0 mm of relative attachment loss (RAL) was selected as a significant longitudinal change. RAL > or = 3 mm occurred 6.16 times (95% CI = 1.95, 19.40) more frequently among subjects with T4 counts < 200 compared to subjects with counts of 200 or more. Among older subjects (age > or = 35 years), the incidence (33%) of RAL > or = 3 mm was significantly higher (p = 0.004) in more immunosuppressed subjects (T4 < 200) compared to the incidence (5%) in less immunosuppressed subjects (T4 > or = 200); this association was not significant in younger subjects less than 35 years old (p = 0.55). In 78 subjects present at all follow-up visits, averaged GI increased and were significantly higher in the seropositive subjects compared to seronegative subjects, but, GI was not related to T4 cell counts within the seropositive group. Separate linear regression of GI by PI by HIV serostatus revealed a significantly higher slope in the seropositive group compared to the seronegative group (p = 0.04), suggesting greater sensitivity to plaque in the seropositive group. immunosuppression, especially in combination with older age, may be a risk factor for attachment loss, and HIV seropositivity, independent of T4 cell counts, may be a risk factor for gingival inflammation.


The effect of supragingival plaque control on the subgingival microbiota in subjects with periodontal disease.

The present investigation was performed to study the effect on the subgingival microbiota, of a plaque control program which included meticulous oral hygiene instruction, supragingival scaling and professional monitoring during a 2 year period. 300 subjects were examined for periodontal disease and monitored for 2 years without treatment. After the 2 year examination, 80 subjects were invited to participate in a treatment program intended to improve the standard of their self-performed plaque control. 40 of the invitees had a gingivitis and only minor attachment loss, while 40 subjects had moderate signs of periodontitis. 62 subjects volunteered for this treatment. 23 of the volunteers (Group AB) had several sites with deep pockets (> 4 mm). 39 of the volunteers had gingivitis but shallow pockets only (Group C). Group AB contributed 31 shallow pocket sites (A-sites) and 40 deep pocket sites (B-sites), while Group C contributed 63 shallow sites (C-sites). After the clinical examination, samples of the subgingival microbiota were harvested from the 134 A, B and C sites. The 62 subjects were enrolled in a supervised oral hygiene program. Supragingival scaling was carried out. Oral hygiene instruction was provided and repeated on an individual need basis so that all subjects reached and maintained a supragingival plaque score which was < 20%. 24 months after the year 2 examination, the 62 subjects were examined again using both clinical and microbiological examination procedures. The findings demonstrated that carefully performed supragingival plaque control changed the quantity and the composition of the supragingival microbiota.(ABSTRACT TRUNCATED AT 250 WORDS)


A survey and review of hepatobiliary lesions in Australian macropods.

This report presents information on the range of diseases and lesions that occurred in sections of livers of macropods held in the Non-Domestic Animal Registry at Taronga Zoo. Of 142 affected livers, 52 were due to parasites, 24 to bacteria, nine to Macropod Herpesvirus, four to fungal agents and ten to tumours. In addition, 17 livers had acute degenerative or necrotic lesions, 22 were affected by fibrosis or other chronic lesions and four had miscellaneous degenerative lesions. Common parasitic diseases included toxoplasmosis, coccidial cholangitis, cestode cholangitis (Progamotaenia sp.), fascioliasis and capillarial hepatitis. Bacterial diseases were varied but lesions due to anaerobic bacteria or Mycobacteria spp. were most common. Many of the acute degenerative lesions were associated with cardio-respiratory disease. Chronic lesions were often of unknown origin, although it was speculated that parasitic and bacterial organisms contributed to the aetiology. There were four primary and six metastatic tumours.


Peripheral neuropathy in German shepherd dogs.

Three aged (10-year-old) German Shepherd Dog litter mates, separately reared, were affected with familial and adult onset peripheral neuropathy. They developed clinical signs, unsteady gait of their hind legs with progressive muscular weakness at almost the same time. The main lesions were systemic neurogenic muscular atrophy, segmental demyelination and Wallerian degeneration of the peripheral nerve fibres. Histochemically, collateral ramification and multiple terminal arborization were observed in terminal axons of motor neurones in the muscles. These changes were attributed to a dying-back process.


Immunofluorescent antibody response to lactic dehydrogenase virus in different strains of mice.

The development of antibody against lactic dehydrogenase virus in five strains of mice (NZB x NZWF1, BALB/c, C.B-17, ICR and C.B-17 scid or SCID mice) was examined by indirect immunofluorescence (IIF) of infected liver sections. IIF antibody appeared 1 to 3 weeks and rose progressively 2 to 4 weeks after infection in four strains of mice (NZB x NZWF1, BALB/c, C.B-17 and ICR mice). SCID mice did not develop antibody. These results suggest that IIF may be applicable for detecting LDV infection in many other ordinary strains of mice.


Histochemistry of glandular metaplasia at the trigone of the urinary bladder in cows.

The epithelium at the trigone of the urinary bladder showed intestinal metaplasia of a colonic type in three Holstein-Friesian cows affected with chronic polypoid cystitis. Except for Ricinus communis (RCA-I), almost all goblet cells in the whole crypt were positive to periodic acid-Schiff (PAS), alcian blue (AB) pH 2.5, AB pH 1.0, periodate borohydride-potassium hydroxide-PAS (PB-KOH-PAS), Ulex europaeus (UEA-I), Triticum vulgare (WGA) and Arachis hypogaea (PNA) after neuraminidase digestion. This result indicated that most goblet cells contained acidic and neutral glycoconjugates as O-acetylated sialomucin, L-fucose, N-acetyl-glucosamine, neuraminic acid residues and sialic acid-galactose dimers and were devoid of beta-D-galactose. The goblet cells at the surface in the upper half of the crypt contained both sulpho- and sialo-mucins with N-acetyl-galactosamine residues by AB (pH 2.5)-PAS, high iron diamine (HID)-AB (pH 2.5), Dolichos biflorus (DBA) and Glycine maximus (SBA) reactions. On the other hand, the lower goblet cells were found to contain predominantly sulphated mucins with D-mannose and D-glucose residues by AB-PAS, HID-AB and Concanavalia ensiformis (Con A) reactivities. This suggested that mucin secreted from these cells was similar to that secreted from the goblet cells of the large intestine in cattle.


A pathological study of bovine alimentary mycosis.

