title: Zinc toxicity and its pathology in relation to facial eczema prophylaxis in ruminants

authors: Smith, Barry L.

abstract: Because of the possible administration of high dose rates of zinc compounds to ruminants as a prophylactic measure against facial eczema, the toxicities and pathological effects of certain zinc compounds have been examined in sheep and cattle.

At daily dose rates of zinc as low as 15 mg Zn/kg b.wt. lesions of zinc toxicity were observed but these were not always accompanied by clinical signs. After long term administration, zinc oxide treated sheep were heavier and fatter than controls. At higher dose rates of zinc oxide, body weight losses were recorded. Zinc sulphate caused greater weight loss, more deaths, more severe lesions and higher serum and organ zinc concentrations than zinc oxide which in turn was more toxic than zinc EDTA. Single zinc EDTA administrations resulted in more rapid rises and falls in serum zinc concentration and higher urinary zinc concentrations than the other two forms of zinc. Although most toxicity trials were conducted using sheep, some cattle were also dosed and these findings suggested that cattle react to high dose rates of zinc similarly to sheep.

The administration of zinc sulphate solutions to sheep and cattle by drenching gun caused abomasitis and other lesions of zinc toxicity were more severe and elevations of organ zinc higher than when the zinc was given by intraruminal intubation. Zinc solutions were shown to stimulate the reticular groove reflex causing the bolus to be deposited in the abomasum where it caused severe mucosal damage. When, for the same drenched dose rate of zinc sulphate, alternative combinations of volume and concentration were tried, it was shown that the greater volume alternative was more important than greater concentration in the production of zinc toxicity. 

Single intraruminal doses of zinc sulphate (100 and 200 mg Zn/kg b.wt) caused reductions in food intake, elevations of duodenal pH and the secretion of acid from isolated abomasal pouches was doubled. All forms of zinc administered caused lesions of the exocrine pancreas comprising duct necrosis and inflammation, acinar cell degeneration and inter-and intralobular fibrosis. The characteristics and chronology of these lesions suggested that the primary site of zinc-induced pancreopathy is in the pancreatic ductule. Severe pancreatic lesions caused by zinc oxide resulted in marked reductions of flow rates of pancreatic juice and in the concentration of protein and amylase in pancreatic juice. Although pancreatic bicarbonate output decreased, the concentration of bicarbonate in pancreatic juice was unaffected.

In subacute or chronic zinc sulphate toxicity of sheep and cattle there were often lesions indicative of one or more haemolytic episode. These consisted of a nephrosis and focal hepatic necrosis. Additional lesions seen in zinc toxicity were a periacinar fatty change, atrophy of ruminal papillae with epithelial metaplasia and a thymic atrophy. 

When zinc was added to the milk of sucking lambs (0 .2 g Zn ℓ) the typical pancreopathy of zinc toxicity occurred and, in addition, severe nephrosis with extremely high concentrations of kidney zinc were found. 

Zinc concentrations were increased considerably in liver, kidney and pancreas, but not muscle, in all experiments. After cessation of zinc dosing zinc concentrations in these organs rapidly returned to normal.

Zinc was shown to interfere with selenium metabolism but this did not appear to be responsible for any of the lesions recognised in zinc toxicity.

The addition of zinc sulphate to the sole drinking water (0.25, 0.5 and 1.0 g Zn/ℓ water) of yearling cattle for nine weeks reduced water consumption. This effect was greatest soon after the introduction of zinc to the drinking water. At the highest zinc concentration, there were pancreatic lesions in all cattle and less body weight gains than in controls.

text: Zinc toxicity and its pathology in relation to facial eczema prophylaxis in ruminants Because of the possible administration of high dose rates of zinc compounds to ruminants as a prophylactic measure against facial eczema, the toxicities and pathological effects of certain zinc compounds have been examined in sheep and cattle.

At daily dose rates of zinc as low as 15 mg Zn/kg b.wt. lesions of zinc toxicity were observed but these were not always accompanied by clinical signs. After long term administration, zinc oxide treated sheep were heavier and fatter than controls. At higher dose rates of zinc oxide, body weight losses were recorded. Zinc sulphate caused greater weight loss, more deaths, more severe lesions and higher serum and organ zinc concentrations than zinc oxide which in turn was more toxic than zinc EDTA. Single zinc EDTA administrations resulted in more rapid rises and falls in serum zinc concentration and higher urinary zinc concentrations than the other two forms of zinc. Although most toxicity trials were conducted using sheep, some cattle were also dosed and these findings suggested that cattle react to high dose rates of zinc similarly to sheep.

The administration of zinc sulphate solutions to sheep and cattle by drenching gun caused abomasitis and other lesions of zinc toxicity were more severe and elevations of organ zinc higher than when the zinc was given by intraruminal intubation. Zinc solutions were shown to stimulate the reticular groove reflex causing the bolus to be deposited in the abomasum where it caused severe mucosal damage. When, for the same drenched dose rate of zinc sulphate, alternative combinations of volume and concentration were tried, it was shown that the greater volume alternative was more important than greater concentration in the production of zinc toxicity. 

Single intraruminal doses of zinc sulphate (100 and 200 mg Zn/kg b.wt) caused reductions in food intake, elevations of duodenal pH and the secretion of acid from isolated abomasal pouches was doubled. All forms of zinc administered caused lesions of the exocrine pancreas comprising duct necrosis and inflammation, acinar cell degeneration and inter-and intralobular fibrosis. The characteristics and chronology of these lesions suggested that the primary site of zinc-induced pancreopathy is in the pancreatic ductule. Severe pancreatic lesions caused by zinc oxide resulted in marked reductions of flow rates of pancreatic juice and in the concentration of protein and amylase in pancreatic juice. Although pancreatic bicarbonate output decreased, the concentration of bicarbonate in pancreatic juice was unaffected.

In subacute or chronic zinc sulphate toxicity of sheep and cattle there were often lesions indicative of one or more haemolytic episode. These consisted of a nephrosis and focal hepatic necrosis. Additional lesions seen in zinc toxicity were a periacinar fatty change, atrophy of ruminal papillae with epithelial metaplasia and a thymic atrophy. 

When zinc was added to the milk of sucking lambs (0 .2 g Zn ℓ) the typical pancreopathy of zinc toxicity occurred and, in addition, severe nephrosis with extremely high concentrations of kidney zinc were found. 

Zinc concentrations were increased considerably in liver, kidney and pancreas, but not muscle, in all experiments. After cessation of zinc dosing zinc concentrations in these organs rapidly returned to normal.

Zinc was shown to interfere with selenium metabolism but this did not appear to be responsible for any of the lesions recognised in zinc toxicity.

The addition of zinc sulphate to the sole drinking water (0.25, 0.5 and 1.0 g Zn/ℓ water) of yearling cattle for nine weeks reduced water consumption. This effect was greatest soon after the introduction of zinc to the drinking water. At the highest zinc concentration, there were pancreatic lesions in all cattle and less body weight gains than in controls.

year: 1981

title: Biomechanics and subjective measures of recreational male runners in three shoes running outdoors: A randomised crossover study

authors: Hébert-Losier, Kim

subjects: comfort

abstract: We compared biomechanical and subjective data from outdoor running in: habitual (OWN), Saucony Endorphin Racer 2 minimal (FLAT) and Nike Vaporfly 4% (VP4) shoes. We also explored relationships between comfort measures and the collected data. Eighteen male recreational runners ran three 1.5-km trials outdoors, once per shoe. The first 1.1 km was run at a self-selected comfortable (slower) speed, and last 400 m at perceived 5-km race pace (faster). A GPS-enabled smartwatch, 15-m Optojump system, high-speed camera and tibial accelerometer collected biomechanical data. Subjective data on comfort, shoe properties and overall running experience were collected using visual analogue scales (VAS) and rankings. Cadence, leg stiffness and vertical stiffness were greater in FLAT than both OWN and VP4 at the slower speed (trivial to small ES). At both speeds, footstrike angles were smaller in FLAT (small to large ES), while propulsion phase was shorter in VP4 (moderate to large ES). FLAT was ranked as the least comfortable at the slower speed and most likely to cause injury, whereas OWN as the most comfortable and least likely to cause injury. Comfort was not significantly different at the faster speed between shoes. Comfort measures were more strongly correlated to subjective than biomechanical data. The two experimental shoes generally had non-significant or small effects on running biomechanics versus OWN. As VP4 are more like traditional than minimal shoes, these were perceived as more comfortable. Running speed appeared to affect subjective measures. Speed should be considered when prescribing and selecting shoes.