A 10-year study showed that 45 of 692 cattle aged > 6 months had systemic mycosis and, of these, 38 had alimentary mycosis. The percentages of these 38 cattle with lesions in various sites were: rumen (73.7), omasum (71.1), abomasum (34.2), reticulum (21.1), intestine (15.8), omasoabomasal orifice (7.9) and tongue (2.6). Infections in both the forestomachs and abomasum occurred in 31.6 per cent; mucormycosis was found in 94.7 per cent and aspergillosis in 31.6 per cent; 26.3 per cent (10 cattle) had complicated infections with both Mucorales and Aspergillus and eight of these animals had mixed lesions of both mucormycosis and aspergillosis. Macroscopically, focal haemorrhagic necrosis was seen in all 38 cattle. Histologically, thrombosis, coagulative necrosis and hyphae typical of the order Mucorales or of Aspergillus spp. were found. Many of the cattle were also affected by ruminal acidosis-inducing factors (ruminal atony 81.6 per cent, mastitis 63.2 per cent, "downer cow syndrome" 57.9 per cent and parturition 50.0 per cent), which may have predisposed to alimentary mycosis.


An epidemic of toxoplasmosis in a captive colony of squirrel monkeys (Saimiri sciureus).

An epidemic of acute, disseminated toxoplasmosis caused 30 per cent mortality and an apparent 100 per cent morbidity in a captive colony of squirrel monkeys (Saimiri sciureus). The source of the infection could not be elucidated. Although most deaths were due to pulmonary oedema, one monkey probably died of heart and liver failure. These findings support the view that New World monkeys are unusually sensitive to Toxoplasma gondii infection. The similarity of the disease in these monkeys with that in immunocompromised human beings is an observation worthy of further investigation.


Immunopathology in Aujeszky's disease virus-infected pigs exposed to fluctuating temperatures.

Pigs exposed to fluctuating temperatures (high, 30 +/- 2 degrees C; low, 4 +/- 1 degrees C) were intranasally inoculated with Aujeszky's disease virus (ADV). ADV-infected pigs, exposed to the fluctuating temperatures, showed severe clinical signs and ADV in the nasal secretions persisted longer than in the ADV-infected control pigs kept at the normal temperature (20 +/- 2 degrees C). High concentrations of ADV were isolated from nasal secretions on the 1st day after inoculation of the virus. Pathologically, all ADV-infected pigs had non-suppurative encephalitis and trigeminal ganglionitis. The lesions were more widely distributed in pigs exposed to fluctuating temperatures than in infected control pigs. Two infected pigs given the stress had severe malacic foci in the frontal lobe and four of them had prominent interstitial pneumonia. In the pigs exposed to fluctuating temperatures, a significant number of immunoglobulin-containing cells, especially IgM-containing cells, did not respond to ADV infection. A significant (P < 0.01) difference in the number of IgG- and IgM-containing cells was observed between the ADV-infected pigs exposed to the fluctuating temperature and ADV-infected control pigs, respectively. These results demonstrated that the stress of fluctuating temperatures enhanced the susceptibility to ADV infection.


Neosporosis in the aborted fetus and newborn calf.

Protozoal encephalitic lesions were found in four aborted fetuses and one dead newborn calf. The organism was identified as Neospora caninum by immunoperoxidase. The brain lesions were of two forms. One was observed in three fetuses of 5 months gestation and was characterized by multifocal necrosis. The other was found in a 7-month fetus and in a newborn calf, and showed severe infiltration with macrophages and plasma cells containing IgG. This association, between the age of fetus and inflammation, may reflect development of the immune system in bovine fetuses.


Isolation of Brucella melitensis from aborting ruminants in Jordan.

Thirty-four isolates (16.5 per cent) of Brucella melitensis were cultured from 206 samples from aborted, still-born or weak full-term animals and vaginal swabs from aborted animals. Twenty-six of 31 isolates from sheep were B. melitensis biovar 3. Two isolates were biovar 1 and one of these was the vaccine strain Rev 1. The three remaining isolates were from vaginal swabs and were not biotyped since B. melitensis biovar 3 had been isolated from the aborted fetuses. One of two isolates from cattle and one isolate from a goat were biovar 1. The remaining cattle isolate was biovar 3.


Managing change: strategies for continuing education.

Nurses who provide continuing education have a role, primarily through staff education, in helping to bring about change within their institutions. To fulfill this role requires that nurse educators understand the change process and anticipate the range of human responses to it. This article presents an overview of two change theories that incorporate strategies for CE offerings that facilitate the implementation of change.


Nursing internships: taking a second look.

Nursing internships are associated with recruitment and retention efforts of hospitals to gain new nursing employees. They are recognized as a benefit to new nursing staff and the hospital as well. Reported to bridge the gap and ease the transition to registered nurse, internships have been reported in the literature for over 30 years. But how effective are they? This article reviews the recent literature for evidence that internship programs improve recruitment and retention, have a positive cost benefit ratio, and ease the role transition of newly employed nurses.


Enjoyable learning experiences--an aid to retention?

Stress is related to job dissatisfaction and is a significant factor in high turnover rates for nursing staff. In the current labor market, all possible aids to retention need to be considered and innovative approaches need to be tried. Perhaps one of the most powerful retention tools, laughter, is being overlooked. Research indicates that laughter and humor have positive effects by reducing stress and enhancing the immune system. Stress within the hospital environment contributes to burnout. Burnout results in absenteeism, decreased productivity, and turnover. Incorporating laughter and humor into educational programs is one strategy to reduce stress and may be an antidote for burnout. A game called "Not So Trivial ... Protective Pursuit" was used with 150 staff on the evening and night shift. The observed effects were very positive. The implications are that nurse educators can make a significant contribution to preventing hospital burnout by making learning experiences enjoyable.


Preceptors: a comparison of their perceived needs before and after the preceptor experience.

This study supports the need to establish selection criteria that emphasize an individual's clinical experiences as part of the preceptor application process. This study further supports the need to provide a comprehensive workshop to prepare participants for the preceptor role.


An orientation program for new graduate nurses: the basis of staff development and retention.

The nursing shortage and an increased demand for obstetric nurses led a Central Texas hospital to hire new graduates for the Level Three obstetric unit. This change in hiring policy necessitated a reevaluation of the orientation program resulting in a new approach in staff development. A three-phase program was developed beginning with orientation and socialization of the new staff member, continuing with the development of advanced skills, and leading to assignments of complex cases after completing appropriate educational programs. The program has fostered autonomy in the experienced staff nurse and increased job satisfaction as measured by advancement in the career ladder and retention rate. The program is regularly monitored by chart and peer review audits, as well as by the orientees' six-week and six-month evaluations.


Characterization and kinetics of gastric emptying of peptides derived from milk proteins in the preruminant calf.