text: Biomechanics and subjective measures of recreational male runners in three shoes running outdoors: A randomised crossover study We compared biomechanical and subjective data from outdoor running in: habitual (OWN), Saucony Endorphin Racer 2 minimal (FLAT) and Nike Vaporfly 4% (VP4) shoes. We also explored relationships between comfort measures and the collected data. Eighteen male recreational runners ran three 1.5-km trials outdoors, once per shoe. The first 1.1 km was run at a self-selected comfortable (slower) speed, and last 400 m at perceived 5-km race pace (faster). A GPS-enabled smartwatch, 15-m Optojump system, high-speed camera and tibial accelerometer collected biomechanical data. Subjective data on comfort, shoe properties and overall running experience were collected using visual analogue scales (VAS) and rankings. Cadence, leg stiffness and vertical stiffness were greater in FLAT than both OWN and VP4 at the slower speed (trivial to small ES). At both speeds, footstrike angles were smaller in FLAT (small to large ES), while propulsion phase was shorter in VP4 (moderate to large ES). FLAT was ranked as the least comfortable at the slower speed and most likely to cause injury, whereas OWN as the most comfortable and least likely to cause injury. Comfort was not significantly different at the faster speed between shoes. Comfort measures were more strongly correlated to subjective than biomechanical data. The two experimental shoes generally had non-significant or small effects on running biomechanics versus OWN. As VP4 are more like traditional than minimal shoes, these were perceived as more comfortable. Running speed appeared to affect subjective measures. Speed should be considered when prescribing and selecting shoes.

year: 2023

title: Volunteering at the edge of chaos: A case study on the self-organising of younger volunteers during the Rena oil spill crisis

authors: Lockwood, Sarah Jane

subjects: volunteer

abstract: This thesis investigates the self-organising of younger volunteers during the 2011 Rena oil spill crisis in Aotearoa/New Zealand. It builds on emerging research that considers the relationships between volunteering and activism and focuses on the ways in which younger volunteers carved out a ‘volunteer-activist’ space for themselves on the edge of the formal crisis responses.  
The research adopts a case study approach and uses an interpretive lens to investigate three research questions: (1) How was volunteering conceptualised by younger volunteers involved in the Rena crisis?; (2) How did the generational dynamics of younger volunteers affect the various organising responses to the Rena event?; and, (3) How was self-organising conceptualised by younger volunteers involved in the Rena crisis?
The data comprised interviews with 53 participants, 38 of whom were classified as younger volunteers (16-29 years of age) and 15 who held positions of authority in the Rena crisis response and who had high levels of engagement with the younger volunteers. By examining the intersections and overlaps of self-organising, younger generations of volunteers, and crisis events through a social constructionist methodology combined with an interpretive lens and reflexive position, the thesis makes several theoretical and practical contributions.
At a theoretical level, the thesis challenges traditional crisis management approaches dominated by command and control, formal, or top down organisational structures and arrangements. The thesis demonstrates how, as active members of society, younger volunteers developed alternate forms of participation to strengthen crisis response. 
Power tensions between younger volunteers and crisis officials were grounded in a deep sense of frustration resulting from negative societal views toward younger generational cohorts and the structural workings of a risk society. By reconciling social and institutional grievances through self-organising, younger volunteers could take advantage of their marginalised position and enact self-reflexive responses in ways that were not readily available to them in everyday life. This sense of empowerment helped younger volunteers navigate the structural uncertainties they faced as they transitioned towards a competitive labour market and also to take greater control of their lives during a crisis.
From an Aotearoa/New Zealand, perspective, the thesis also provides insights into how younger Māori participants made sense of and enacted their ‘volunteer’ experience and how this experience was influenced by culturally embedded principles. Importantly, there appeared to be no generational differences between how younger and older Māori participants made sense of their ‘volunteer’ experience. Both groups were driven by collectivist orientations, which highlights the importance of contextualising culture in volunteer sector research. 
The social constructedness of the media technologies used by participants exposed broader power structures that existed within their generation-specific social worlds. To this end, media multiplexity showed how use of different communication technologies (1) supported the maintenance of relationships between participants and (2) was fundamental to the meaning participants attached to the different forms of technologies. These findings indicate the need to move away from the current literature’s focus on the tools of communication technologies used by younger people during crisis events, towards the meanings that exist behind the use of such technologies as well as the digital relationships fostered among volunteers. 
This thesis contributes to the scholarship on volunteering and activism by showing how self-organising emerged as an alternative form of activist—or activator—approach to volunteer participation within a crisis response. This approach enabled young volunteer-activators to move beyond their perceived sense of marginalisation and avoid those formal organisational forces that limit their sense of freedom and personal development. The result was an alternative crisis response of self-organised volunteering on the edge of chaos.