The gastric emptying kinetics of peptides derived from milk protein were studied in vivo in preruminant calves by collecting and characterizing the whole effluent leaving the stomach for 12 h after ingestion of crude skim milk. Peptides were isolated by reversed-phase HPLC and identified. Particular attention was paid to biologically active peptides and to peptides that could be precursors of biologically active sequences. A gastrin inhibitor, the caseinomacropeptide, was emptied from the stomach only during the first 0.5 h of digestion and rapidly hydrolysed. Precursors of immunostimulatory peptides from alpha s1- and beta-caseins were emptied throughout digestion in the gastric effluent. A precursor of beta-casomorphins (peptide 58-93 of beta-casein) was emptied from the stomach 3.5 h after the meal when it was taken on an empty stomach. From this precursor, peptides that may be resistant to hydrolysis by intestinal peptidase were obtained after in vitro hydrolysis by pancreatic enzymes. A phosphopeptide (fragment 110-142 of alpha s1-casein) was also found in digesta after a few hours of digestion. When the meal was not taken on an empty stomach, these peptides were emptied in the first digesta at a low concentration. The potential activity of these peptides is discussed. The results support the hypothesis that active sequences could still be present in the gut after the action of pancreatic enzymes.


Using a game format to improve compliance with required review of hospital standards and policies.

Maintaining quality patient care requires frequent review of hospital standards and policies. This repetition, however, proves to be boring and not much fun, resulting in poor staff participation. The anticipation of a visit from the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) provided the impetus for individual nursing units to develop a means of addressing this problem. Utilizing shared governance concepts, staff developed a game format to stimulate interest. This not only made learning and reviewing fun, but also empowered the staff to become accountable for the quality of their work. This article describes the development of the game format, its implementation, and evaluation of its effectiveness.


Cost benefit analysis of bovine mastitis in the UK.

Bovine mastitis reduces the yield and quality of milk and increases the rate of culling and veterinary costs. This reduces the profitability of farm milk production but the calculation of the extent of this economic loss is complex because of the many factors involved and deficiencies in the evidence on the relationship between the disease and various production factors. This paper examines the available evidence for the UK and provides a consistent analytical framework within which the benefits arising from reduced mastitis in dairy herds constrained by quota can be considered. It is estimated that since 1970 the farms that have followed the recommended control procedures have reduced the average annual number of cases of clinical mastitis from 135 to 40 cases/100 cows each year, while the quarters remaining uninfected for a whole year has increased from 65 to 80% of the total quarters. The costs of the main control procedures (e.g. 8.60 pounds/cow for dry-cow therapy and teat dipping or spraying) are broadly covered by the reduction in clinical mastitis, leaving the benefits of reduced subclinical infection (e.g. 3810 pounds for a 100 cow herd unconstrained by quota and achieving the average reduction in infection) as a substantial bonus. The imposition of quotas reduces the financial benefit of mastitis control but it still remains a worthwhile investment. The results of this analysis can be used to suggest maximum costs of additional new control measures produced by research. It also indicates that there is considerable value in production research which gives more precise knowledge of production systems, thus allowing producers to respond optimally to quota cuts.


Efficacy of a substance abuse primary prevention skills conference for nurses.

A conference on substance abuse prevention skills was presented by the New York State Nurses Association (NYSNA) to provide nurses with skills to help patients in various practice settings. Information covered assessment, intervention, and tools for interviewing and identifying resources. A six-month follow-up evaluation showed that the majority of the participants incorporated the skills in their nursing practice primarily in interviewing and use of assessment questions. Directions for future conferences were identified.


A 10-year follow-up study: nurse refresher program.

A university-based school of nursing has provided a refresher course for inactive nurses since 1980. In 1985, the nursing shortage and declining enrollments in generic nursing schools emphasized the need to return inactive nurses to work. This article describes the 10-year follow-up evaluation of the course with attention to the long-term effectiveness in returning inactive registered nurses to the work force. This study also describes the employment profile of course graduates and the continuing education acquired by respondents since completing the course. Of the 71 respondents, 91% successfully reentered the work force and remained employed in nursing. Nearly half of these individuals were employed in acute care settings. Further, the employment profile of the working graduates showed that 74% had obtained an initial nursing position and remained in it until the time of the follow-up evaluation. Implications of the study and changes planned for the course are also described.


RN students' satisfaction with clinical teaching in a distance education program.

This study examined student satisfaction with clinical teaching and student-perceived difficulties in three introductory nursing courses offered by distance education. The sample consisted of 41 registered nurse respondents enrolled in a baccalaureate nursing program. Quantitative and qualitative data were collected by mailed questionnaire. The results indicate that the degree of satisfaction with the clinical teacher role was high and that unfamiliarity with the clinical settings and roles were perceived as difficulties. As well, the qualitative data suggest that RN learners need gradual exposure to self-directed learning to acquire these skills.


Effect of mastitis on plasminogen activator activity of milk somatic cells.

This study was conducted to examine the effects of mastitis and stage of lactation on plasminogen activator (PA) activity in milk somatic cells. An assay system, which measures the plasmin-mediated hydrolysis of the chromogenic substrate D-valyl-leucyl-lysine p-nitroanilide, was used to assess PA activity present within milk somatic cells. Milk cell associated PA activity was increased (P < 0.05) by 50% in the presence of fibrin fragments. This suggests that milk somatic cells contain tissue PA which, unlike urokinase PA, is preferentially activated in the presence of fibrin fragments. An increase of the milk somatic cell count from < 5 x 10(4) to > 10(6) cells/ml resulted in an 8-fold increase in PA activity per cell. Elevated levels of PA activity were associated with milk somatic cells isolated from mastitic quarters obtained from cows in early (< 4 months in lactation) or late lactation (> 8 months in lactation). We conclude that PA activity is increased during severe mastitic inflammation. Although the physiological function of this enzyme is as yet unclear, we propose that it may be involved in the conversion of plasminogen to plasmin, contributing to the higher levels of plasmin occurring in milk isolated from mastitic quarters.


Transepithelial potential difference in the goat mammary gland and its change during hand milking, and administration of oxytocin and catecholamines.

The reaction of secretory epithelium and myoepithelial cells in the alveoli to hand milking and i.v. injection of oxytocin and catecholamines was studied in lactating goats. The reaction of secretory cells was assessed by changes in the transepithelial (blood-milk) potential difference (PD), and the contractile reaction of myoepithelial cells by the growth of intramammary pressure (IP). The initial value of PD was 24.6 +/- 0.6 mV, that of IP 3.32 +/- 0.08 kPa (24.9 +/- 0.6 mmHg). Milking and oxytocin administration caused a rise in PD and an increase in IP. After noradrenaline and adrenaline injections two-phase PD changes and a short-term rise in IP were recorded. Isoproterenol, a beta-agonist, caused a rise in PD but did not affect IP. Phenylephrine, an alpha-agonist, caused two-phase and one-phase changes in PD. Simultaneously, a rise in IP was recorded. The results show that the reaction of the mammary gland to the substances administered is complex. Myoepithelial and secretory cells respond differently to short-term rises in the level of mediators and hormones in the blood.


Aetiology of disturbed milk ejection in parturient primiparous cows.

Milk flow in nine primiparous cows with disturbed milk ejection (D) and in six corresponding control animals (C) with normal milk removal was recorded during machine milking and blood samples were taken before and during milking to determine plasma oxytocin, vasopressin, prolactin, cortisol, oestradiol-17 beta, luteinizing hormone, progesterone and beta-endorphin concentrations. Manual teat stimulation before milking lasted for 1 min. After milk flow had stopped, air was blown into the vagina for 2 min. When milk flow had stopped again, 1 i.u. oxytocin and finally 10 i.u. oxytocin were injected to remove residual milk. During and after teat stimulation, oxytocin remained basal in D, but increased in C, whereas prolactin increased in both groups. While 94% of total milk was obtained in C during this period, only 9% could be removed from D, indicating lack of alveolar milk ejection. During vaginal stimulation, oxytocin increased transiently in D and more than by teat stimulation in C. This allowed the removal of 75% of milk in D, whereas almost no more milk was available in C. After oxytocin injections, 3 and 16% of residual milk were obtained in C and D respectively. Basal oestradiol-17 beta concentration was higher in D than in C (11.6 and 2.0 ng/l respectively), whereas beta-endorphin level was lower (24.1 and 86.6 micrograms/l respectively). Basal concentration of luteinizing hormone and progesterone, and concentration of cortisol and vasopressin before and during milking were comparable in C and D. We conclude that in cows with disturbed milk ejection afferent nervous pathways to the hypothalamus were intact, because prolactin was released by teat stimulation. However, oxytocin was only released by vaginal stimulation, i.e. milk ejection was centrally inhibited during teat stimulation.


Effect of methionyl bovine somatotropin in a prolonged-release vehicle on milk production, hormone profiles and health in dairy cows.

Milk production of dairy cows in 14 herds was increased by 3.8-32.1% by the administration of recombinant methionyl bovine somatotropin (bST) in a sustained-release vehicle at 14 d intervals at 40-94 d post partum. A greater response in multiparous than in primiparous cows was found in cows turned out to graze spring pasture. Administration of recombinant bST resulted in elevated plasma bST during the first 9 d after injection. Clinical characteristics such as respiration, heart rate and body temperature were unaffected by bST treatment, as were blood erythrocyte and leucocyte counts, haemoglobin concentrations and haematocrit values. Plasma levels of glucose, free fatty acids, urea and P, and serum alanine aminotransferase and aspartate aminotransferase were not affected by bST treatment, and acetone was not detected. No adverse effects of bST on general health, infection status of mammary glands, mastitis incidence and reproduction were found.


Heat-related changes to the hydrophobicity of cheese whey correlate with levels of native beta-lactoglobulin and alpha-lactalbumin.

Correlations were identified between levels of the native whey proteins, beta-lactoglobulin and alpha-lactalbumin and the surface and total hydrophobicities of cheese whey in response to different heat treatments. Heat-induced changes in the native beta-lactoglobulin content and surface hydrophobicity of whey exhibited the most significant linear relationship while correlations between total hydrophobicity and the native proteins were less significant because of an atypical rise in the n-heptane-binding capacity of whey after high-temperature treatment. The content of native beta-lactoglobulin in whey was more sensitive to heating than the content of native alpha-lactalbumin, while heat-related changes in the total hydrophobicity of whey were generally greater than similar changes in surface hydrophobicity.


Studies on antimutagenic effect of milk cultured with lactic acid bacteria on the Trp-P2-induced mutagenicity to TA98 strain of Salmonella typhimurium.

The inhibitory effects of cultured milk using 76 strains of lactic acid bacteria isolated from milk products were investigated on the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P2), a tryptophan pyrolysate for Salmonella typhimurium TA98. Each cultured milk sample displayed its characteristic antimutagenic effect against the mutagenicity of Trp-P2. The milk cultured with Lactobacillus acidophilus LA106 (LA2) showed the highest inhibition of 82.1% among the strains used. Milk samples cultured with Lactococcus lactis subsp. lactis, Lll103 (10-3) and Lll102 (KM) also exhibited higher inhibition percentages.


Salmonellae, salmonellosis, and dairy foods: a review.

Salmonellae continue to be a major concern for the dairy industry because these bacteria have caused recent outbreaks of illness and have been isolated from various dairy products in the market place. Salmonellae are generally not heat resistant and normally grow at 35 to 37 degrees C, but they can grow at much lower temperatures, provided that the incubation time is suitably extended. To minimize problems, foods should be held at or below 2 to 5 degrees C at all times. Both conventional and rapid methods are available to isolate salmonellae from dairy foods and to identify the bacteria. Salmonellae behave differently in different kinds of cheese: they survived in ripening Cheddar cheese for up to 7 mo at 13 degrees C and for 10 mo at 7 degrees C; in coldpack cheese food for several weeks, depending on the pH and preservative used; and in Domiati cheese 13 to 36 d, depending on the manufacturing process used. When Mozzarella cheese was made, temperatures of stretching and molding (60 degrees C) killed all salmonellae present, but, in cottage cheese, survival of the pathogen depended on the cooking temperature of curd. Spray drying of skim milk killed substantial numbers of salmonellae, but some survivors remained. Butter readily supported growth of salmonellae at room temperature, and neither freezing nor refrigeration for brief periods eliminated salmonellae from butter. Use of appropriate hygienic procedures, e.g., Hazard Analysis Critical Control Point system, during processing should reduce the likelihood of salmonellosis outbreaks associated with dairy foods.


Growth and activities of Lactococcus lactis in milk enriched with low mineral retentate powders.

The growth and activities of three strains of Lactococcus lactis ssp. cremoris (Wg2, E8, and HP) and their proteinase-negative variants were studied in skim milk enriched with three types of retentate powder. The performance of these strains in enriched milks was compared with that determined in reconstituted skim milk. Proteinase-positive strains of L. lactis ssp. cremoris exhibited higher maximum specific growth rates than protease-negative variants. Moreover, maximum specific growth rates of lactococci were lower in skim milk than in enriched milk with a high buffering capacity. The performance of proteinase-positive strains was better than that of proteinase-negative variants. Growth of proteinase-positive lactococci in milk media increased alpha-amino groups as determined by the increase of equivalent glutamic acid concentration. Available alpha-amino groups decreased with proteinase-negative variants. Proteinase-positive strain Wg2 exhibited the most proteolytic activity but showed the least specific overall productivity of lactic acid despite high biomass concentration in milk. Among proteinase-positive lactococci, strain E8 produced more lactic acid than other strains, and, among proteinase-negative variants, strain HP had the best specific overall productivity of lactic acid.


Production of an electrolyte beverage from milk permeate.