text: Volunteering at the edge of chaos: A case study on the self-organising of younger volunteers during the Rena oil spill crisis This thesis investigates the self-organising of younger volunteers during the 2011 Rena oil spill crisis in Aotearoa/New Zealand. It builds on emerging research that considers the relationships between volunteering and activism and focuses on the ways in which younger volunteers carved out a ‘volunteer-activist’ space for themselves on the edge of the formal crisis responses.  
The research adopts a case study approach and uses an interpretive lens to investigate three research questions: (1) How was volunteering conceptualised by younger volunteers involved in the Rena crisis?; (2) How did the generational dynamics of younger volunteers affect the various organising responses to the Rena event?; and, (3) How was self-organising conceptualised by younger volunteers involved in the Rena crisis?
The data comprised interviews with 53 participants, 38 of whom were classified as younger volunteers (16-29 years of age) and 15 who held positions of authority in the Rena crisis response and who had high levels of engagement with the younger volunteers. By examining the intersections and overlaps of self-organising, younger generations of volunteers, and crisis events through a social constructionist methodology combined with an interpretive lens and reflexive position, the thesis makes several theoretical and practical contributions.
At a theoretical level, the thesis challenges traditional crisis management approaches dominated by command and control, formal, or top down organisational structures and arrangements. The thesis demonstrates how, as active members of society, younger volunteers developed alternate forms of participation to strengthen crisis response. 
Power tensions between younger volunteers and crisis officials were grounded in a deep sense of frustration resulting from negative societal views toward younger generational cohorts and the structural workings of a risk society. By reconciling social and institutional grievances through self-organising, younger volunteers could take advantage of their marginalised position and enact self-reflexive responses in ways that were not readily available to them in everyday life. This sense of empowerment helped younger volunteers navigate the structural uncertainties they faced as they transitioned towards a competitive labour market and also to take greater control of their lives during a crisis.
From an Aotearoa/New Zealand, perspective, the thesis also provides insights into how younger Māori participants made sense of and enacted their ‘volunteer’ experience and how this experience was influenced by culturally embedded principles. Importantly, there appeared to be no generational differences between how younger and older Māori participants made sense of their ‘volunteer’ experience. Both groups were driven by collectivist orientations, which highlights the importance of contextualising culture in volunteer sector research. 
The social constructedness of the media technologies used by participants exposed broader power structures that existed within their generation-specific social worlds. To this end, media multiplexity showed how use of different communication technologies (1) supported the maintenance of relationships between participants and (2) was fundamental to the meaning participants attached to the different forms of technologies. These findings indicate the need to move away from the current literature’s focus on the tools of communication technologies used by younger people during crisis events, towards the meanings that exist behind the use of such technologies as well as the digital relationships fostered among volunteers. 
This thesis contributes to the scholarship on volunteering and activism by showing how self-organising emerged as an alternative form of activist—or activator—approach to volunteer participation within a crisis response. This approach enabled young volunteer-activators to move beyond their perceived sense of marginalisation and avoid those formal organisational forces that limit their sense of freedom and personal development. The result was an alternative crisis response of self-organised volunteering on the edge of chaos.

year: 2019