The objective of this study was to prepare shelf-stable electrolyte beverages from milk permeate. The average composition of permeate was 4.59% total solids and .40% ash. Lactose was hydrolyzed (approximately 80%) with a commercial fungal lactase enzyme. Additional sweetness was provided by sucrose. The pH was reduced to 3.5 to 3.8 by the addition of citric acid. Shelf-stable products were made using four processes: 1) UHT followed by aseptic filling, 2) heating of filled bottles to 85 degrees C for 30 min, 3) addition of .05% benzoate, and 4) nanopore filtration. The mineral composition of the finished product, expressed in parts per million, was calcium, 150; phosphorus, 157; magnesium, 43; potassium, 1166; sodium, 286; iron, 17; copper, 8; and zinc, 3.4. Listeria monocytogenes, Salmonella dublin, Salmonella typhimurium, Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae grew well when they were inoculated into unacidified, hydrolyzed permeate. None of these organisms were isolated from properly processed products. A shelf-stable electrolyte beverage high in minerals was made from whole milk permeate. This beverage could be used to replace electrolytes lost from the human body. The production of a permeate beverage would help alleviate disposal problems of permeate.


Vitamin A supplementation of Holsteins at high concentrations: progesterone and reproductive responses.

Five trials involving 168 Holstein cows and 20 heifers were conducted to determine the effect of vitamin A supplementation at high concentrations, 1 or 2 million IU, compared with 100,000 IU/d, on peripheral concentrations of progesterone and on several measures of reproductive performance. Supplemental vitamin A at high concentrations had no effect on circulating concentrations of progesterone in either cyclic or pregnant cows or on most measures of reproductive performance examined in trials. Thus, it was concluded that providing vitamin A at these high concentrations is not warranted.


Evaluation of a system for rating edema in dairy cattle.

Our objective was to evaluate a subjective edema rating system to quantitate edema severity. Edema was evaluated with 20 nulliparous Holstein heifers from 3 wk before their expected calving date until 3 wk postpartum. Severity of udder edema was evaluated independently daily by five people throughout the 68-d experiment; a 10-point rating system (0 = no edema, 10 = severe edema) was used. One of the people developing the scoring system served as the official scorer. The accuracy of the rating system, defined as the closeness of test evaluator scores to official scores, was highest for scores 2 to 8. The precision of the system, identified by the standard error of the mean, was similar for each score in the rating system. The largest disagreement between official and test evaluator scores was evident postpartum. The large number of defined points in this rating system and the similarity between official and test scores in this study indicate the usefulness of this tool to evaluate precisely the severity of edema in dairy cattle.


Influence of calcium chloride fed prepartum on severity of edema and lactational performance of dairy heifers.

Twenty Holstein heifers in a completely randomized design were used to evaluate the effects of prepartum dietary CaCl2 on the development and regression of edema and on subsequent lactational performance. Heifers were assigned to diets containing either 2.17% limestone or 1.5% CaCl2 (DM basis) at 3 wk before expected calving date. Except for the Ca sources, diets were identical. Test diets were only fed prepartum; at calving, all heifers were offered a lactation diet for 3 wk. Severity of edema was evaluated independently by five people daily throughout the experiment; a 10-point rating system was utilized to quantify the severity of edema. Calcium chloride reduced the severity of edema, although this response was most evident during the 1st wk that this salt was fed. The beneficial effects of CaCl2 on edema prepartum disappeared postpartum, when CaCl2 was removed from the diet. Indeed, edema was higher for heifers fed CaCl2 than for those fed limestone at 2 wk postpartum. Calcium chloride reduced DMI prepartum, but, following parturition, a compensatory increase in feed intake occurred. Postpartum daily DMI averaged 1.3 kg higher for heifers fed CaCl2 than for those fed the limestone diet prepartum. Milk yield and composition were somewhat lower for heifers fed CaCl2, although this response was most evident at 1 wk postpartum. Feeding CaCl2 prepartum to prevent milk fever also may reduce the severity of udder edema prepartum and increase feed intake during early lactation.


Etiology of acetonemia in Norwegian cattle. 1. Effect of ketogenic silage, season, energy level, and genetic factors.

Plasma acetoacetate concentration in the 1st mo of lactation and its relation to BW change, milk yield, DMI, and BW postpartum were studied in 361 first lactation cows during 6 yr. The cows were fed concentrate at 6 and 3 kg/d. Calvings took place from August to December. Single observations for all cows were fitted by a multitrait animal model that accounted for all genetic relationships. Heritability for acetoacetate was .11 with a genetic correlation of .87 for milk yield, -.65 for weight change, and -.13 for BW postpartum. Acetoacetate was higher at 3 kg/d of concentrate than at 6 kg/d, and calving after 3 to 4 mo of indoor feeding was related to higher acetoacetate than was calving shortly after the pasture season. Acetoacetate was related to weight loss postpartum, but at a different degree in different years. In some years, compounds of the silage caused strongly elevated plasma concentrations of acetoacetate after feeding. Experiments were performed to compare hay with silages of different qualities. Rumen concentration of different amines 3 h postfeeding was taken as an index of the amine load of the cow. The concentration of several amines in rumen fluid were high after feeding ketogenic silage.


Etiology of acetonemia in Norwegian cattle. 2. Effect of butyric acid, valeric acid, and putrescine.

A feeding experiment was performed on 16 cows in order to test the effect of naturally occurring substances in silage on forage intake, ketonemia, and milk yield. The cows were divided into a control group and three experimental groups. The cows in the three experimental groups were fed 100 g/d of putrescine, 200 g/d of valeric acid, or 200 g/d of butyric acid through a ruminal tube for 3 d. Butyric acid increased plasma acetoacetate; the effect was largest in high yielding cows. Putrescine influenced both milk yield and forage intake and may possibly be a contributory factor, alone or combined with other amines, for the development of ketonemia. Valeric acid did not influence feed intake or plasma acetoacetate concentration. A rapid method for acetoacetate analysis also is described.


Ruminal in vitro degradability of protein in alfalfa harvested as standing forage or baled hay.

Eighty-nine samples, 45 of standing forage and 44 of baled hay, were collected from alfalfa harvested at various maturities over three cuttings each during 2 yr. Alfalfa was cut and conditioned mechanically; samples of standing forage were collected by removing bunches of forage from windrows and freeze-drying them. Forage was allowed to field cure and was harvested at an average 80% DM as small rectangular bales; samples of baled hay were collected by coring bales after storing for 3 to 6 mo. Samples were analyzed for DM, ADF, total N, fractions of total N present as ADIN, N degraded at 0 h, and potentially degradable protein N. Ruminal protein degradation rates and escapes were estimated using an inhibitor in vitro system, assuming that ADIN was unavailable and that ruminal passage rate was .06/h. Standing forage contained smaller fractions of ADIN and N degraded at 0 h, contained a larger fraction of potentially degradable N, and had more rapid degradation rates and lower estimated protein escapes than baled hay. Mean degradation rates and estimated escapes were .171/h and 24% for standing forage and .075/h and 40% for baled hay. There were no differences in degradation rate or estimated escape because of harvest year, and neither was significantly related to maturity or to ADF concentration. Results indicate a significant advantage in ruminal protein escape, compared with grazed alfalfa, for alfalfa harvested and stored as hay.


In vivo degradation of protein in diets formulated for two degradabilities.

In vivo protein degradability of two basal diets and bacterial protein synthesis were determined in four lactating dairy cows equipped with ruminal and duodenal cannulas. The diets contained corn silage, high moisture corn, and either soybean meal or a 60:40 mixture of soybean meal and corn gluten meal. Diets had calculated ruminal protein degradabilities of 69.3 and 62.3%, respectively. Both diets contained approximately 14% CP and 21% ADF. Duodenal flows of total N, total protein N, microbial N, and duodenal recovery of ingested N tended to be higher for the soybean meal and corn gluten meal diet; ruminally degraded CP was significantly lower than for the soybean meal diet. Ruminal ammonia and plasma urea concentrations tended to be higher for the soybean meal diet, as were molar percentages of butyrate and valerate. Ruminal and total tract apparent digestibilities of CP and OM were not significantly different between diets. Ruminal degradation of protein in the two diets differed by the amount predicted by the NRC system for lactating cows, although absolute values were lower than most previous estimates for similar diets.


Effect of fish meal and expeller-processed soybean meal fed to dairy cows receiving bovine somatotropin (sometribove).

Forty-eight multiparous cows were blocked by calving date and milk production and assigned randomly to a TMR formulated to contain 68 or 55% of dietary CP as ruminally degradable CP. Diets contained corn silage, alfalfa haylage, and ground corn. Supplemental CP was soybean meal for the control diet or a combination of soybean meal, expeller-processed soybean meal, and fish meal for the low degradable protein diet. Two 10-wk phases began on d 31 +/- 3 (phase 1) and 110 +/- 7 postpartum [phase 2, all cows received subcutaneous implantations of pelleted (400 mg) bST (sometribove) every 14 d]. Dietary energy, CP, ruminally degradable CP, NDF, and ADF were similar between dietary treatments. Production of FCM increased in response to bST but was not affected by dietary treatment. Cows fed the expeller-processed soybean meal and fish meal TMR produced milk that contained less milk fat in phase 1 and less milk protein content in both phases. The DMI, BW, and body condition scores were not affected by diet. Hematocrit, plasma urea N, albumin, total protein, creatinine, glucose, and serum insulin were similar between dietary treatments. Replacing soybean meal with expeller processed soybean meal and fish meal did not affect ruminal degradation of protein or milk production but decreased milk fat and protein contents.


Fatty acids, calcium soaps of fatty acids, and cottonseeds fed to high yielding cows.

We examined the effects of dietary fat as cottonseed, fatty acids, or calcium soaps of fatty acids in the rations of high yielding lactating cows receiving low forage. Experiments were with isoenergetic, isonitrogenous diets containing equal amounts of forage. Inclusion of up to 510 g/d of fatty acids in the ration enhanced FCM yield. With cottonseed, increased FCM was mainly due to increased fat yield. Dietary fatty acids tended to increase milk in mid and late lactation and to decrease fat percentage. Calcium soaps of fatty acids enhanced FCM, particularly in early lactation. Feeding cottonseed and fatty acids together did not enhance yield. Effects described may be attributed in part to changes in ruminal fermentation in which cottonseed increased acetate concentrations and fatty acids decreased the ratio of acetate and butyrate to propionate and in part to enhanced efficiency of milk yield when fat was included in the ration.


Weekly balancing crude protein in diets for Holstein cows throughout lactation using one versus two grains.

Holstein cows (n = 72, 28 primiparous) were fed for ad libitum intake a forage mixture (corn and haycrop silages, 63:37 DM) and a 71:29 ratio of two grain mixtures (13.8 and 36.2% CP, DM basis) at 1 kg/2.5 kg of the previous day's milk during 1 to 28 DIM (covariate period). Thereafter, rations were balanced and adjusted for energy and CP weekly based on monthly DHI data, forage analyses, and NRC requirements. Cows were blocked by parity (1 vs. greater than 1) and assigned randomly to receive one grain (blend of 13.8 and 36.2% CP grains, herd mean) or two grains according to individual needs. Daily yields of milk, 4% FCM, SCM, and resulting intakes of grain were higher for cows fed two grains, but the increase in daily DMI and the decreases in daily forage intake and SCM:grain ratio were not significant. Fewer pluriparous cows (3 vs. 8 out of 19) on the two-grain treatment conceived after first service, but overall services per conception (1.97) were equal. Percentage of cows with SCC below linear score 4 (91%) was equal between treatments. Means adjusted by covariate 4% FCM resulted in more modest treatment effects. Advantage of two-grain versus one-grain treatment for milk per day was 7.7% for parity 1 and only 1.6% for parities greater than 1; corresponding responses (nonsignificant) for 4% FCM were 2.8 and 4.3, respectively. Forage DMI depressions on two-grain treatment were not significant. When covariate-adjusted means were used, the advantage in income over feed cost for individualized feeding of CP was $106 and $36/yr per cow in parities 1 and greater than 1 when cows produced 8209 kg (313 DIM) and 8527 kg (320 DIM) of milk, respectively.


Epiphytic microflora on alfalfa and whole-plant corn.

Epiphytic microflora were identified and counted on four cuttings of alfalfa, each harvested at three stages of maturity, and on three whole-plant corn hybrids. Enterobacteriaceae were predominant on both crops. Yeasts and molds also were major epiphytic microorganisms on whole-plant corn. The group--including lactobacilli, pediococci, and leuconostocs, which are genera that produce lactic acid and thus are instrumental in silage preservation--constituted only a small proportion of the total population (less than .5%) on both crops. Lactate-fermenting clostridial spores were not detected on standing alfalfa, and occurrences of these spores on standing corn plants were due to soil contamination from rainfall prior to harvest. The numbers of epiphytic microorganisms, except for the lactobacilli, pediococci, and leuconostocs group, were higher on standing corn than on alfalfa. The epiphytic microflora on alfalfa increased with increasing temperature during the growing season. However, neither cutting number nor maturity affected the epiphytic microflora on standing alfalfa, and wilting following mowing had little effect on most populations. Higher temperatures during wilting increased yeast and mold counts but had no effect on other microbial counts. The chopping process tended to increase the epiphytic microflora populations compared with those on the standing crops, and the group containing lactobacilli, pediococci, and leuconostocs was most enhanced. Only yeast and mold counts on the chopped alfalfa increased with greater DM content and buffering capacity.


In vitro effects of the thiopeptide A10255 on ruminal fermentation and microbial populations.

Experiments used unadapted mixed cultures of ruminal microorganisms in batch or continuous culture fermentation to investigate the effect of a thiopeptide, A10255, on ruminal fermentation and microbial populations. After 24 h of fermentation in batch culture, addition of A10255 (.5 to 20 ppm of the culture fluid) to 0, 45, 60, and 75% concentrate diets had no effect on total VFA but increased molar proportion of propionate and decreased butyrate. The molar proportion of acetate was decreased by treatment only in the 0 and 75% concentrate diets. The increase in molar proportion of propionate by 20 ppm of A10255 was less than the increase caused by a similar concentration of monensin. The same concentration of A10255 (20 ppm) decreased ADF digestion less than 20 ppm of monensin. In continuous culture, A10255 (33 mg/kg of dietary DM) did not affect total VFA concentration, culture pH, OM digestion, or ADF digestion. Ruminal bacterial populations of total anaerobes and lactate-producing, lactate-utilizing, cellulolytic and amylolytic bacteria were unaffected by treatment. However, molar proportions of acetate, butyrate, and isovalerate were decreased, and propionate was increased, by addition of A10255.


Effects of lasalocid and undegradable protein on growth and body composition of Holstein heifers.

Effects of lasalocid (0 or 200 mg/d per head) and undegradable intake protein (32 vs. 42% of CP in concentrate) on growth and body composition were evaluated using 32 Holstein heifers (253 kg initial BW, SE = 4). Heifers were housed in an open barn in eight pens of 4 heifers and fed 12.7 kg per pen daily of experimental concentrate with medium quality fescue hay for ad libitum consumption for 12 28-d periods. Body measurements were taken every 28 d; ultrasonic fat and muscle depths at the 13th rib, empty body fat, and protein were measured every 84 d. Heart girth and fat and muscle depth at the 13th rib increased when lasalocid and undegradable protein were fed individually, but not in combination. Rates of average daily gain and feed efficiency were not increased significantly when lasalocid and undegradable protein were fed. Data suggest that the combination of lasalocid and undegradable protein may have impaired microbial protein synthesis in the rumen, thereby influencing changes in body composition.


Effect of extra energy as fat or milk replacer solids in diets of young dairy calves on growth during cold weather.

The effects of feeding two levels of supplemental fat and extra milk replacer solids on Holstein calves housed in hutches during the winter were investigated. Fifty calves (10 per treatment) were assigned to the following dietary treatments: 1) milk replacer (control) reconstituted to 12.5% DM fed at 10% of BW (adjusted weekly), 2) same as treatment 1 plus 113 g/d of supplemental fat, 3) milk replacer reconstituted to 15% DM and fed at 10% of BW (adjusted weekly), 4) same as treatment 1 plus 226 g/d of supplemental fat, and 5) milk replacer reconstituted to 15% DM fed at 14% of BW (adjusted weekly). Half the amount of milk replacer consumed during wk 4 was fed during wk 5, and calves were weaned to dry feed at 35 d of age. A pelleted starter was offered for ad libitum intake throughout the 42-d trial. Gains in BW were greater for calves fed 226 than 113 or 0 g/d of supplemental fat (d 3 to 28). Calves fed milk replacer reconstituted to 15% DM at 14% of BW had greater BW gains during d 3 to 28 than control. Starter consumption was similar between groups receiving 113 and 0 g/d of fat supplement but lower in the group fed 226 g/d. Extra milk replacer solids in diets increased fecal scores to levels greater than those of calves in other groups. The benefit of fat supplementation of milk replacers was manifested as increased BW gain during the 1st mo of life.


Genetic and environmental relationships among somatic cell count, bacterial infection, and clinical mastitis.

Incidence of bacterial infection in 9784 lactations of 7763 cows in 31 herds, SCC in 32,448 lactations of 19,764 cows from 54 herds, and incidence of first parity mastitis recorded in the first lactations of 148,143 cows in 828 herds were analyzed. Bacterial infection was analyzed dichotomously by both threshold and linear models. The effects of parity, season, stage of lactation, and parity by stage of lactation interaction on SCC were estimated. Heritability of mean lactation log SCC--corrected for the effects of parity, season, and stage of lactation--varied from .13 to .27 for all parities in different data sets. Heritability of bacterial infection was .04 for the threshold model and .02 for the linear models. Heritability of field-recorded mastitis was .01. The genetic correlation between bacterial infection and SCC was near unity, but the genetic correlation between SCC and mastitis was .3. Selection for lowered SCC should reduce incidence of bacterial infection by 2% per unit of selection intensity.


Genetic analysis of fertility traits in Israeli Holsteins by linear and threshold models.

Conception rates of Israeli Holstein cows and heifers were analyzed separately by linear and threshold models. Fixed effects for both data files were insemination number, AI institute, geographical region, and calendar month. Analysis of cows also included the fixed effects of parity, calving status, and DIM at insemination. Random effects included in the models were herd-year-season, insemination technician, sire of cow, and service sire. Fixed effect solutions for heifers and cows were not similar. For cows, insemination month had the greatest effect on conception rate. Heritability of conception rate ranged from 2 to 3.5% for heifers and from 1 to 2% for cows. Correlations between corresponding threshold and linear model random effect solutions were all greater than or equal to .99. Correlations between heifer and cow analyses for sire and service sire solutions were less than .4. Analysis with an incorrect herd-year-season variance component affected only the technician solutions.


Associations between milk protein polymorphisms and milk production traits.

Associations between milk protein genotypes and milk production traits were estimated from 6803 first lactation records. Exact tests of associated hypotheses and unbiased estimates of genotype effects were from an animal model. Milk protein genotype effects were estimated using a model in which each milk protein gene was analyzed separately (single-gene analysis) and a model in which all milk protein genes were analyzed simultaneously (multigene analysis). The results of the two models indicate that some effects ascribed to certain milk protein genes in the single-gene analysis are not effects of the milk protein gene itself but of linked genes. Results from this study and from literature indicate that the kappa-casein gene or a very closely linked gene affects protein percentage, and the beta-lactoglobulin gene or a very closely linked gene affects fat percentage. Furthermore, effects of beta-casein genotypes on milk production, fat percentage, and protein yield were significant, and beta-lactoglobulin genotypes had significant effects on milk production and protein yield. It is less clear whether those effects are due to effects of milk protein genes themselves or to effects of linked genes.


Heat stress and milk production in the South Carolina coastal plains.

A model developed for the South Carolina coastal plains relates hours with temperature-humidity index values above 74 and 80 to summer season daily milk production. When tested on an independent production data set for 1985, the root mean square model error was less than 1.3 kg/d per cow. The model can be used to develop expected summer season dairy production climatologies. Real-time milk production forecasts obtained using daily predicted maximum and minimum temperatures can be used in herd management to reduce effects of heat stress on productivity.


External and internal markers for appraising site and extent of digestion in ruminants.

Digesta markers are used routinely to calculate fecal output and to estimate kinetics within the digestive tract. A marker suitable for estimating fecal output may not be a suitable kinetic marker because of problems with marker migration, phase separation, inhibition of digestion, osmotic effects within the gut, and quantitation. Marker validity should be checked when possible based on alternative methods (e.g., fecal output and ruminal evacuation). Certain parameters, such as pool size and passage rate, that can be estimated with markers cannot be measured by other noninvasive procedures. Nevertheless, only when marker results are verified by other methods can one evaluate the magnitude of error associated with assumptions inherent in marker mathematics (steady state, instantaneous mixing, and first-order kinetics). When marker results do not meet expectations, marker failure, rather than inadequate knowledge of gastrointestinal function or analytical difficulties, is blamed. No marker is ideal, but research to compare markers is useless if results are not related to direct flow or output measurements. Marker results often are adjusted for marker recovery based on the premise that analysis is precise and that losses are constant. Such adjustment is appropriate only if the error is analytical and proportional. Despite imprecision in marker procedures, inherent variation may be small relative to other sources of variation (e.g., gut physiology, diet, environment, and feed intake). Even though absolute values may be imprecise and inaccurate, marker-based estimates usually provide reliable information about the direction and extent of kinetic changes induced by treatments.


Markers for quantifying microbial protein synthesis in the rumen.

Measurement of ruminal microbial protein is necessary to quantify ruminal escape of dietary protein and microbial yields. Microbial markers used most widely have been the internal markers, diaminopimelic acid and nucleic acids (RNA, DNA, individual purines and pyrimidines, or total purines), and the external isotopic markers (e.g., 15N and 35S). Combined with digesta flow markers in ruminally and abomasally or intestinally cannulated ruminants, microbial yields can be estimated. An ideal marker system must account for both the bacterial and protozoal pools associated with both the fluid and particulate phases of digesta. No marker has proven completely satisfactory; hence, yield estimates are relative rather than absolute. Total purines represent robust microbial markers that should be adaptable by most investigators. Principal concerns about total purines relate to unequal purine: N ratios in protozoal and bacterial pools and to the need to assume that dietary purines are completely degraded in the rumen. A theoretically sounder, but more costly, method is continuous intraruminal infusion of 15N ammonium salts. However, 15N enrichments of bacterial and protozoal pools are not equal, so the basis for calculating microbial yield in faunated ruminants is uncertain. Urinary purine excretion may prove to be a noninvasive method for estimating microbial protein yields in intact dairy cows.


Initial biological testing of root canal sealing materials--a critical review.

A number of systems for the biological testing of dental materials have been suggested. This paper presents a critical review of the protocols suggested in the ISO standards for the initial and secondary biological testing of root canal sealing materials.


Prevalence and distribution of cervical dentine hypersensitivity in a population in Rio de Janeiro, Brazil.

The prevalence, distribution and possible causal factors of cervical dentine hypersensitivity were studied in a population from a Marine Dental Clinic in the city of Rio de Janeiro, Brazil. A total of 635 patients were examined for the presence of cervical dentine hypersensitivity by means of a questionnaire and intraoral tests (air and probe stimuli). There were 157 patients (25%) reporting to have hypersensitive teeth, but only 108 patients (17%) were diagnosed as having cervical dentine hypersensitivity. The prevalence of hypersensitivity was higher among females than males, but this difference was not statistically significant. Most females with hypersensitivity were aged 20-49 and most males were aged 40-59. Incisors and premolars had the highest prevalence of dentine hypersensitivity to air and probe stimuli, while molars had the lowest. The presence and history of dentine hypersensitivity were positively correlated with previous exposure to periodontal treatment. Only a few of the patients who claimed to have dentine hypersensitivity had tried treatment with desensitizing toothpastes or sought professional help.


Secondary retention of permanent molars: a report of five families.

The aetiopathogenesis of secondary retention is not fully understood, but heredity is involved in at least some cases. In this study first-degree relatives of 52 patients with secondary retention of permanent molars were screened for the presence of the same phenomenon in their dentition. Familial occurrence could be shown in five families. The pedigrees are compatible with autosomal dominant inheritance. HLA phenotypes and blood groups ABO, rhesus and P1 were studied in two families. The lod scores for linkage with secondary retention were added to previously reported information. The lod score for linkage for blood group system P increased from +0.940 to +1.475 at a recombination fraction of 5 per cent. It is concluded that secondary retention of permanent molars is an aetiologically heterogeneous condition in which some cases are caused by the presence of an abnormal autosomal dominant gene.


A critical comparison of dentifrice abrasion scores on dentine recorded by gravimetric and radiotracer methods.

Dentifrice abrasivity on dentine is conventionally ranked by various in vitro methods. The abrasivity of selected dentifrices in Switzerland was ranked in 1985 by the gravimetric and in 1989 by the radiotracer method. Because same-named brands of dentifrices were differently ranked by these methods, Swiss clinicians were unsure which ranking to follow. This paper lists the errors known to occur in both techniques, but unfortunately it is difficult to quantitate the magnitudes of these errors. Consequently, it is impossible to determine which method yields the more reliable results. Thus, researchers should look into the problem of dentifrice abrasion scores and try to formulate tests which could simplify the selection of brand-named dentifrices by clinicians and the consumers.


Cavity convergence angles for direct composite inlays.

Direct composite inlays may sometimes be difficult to remove from the cavity following primary polymerization. The aim of this work was to find the lowest cavity convergence angle (taper) which would allow reliable inlay removal. Cavity finish and cavity size were also taken into account. Standardized mesio-occlusal-distal cavities of 6 degrees taper were cut into 10 teeth of varying mesiodistal width and finished with either 12-bladed tungsten carbide or 25 microns diamond burs. After separating medium had been applied. Coltene Brilliant Dentin composite resin was packed into the cavity and light cured. The force required to remove the inlay was measured with an Instron Universal Testing Machine. The cavities were then refinished with the alternative finish and the experiment repeated. The same sequence was used for cavities of 12 degrees and finally 18 degrees convergence angle which were cut consecutively in the same 10 teeth. Force levels related to cavity convergence angle, cavity finish and tooth size were tested by ANOVA and regression analysis. The forces required to remove some of the inlays from the 6 degrees, and to a lesser extent 12 degrees angled cavities, proved unacceptably high, while an 18 degrees convergence angle resulted in statistically significant lower forces which were unlikely to damage tooth or inlay. Cavity finish and tooth size did not influence inlay withdrawal force.


Trigeminal somatosensory evoked potentials: a normal value study.

Normal somatosensory evoked potentials were obtained from the lower lip of 40 volunteers. Efforts were made to exclude artefact. A consistent triphasic wave form of three peaks and troughs was defined. There were greater variations in amplitude than latency between subjects. Statistically, one side of the lower lip can be used as a control for the contralateral side, but it may not be possible to have reliable normal values between subjects. Somatosensory evoked potentials may however represent an objective method of evaluating trigeminal sensory nerve function.